<s> [INST] <<SYS>> You are a responsible assistant committed to providing accurate and helpful responses. Avoid sharing harmful or biased content. Clarify any unclear or incorrect questions rather than providing false or misleading information. <</SYS>> What is 2 and can you explain it in depth? [/INST] 2 (two) is a number, numeral and digit. It is the natural number following 1 and preceding 3. It is the smallest and only even prime number. Because it forms the basis of a duality, it has religious and spiritual significance in many cultures.

Evolution
Arabic digit
The digit used in the modern Western world to represent the number 2 traces its roots back to the Indic Brahmic script, where "2" was written as two horizontal lines. The modern Chinese and Japanese languages (and Korean Hanja) still use this method. The Gupta script rotated the two lines 45 degrees, making them diagonal. The top line was sometimes also shortened and had its bottom end curve towards the center of the bottom line. In the Nagari script, the top line was written more like a curve connecting to the bottom line. In the Arabic Ghubar writing, the bottom line was completely vertical, and the digit looked like a dotless closing question mark. Restoring the bottom line to its original horizontal position, but keeping the top line as a curve that connects to the bottom line leads to our modern digit.In fonts with text figures, digit 2 usually is of x-height, for example, .

Etymology of two
The word two is derived from the Old English words twā (feminine), tū (neuter), and twēġen (masculine, which survives today in the form twain).The pronunciation /tuː/, like that of who is due to the labialization of the vowel by the w (combare from womb), which then disappeared before the related sound. The successive stages of pronunciation for the Old English twā would thus be /twɑː/, /twɔː/, /twoː/, /twuː/, and finally /tuː/.

In mathematics
Two is the smallest prime number, and the only even prime number, and for this reason it is sometimes called "the oddest prime". As the smallest prime number, it is also the smallest non-zero pronic number, and the only pronic prime. The next prime is three, which makes two and three the only two consecutive prime numbers. Two is the first prime number that does not have a proper twin prime with a difference two, while three is the first such prime number to have a twin prime. In consequence, the first pair of twin primes, three and five, encase four in-between, which is the square of two, or

          2

            2

    {\displaystyle 2^{2}}
  . Two is the first Sophie Germain prime, the first factorial prime, the first Lucas prime, and the first Ramanujan prime. It is also a Motzkin number,  a Bell number, an all-Harshad number, a meandric number, a semi-meandric number, an open meandric number, and the third (or fourth) Fibonacci number.An integer is called even if it is divisible by 2. For integers written in a numeral system based on an even number such as decimal, divisibility by 2 is easily tested by merely looking at the last digit. If it is even, then the whole number is even. In particular, when written in the decimal system, all multiples of 2 will end in 0, 2, 4, 6, or 8.Two is the base of the binary system, the numeral system with the fewest tokens that allows denoting a natural number n substantially more concisely (with log2 n  tokens) than a direct representation by the corresponding count of a single token (with n tokens). This binary number system is used extensively in computing.
For any number x:

x + x = 2 · x addition to multiplication
x · x = x2 multiplication to exponentiation
xx = x↑↑2 exponentiation to tetrationExtending this sequence of operations by introducing the notion of hyperoperations, here denoted by "hyper(a,b,c)" with a and c being the first and second operand, and b being the level in the above sketched sequence of operations, the following holds in general:

hyper(x,n,x) = hyper(x,(n + 1),2).Two has therefore the unique property that 2 + 2 = 2 · 2 = 22 = 2↑↑2 = 2↑↑↑2 = ..., disregarding the level of the hyperoperation, here denoted by Knuths up-arrow notation. The number of up-arrows refers to the level of the hyperoperation.
Two is the only number x such that the sum of the reciprocals of the natural powers of x equals itself. In symbols,

          ∑

            k
            =
            0

            ∞

            1

              2

                k

        =
        1
        +

            1
            2

        +

            1
            4

        +

            1
            8

        +

            1
            16

        +
        ⋯
        =
        2.

    {\displaystyle \sum _{k=0}^{\infty }{\frac {1}{2^{k}}}=1+{\frac {1}{2}}+{\frac {1}{4}}+{\frac {1}{8}}+{\frac {1}{16}}+\cdots =2.}
  This comes from the fact that:

          ∑

            k
            =
            0

            ∞

            1

              n

                k

        =
        1
        +

            1

              n
              −
              1

            for all

        n
        ∈

          R

        >
        1.

    {\displaystyle \sum _{k=0}^{\infty }{\frac {1}{n^{k}}}=1+{\frac {1}{n-1}}\quad {\mbox{for all}}\quad n\in \mathbb {R} >1.}
  A Cantor space is a topological space

          2

              N

    {\displaystyle 2^{\mathbb {N} }}
   homeomorphic to the Cantor set. The countably infinite product topology of the simplest discrete two-point space, {0, 1}, is the traditional elementary example.
The sum of the reciprocals of all non-zero triangular numbers converges to

        2

    {\displaystyle 2}
  .Powers of two are central to the concept of Mersenne primes, and important to computer science. Two is the first Mersenne prime exponent.
Taking the square root of a number is such a common mathematical operation, that the spot on the root sign where the index would normally be written for cubic and other roots, may simply be left blank for square roots, as it is tacitly understood.
The square root of 2 was the first known irrational number.
The smallest field has two elements.
In a set-theoretical construction of the natural numbers, 2 is identified with the set {{∅},∅}. This latter set is important in category theory: it is a subobject classifier in the category of sets.
Two consecutive twos (as in "22" for "two twos"), or equivalently "2-2", is the only fixed point of John Conways look-and-say function </s>


<s> [INST] <<SYS>> You are a responsible assistant committed to providing accurate and helpful responses. Avoid sharing harmful or biased content. Clarify any unclear or incorrect questions rather than providing false or misleading information. <</SYS>> What is Dislocation of jaw and can you explain it in depth? [/INST] Dislocations occur when two bones that originally met at the joint detach. Dislocations should not be confused with Subluxation. Subluxation is when the joint is still partially attached to the bone.When a person has a dislocated jaw it is difficult to open and close the mouth. Dislocation can occur following a series of events if the jaw locks while open or unable to close. If the jaw is dislocated, it may cause an extreme headache or inability to concentrate. When the muscles alignment is out of sync, a pain will occur due to unwanted rotation of the jaw.If the pain remains constant, it may require surgery to realign the jaw. Depending on the severity of the jaws dislocation, pain relief such as paracetamol may assist to alleviate the initial chronic pain. If the pain relief is taken for an extended period of time, it may negatively affect the person while talking, eating, drinking, etc.

Symptoms
The symptoms can be numerous depending on the severity of the dislocation injury and how long the person is inflicted with the injury. Symptoms of a dislocated jaw include a bite that feels “off” or abnormal, hard time talking or moving jaw, not able to close mouth completely, drooling due to not being able to shut mouth completely, teeth feel they are out of alignment, and a pain that becomes unbearableThe immediate symptom can be a loud crunch noise occurring right up against the eardrum.  This is instantly followed by excruciating pain, particularly in the side where the dislocation occurred.Short-term symptoms can range from mild to chronic headaches, muscle tension or pain in the face, jaw and neck.Long-term symptoms can result in sleep deprivation, tiredness/lethargy, frustration, bursts of anger or short fuse, difficulty performing everyday tasks, depression, social issues relating to difficulty talking, hearing sensitivity (particularly to high pitched sounds), tinnitus and pain when seated associated with posture while at a computer and reading books from general pressure on the jaw and facial muscles when tilting head down or up. And possible causing subsequent facial asymmetry.In contrast, symptoms of a fractured jaw include bleeding coming from the mouth, unable to open the mouth wide without pain, bruising and swelling of the face, difficulty eating due to the constant pain, loss of feeling in the face (more specifically the lower lip) and lacks full range of motion of the jaw.

Anatomy
The joint involved with jaw dislocation is the temporomandibular joint (TMJ). This joint is located where the mandibular condyles and the temporal bone meet. Membranes that surround the bones help during the hinging and gliding of jaw movement. For the mouth to close it requires the following muscles: the masseter, temporalis, and medial pterygoid muscle. For the jaw to open it requires the lateral pterygoid muscle.

Pathophysiology
There are four different positions of jaw dislocation: posterior, anterior, superior and lateral. The most common position is anterior, while the other types are rare. Anterior dislocation shifts the lower jaw forward if the mouth excessively opens. This type of dislocation may happen bilaterally or unilaterally after yawning. The muscles that are affected during anterior jaw dislocation are the masseter and temporalis which pull up on the mandible and the lateral pterygoid which relaxes the mandibular condyle. The condyle can get locked in front of the articular eminence. Posterior dislocation is possible for people who get injured by being punched in the chin. This dislocation will push the jaw back affecting the alignment of the mandibular condyle and mastoid. The external auditory canal may be fractured. Superior dislocations occur after being punched below the mandibular ramus as the mouth remains half-open. Since great force occurs in a punch, the angle of the jaw will be forced upward moving towards the condylar head. This can result in a fracture of the glenoid fossa and displacement of the condyle into the middle cranial fossa, potentially injuring the facial and vestibulocochlear nerves and the temporal lobe. Lateral dislocations move the mandibular condyle away from the skull and are likely to happen together with jaw fractures.Posterior, superior and lateral dislocations are uncommon injuries and usually result from high-energy trauma to the chin. By contrast, anterior dislocations are more often the result of low-energy trauma (e.g. tooth extraction) or secondary to a medical condition that affects the stability of the joint (e.g. seizures, ligamentous laxity, degeneration of joint capsule).

Diagnosis
As with other joint dislocations, clinical history and examination are crucial for diagnosis of a jaw dislocation. Commonly, plain and panoramic X-ray radiographies are used to determine the relative position of the mandibular condyle. If a complex or unusual injury is suspected, three-dimensional computed tomography is most reliable in diagnosing dislocation and possibly associated fractures or soft tissue injuries.In case of dislocations resulting from high-energy trauma, attention must also be paid to possible other injuries, particularly blunt or indirect trauma to the skull and cervical spine. Acutely life-threatening conditions need to be ruled out or treated in first line. For superior jaw dislocation in particular, serious intracranial complications such as epidural hematoma are possible and must be recognized and managed to prevent disability or even death. Therefore, neurological status has to be examined in patients with complex dislocations involving temporal bone fractures. Hearing deficits on the injured side may indicate damage to structures of the ear.

Treatment
Most temporomandibular disorders (TMDs) are self-limiting and do not get worse. Simple treatment, involving self-care practices, rehabilitation aimed at eliminating muscle spasms, and restoring correct coordination, is all that is required. Nonsteroidal anti-inflammatory analgesics (NSAIDs) should be used on a short-term, regular basis and not on an as needed basis </s>


<s> [INST] <<SYS>> You are a responsible assistant committed to providing accurate and helpful responses. Avoid sharing harmful or biased content. Clarify any unclear or incorrect questions rather than providing false or misleading information. <</SYS>> What is Viral disease and can you explain it in depth? [/INST] A viral disease (or viral infection) occurs when an organisms body is invaded by pathogenic viruses, and infectious virus particles (virions) attach to and enter susceptible cells.

Structural Characteristics
Basic structural characteristics, such as genome type, virion shape and replication site, generally share the same features among virus species within the same family.
Double-stranded DNA families: three are non-enveloped (Adenoviridae, Papillomaviridae and Polyomaviridae) and two are enveloped (Herpesviridae and Poxviridae). All of the non-enveloped families have icosahedral capsids.
Partly double-stranded DNA viruses: Hepadnaviridae. These viruses are enveloped.
One family of single-stranded DNA viruses infects humans: Parvoviridae </s>


<s> [INST] <<SYS>> You are a responsible assistant committed to providing accurate and helpful responses. Avoid sharing harmful or biased content. Clarify any unclear or incorrect questions rather than providing false or misleading information. <</SYS>> What is Alcoholic cardiomyopathy and can you explain it in depth? [/INST] Alcoholic cardiomyopathy is a disease in which the chronic long-term abuse of alcohol (i.e., ethanol) leads to heart failure </s>


<s> [INST] <<SYS>> You are a responsible assistant committed to providing accurate and helpful responses. Avoid sharing harmful or biased content. Clarify any unclear or incorrect questions rather than providing false or misleading information. <</SYS>> What is Cardiac tamponade and can you explain it in depth? [/INST] Cardiac tamponade, also known as pericardial tamponade (), is the buildup of fluid in the pericardium (the sac around the heart), resulting in compression of the heart. Onset may be rapid or gradual. Symptoms typically include those of obstructive shock including shortness of breath, weakness, lightheadedness, and cough. Other symptoms may relate to the underlying cause.Common causes of cardiac tamponade include cancer, kidney failure, chest trauma, myocardial infarction, and pericarditis. Other causes include connective tissues diseases, hypothyroidism, aortic rupture, autoimmune disease, and complications of cardiac surgery. In Africa, tuberculosis is a relatively common cause.Diagnosis may be suspected based on low blood pressure, jugular venous distension, or quiet heart sounds (together known as Becks triad). A pericardial rub may be present in cases due to inflammation. The diagnosis may be further supported by specific electrocardiogram (ECG) changes, chest X-ray, or an ultrasound of the heart. If fluid increases slowly the pericardial sac can expand to contain more than 2 liters; however, if the increase is rapid, as little as 200 mL can result in tamponade.Tamponade is a medical emergency. When it results in symptoms, drainage is necessary. This can be done by pericardiocentesis, surgery to create a pericardial window, or a pericardiectomy. Drainage may also be necessary to rule out infection or cancer. Other treatments may include the use of dobutamine or in those with low blood volume, intravenous fluids. Those with few symptoms and no worrisome features can often be closely followed. The frequency of tamponade is unclear. One estimate from the United States places it at 2 per 10,000 per year.

Signs and symptoms
Onset may be rapid (acute) or more gradual (subacute). Signs of cardiac tamponade typically include those of cardiogenic shock including shortness of breath, weakness, lightheadedness, cough and those of Becks triad e.g. jugular vein distention, quiet heart sounds and hypotension. Other symptoms may relate to the underlying cause.Other general signs of shock (such as fast heart rate, shortness of breath and decreasing level of consciousness) may also occur. However, some of these signs may not be present in certain cases. A fast heart rate, although expected, may be absent in people with uremia and hypothyroidism.According to Reddy, cardiac tamponade and its progression can be described in 3 different phases. In phase I, the required filling pressure increases due to the high stiffness of the ventricles. This is because of the accumulation of pericardial fluid in the pericardial cavity. During phase II, the pericardial pressure exceeds the ventricular filling pressure caused by the further accumulation of pericardial fluid. This results in a decrease in cardiac input and output. A further decrease of cardiac input and output is typical in phase III of the progression of cardiac tamponade. This is caused by the equilibration of left ventricular filling and pericardial pressure, leading to “severe deterioration of end-organ perfusion.” Some of the symptoms, as a consequence, include abdominal pain due to liver engorgement.

Causes
Cardiac tamponade is caused by a large or uncontrolled pericardial effusion, i.e. the buildup of fluid inside the pericardium. This commonly occurs as a result of chest trauma (both blunt and penetrating), but can also be caused by myocardial infarction, myocardial rupture, cancer (most often Hodgkin lymphoma), uremia, pericarditis, or cardiac surgery, and rarely occurs during retrograde aortic dissection, or while the person is taking anticoagulant therapy. The effusion can occur rapidly (as in the case of trauma or myocardial rupture), or over a more gradual period of time (as in cancer). The fluid involved is often blood, but pus is also found in some circumstances.

Surgery
One of the most common settings for cardiac tamponade is in the first 7 days after heart surgery.  After heart surgery, chest tubes are placed to drain blood.  These chest tubes, however, are prone to clot formation.  When a chest tube becomes occluded or clogged, the blood that should be drained can accumulate around the heart, leading to tamponade.

Pathophysiology
The pericardium, the double-walled sac surrounding the heart, consists of a fibrous pericardium layer on the outside and a double-layered serous pericardium on the inside. Between the two layers of the serous pericardium is the pericardial space, which is filled with lubricating serous fluid that prevents friction as the heart contracts. The outer layer of the heart is made of fibrous tissue which does not easily stretch, so once excess fluid begins to enter the pericardial space, pressure starts to increase. Consequently, the heart becomes compressed due to its inability to fully relax.If fluid continues to accumulate, each successive diastolic period leads to less blood entering the ventricles. Eventually, increasing pressure on the heart forces the septum to bend in towards the left ventricle, leading to a decrease in stroke volume. This causes the development of obstructive shock, which if left untreated may lead to cardiac arrest (often presenting as pulseless electrical activity). The decrease in stroke volume can also ultimately lead to a decrease in cardiac output, which could be signaled by tachycardia and hypotension.

Diagnosis
The three classic signs, known as Becks triad, are low blood pressure, jugular-venous distension, and muffled heart sounds. Other signs may include pulsus paradoxus (a drop of at least 10 mmHg in arterial blood pressure with inspiration), and ST segment changes on the electrocardiogram, which may also show low voltage QRS complexes.

Medical imaging
Tamponade can often be diagnosed radiographically. Echocardiography, which is the diagnostic test of choice, often demonstrates an enlarged pericardium or collapsed ventricles. A large cardiac tamponade will show as an enlarged globular-shaped heart on chest x-ray. During inspiration, the negative pressure in the thoracic cavity will cause increased pressure into the right ventricle.  This increased pressure in the right ventricle will cause the interventricular septum to bulge towards the left ventricle, leading to decreased filling of the left ventricle. At the same time, right ventricle volume is markedly diminished and sometimes it can collapse.

Differential diagnosis
Initial diagnosis of cardiac tamponade can be challenging, as there is a broad differential diagnosis. The differential includes possible diagnoses based on symptoms, time course, mechanism of injury, patient history. Rapid onset cardiac tamponade may also appear similar to pleural effusions, shock, pulmonary embolism, and tension pneumothorax.If symptoms appeared more gradually, the differential diagnosis includes acute heart failure.In a person with trauma presenting with pulseless electrical activity in the absence of hypovolemia and tension pneumothorax, the most likely diagnosis is cardiac tamponade.In addition to the diagnostic complications afforded by the wide-ranging differential diagnosis for chest pain, diagnosis can be additionally complicated by the fact that people will often be weak or faint at presentation. For instance, a fast rate of breathing and difficulty breathing on exertion that progresses to air hunger at rest can be a key diagnostic symptom, but it may not be possible to obtain such information from people who are unconscious or who have convulsions at presentation.

Treatment
Pre-hospital care
Initial treatment given will usually be supportive in nature, for example administration of oxygen, and monitoring. There is little care that can be provided pre-hospital other than general treatment for shock. Some teams have performed an emergency thoracotomy to release clotting in the pericardium caused by a penetrating chest injury.Prompt diagnosis and treatment is the key to survival with tamponade.  Some pre-hospital providers will have facilities to provide pericardiocentesis, which can be life-saving.  If the person has already suffered a cardiac arrest, pericardiocentesis alone cannot ensure survival, and so rapid evacuation to a hospital is usually the more appropriate course of action.

Hospital management
Initial management in hospital is by pericardiocentesis </s>


<s> [INST] <<SYS>> You are a responsible assistant committed to providing accurate and helpful responses. Avoid sharing harmful or biased content. Clarify any unclear or incorrect questions rather than providing false or misleading information. <</SYS>> What is Lactose intolerance and can you explain it in depth? [/INST] Lactose intolerance is a common condition caused by a decreased ability to digest lactose, a sugar found in dairy products. Those affected vary in the amount of lactose they can tolerate before symptoms develop. Symptoms may include abdominal pain, bloating, diarrhea, flatulence, and nausea. These symptoms typically start thirty minutes to two hours after eating or drinking milk-based food. Their severity typically depends on the amount a person eats or drinks. Lactose intolerance does not cause damage to the gastrointestinal tract.Lactose intolerance is due to the lack of the enzyme lactase in the small intestines to break lactose down into glucose and galactose. There are four types: primary, secondary, developmental, and congenital. Primary lactose intolerance occurs as the amount of lactase declines as people age. Secondary lactose intolerance is due to injury to the small intestine. Such injury could be the result of infection, celiac disease, inflammatory bowel disease, or other diseases. Developmental lactose intolerance may occur in premature babies and usually improves over a short period of time. Congenital lactose intolerance is an extremely rare genetic disorder in which little or no lactase is made from birth. The onset of primary lactose intolerance, the most common type, is typically in late childhood or early adulthood, but prevalence increases with age.Diagnosis may be confirmed if symptoms resolve following eliminating lactose from the diet. Other supporting tests include a hydrogen breath test and a stool acidity test. Other conditions that may produce similar symptoms include irritable bowel syndrome, celiac disease, and inflammatory bowel disease. Lactose intolerance is different from a milk allergy. Management is typically by decreasing the amount of lactose in the diet, taking lactase supplements, or treating the underlying disease. People are able to drink at least one cup of milk without developing symptoms, with greater amounts tolerated if drunk with a meal or throughout the day.Worldwide, around 65% of adults are affected by lactose malabsorption. Other mammals usually lose the ability to digest lactose after weaning and this was the ancestral state of all humans before the recent evolution of lactase persistence, which extends lactose tolerance into adulthood. Lactase persistence evolved in several populations independently, probably as an adaptation to the domestication of dairy animals around 10,000 years ago. Today the prevalence of lactose tolerance varies widely between regions and ethnic groups. The ability to digest lactose is most common in people of European descent, and to a lesser extent in parts of the Middle East and Africa. Traditional food cultures reflect local variations in tolerance and historically many societies have adapted to low levels of tolerance by making dairy products that contain less lactose than fresh milk. The medicalization of lactose intolerance as a disorder has been attributed to biases in research history, since most early studies were conducted amongst populations which are normally tolerant, as well as the cultural and economic importance of milk in countries such as the United States.

Terminology
Lactose intolerance primarily refers to a syndrome with one or more symptoms upon the consumption of food substances containing lactose sugar. Individuals may be lactose intolerant to varying degrees, depending on the severity of these symptoms.
Hypolactasia is the term specifically for the small intestine producing little or no lactase enzyme.  If a person with hypolactasia consumes lactose sugar, it results in lactose malabsorption.  The digestive system is unable to process the lactose sugar, and the unprocessed sugars in the gut produce the symptoms of lactose intolerance.
Lactose intolerance is not an allergy, because it is not an immune response, but rather a sensitivity to dairy caused by a deficiency of lactase enzyme. Milk allergy, occurring in about 2% of the population, is a separate condition, with distinct symptoms that occur when the presence of milk proteins trigger an immune reaction.

Signs and symptoms
The principal manifestation of lactose intolerance is an adverse reaction to products containing lactose (primarily milk), including abdominal bloating and cramps, flatulence, diarrhea, nausea, borborygmi, and vomiting (particularly in adolescents). These appear one-half to two hours after consumption. The severity of these signs and symptoms typically increases with the amount of lactose consumed; most lactose-intolerant people can tolerate a certain level of lactose in their diets without ill effects.Because lactose intolerance is not an allergy, it does not produce allergy symptoms (such as itching, hives, or anaphylaxis).

Causes
Lactose intolerance is a consequence of lactase deficiency, which may be genetic (primary hypolactasia and primary congenital alactasia) or environmentally induced (secondary or acquired hypolactasia). In either case, symptoms are caused by insufficient levels of lactase in the lining of the duodenum. Lactose, a disaccharide molecule found in milk and dairy products, cannot be directly absorbed through the wall of the small intestine into the bloodstream, so, in the absence of lactase, passes intact into the colon. Bacteria in the colon can metabolise lactose, and the resulting fermentation produces copious amounts of gas (a mixture of hydrogen, carbon dioxide, and methane) that causes the various abdominal symptoms. The unabsorbed sugars and fermentation products also raise the osmotic pressure of the colon, causing an increased flow of water into the bowels (diarrhea).Lactose intolerance in infants (congenital lactase deficiency) is caused by mutations in the LCT gene. The LCT gene provides the instructions for making lactase. Mutations are believed to interfere with the function of lactase, causing affected infants to have a severely impaired ability to digest lactose in breast milk or formula. Lactose intolerance in adulthood is a result of gradually decreasing activity (expression) of the LCT gene after infancy, which occurs in most humans. The specific DNA sequence in the MCM6 gene helps control whether the LCT gene is turned on or off. At least several thousand years ago, some humans developed a mutation in the MCM6 gene that keeps the LCT gene turned on even after breast feeding is stopped. Populations that are lactose intolerant lack this mutation.  The LCT and MCM6 genes are both located on the long arm (q) of chromosome 2 in region 21. The locus can be expressed as 2q21. The lactase deficiency also could be linked to certain heritages and varies widely. A 2016 study of over 60,000 participants from 89 countries found regional prevalence of lactose malabsorption was "64% (54–74) in Asia (except Middle East), 47% (33–61) in eastern Europe, Russia, and former Soviet Republics, 38% (CI 18–57) in Latin America, 70% (57–83) in the Middle East, 66% (45–88) in northern Africa, 42% (13–71) in northern America, 45% (19–71) in Oceania, 63% (54–72) in sub-Saharan Africa, and 28% (19–37) in northern, southern and western Europe." According to Johns Hopkins Medicine, lactose intolerance is more common in Asian Americans, African Americans, Mexican Americans, and Native Americans. Analysis of the DNA of 94 ancient skeletons in Europe and Russia concluded that the mutation for lactose tolerance appeared about 4,300 years ago and spread throughout the European population.Some human populations have developed lactase persistence, in which lactase production continues into adulthood probably as a response to the benefits of being able to digest milk from farm animals. Some have argued that this links intolerance to natural selection favoring lactase-persistent individuals, but it is also consistent with a physiological response to decrease lactase production when it is not needed in cultures in which dairy products are not an available food source. Although populations in Europe, India, Arabia, and Africa were first thought to have high rates of lactase persistence because of a single mutation, lactase persistence has been traced to a number of mutations that occurred independently. Different alleles for lactase persistence have developed at least three times in East African populations, with persistence extending from 26% in Tanzania to 88% in the Beja pastoralist population in Sudan.The accumulation of epigenetic factors, primarily DNA methylation, in the extended LCT region, including the gene enhancer located in the MCM6 gene near C/T-13910 SNP, may also contribute to the onset of lactose intolerance in adults. Age-dependent expression of LCT in mice intestinal epithelium has been DNA methylation in the gene enhancer.Lactose intolerance is classified according to its causes as:

Primary hypolactasia
Primary hypolactasia, or primary lactase deficiency, is genetic, only affects adults, and is caused by the absence of a lactase persistence allele. In individuals without the lactase persistence allele, less lactase is produced by the body over time, leading to hypolactasia in adulthood. The frequency of lactase persistence, which allows lactose tolerance, varies enormously worldwide, with the highest prevalence in Northwestern Europe, declines across southern Europe and the Middle East and is low in Asia and most of Africa, although it is common in pastoralist populations from Africa.

Secondary hypolactasia
Secondary hypolactasia or secondary lactase deficiency, also called acquired hypolactasia or acquired lactase deficiency, is caused by an injury to the small intestine. This form of lactose intolerance can occur in both infants and lactase persistent adults and is generally reversible. It may be caused by acute gastroenteritis, coeliac disease, Crohns disease, ulcerative colitis, chemotherapy, intestinal parasites (such as giardia), or other environmental causes.

Primary congenital alactasia
Primary congenital alactasia, also called congenital lactase deficiency, is an extremely rare, autosomal recessive enzyme defect that prevents lactase expression from birth. People with congenital lactase deficiency cannot digest lactose from birth, so cannot digest breast milk. This genetic defect is characterized by a complete lack of lactase (alactasia). About 40 cases have been reported worldwide, mainly limited to Finland. Before the 20th century, babies born with congenital lactase deficiency often did not survive, but death rates decreased with soybean-derived infant formulas and manufactured lactose-free dairy products.

Diagnosis
In order to assess lactose intolerance, intestinal function is challenged by ingesting more dairy products than can be readily digested.  Clinical symptoms typically appear within 30 minutes, but may take up to two hours, depending on other foods and activities.  Substantial variability in response (symptoms of nausea, cramping, bloating, diarrhea, and flatulence) is to be expected, as the extent and severity of lactose intolerance varies among individuals.The next step is to determine whether it is due to primary lactase deficiency or an underlying disease that causes secondary lactase deficiency. Physicians should investigate the presence of undiagnosed coeliac disease, Crohn disease, or other enteropathies when secondary lactase deficiency is suspected and infectious gastroenteritis has been ruled out.Lactose intolerance is distinct from milk allergy, an immune response to cows milk proteins. They may be distinguished in diagnosis by giving lactose-free milk, producing no symptoms in the case of lactose intolerance, but the same reaction as to normal milk in the presence of a milk allergy. A person can have both conditions. If positive confirmation is necessary, four tests are available.

Hydrogen breath test
In a hydrogen breath test, the most accurate lactose intolerance test, after an overnight fast, 25 grams of lactose (in a solution with water) are swallowed. If the lactose cannot be digested, enteric bacteria metabolize it and produce hydrogen, which, along with methane, if produced, can be detected on the patients breath by a clinical gas chromatograph or compact solid-state detector. The test takes about 2.5 hours to complete. If the hydrogen levels in the patients breath are high, they may have lactose intolerance. This test is not usually done on babies and very young children, because it can cause severe diarrhea.

Lactose tolerance test
In conjunction, measuring blood glucose level every 10 to 15 minutes after ingestion will show a "flat curve" in individuals with lactose malabsorption, while the lactase persistent will have a significant "top", with a typical elevation of 50% to 100%, within one to two hours. However, due to the need for frequent blood sampling, this approach has been largely replaced by breath testing.After an overnight fast, blood is drawn and then 50 grams of lactose (in aqueous solution) are swallowed. Blood is then drawn again at the 30-minute, 1-hour, 2-hour, and 3-hour marks.  If the lactose cannot be digested, blood glucose levels will rise by less than 20 mg/dl.

Stool acidity test
This test can be used to diagnose lactose intolerance in infants, for whom other forms of testing are risky or impractical. The infant is given lactose to drink. If the individual is tolerant, the lactose is digested and absorbed in the small intestine; otherwise, it is not digested and absorbed, and it reaches the colon. The bacteria in the colon, mixed with the lactose, cause acidity in stools. Stools passed after the ingestion of the lactose are tested for level of acidity. If the stools are acidic, the infant is intolerant to lactose.
Stool pH in lactose intolerance is less than 5.5.

Intestinal biopsy
An intestinal biopsy must confirm lactase deficiency following discovery of elevated hydrogen in the hydrogen breath test.  Modern techniques have enabled a bedside test, identifying presence of lactase enzyme on upper gastrointestinal endoscopy instruments.  However, for research applications such as mRNA measurements, a specialist laboratory is required.

Stool sugar chromatography
Chromatography can be used to separate and identify undigested sugars present in faeces. Although lactose may be detected in the faeces of people with lactose intolerance, this test is not considered reliable enough to conclusively diagnose or exclude lactose intolerance.

Genetic diagnostic
Genetic tests may be useful in assessing whether a person has primary lactose intolerance. Lactase activity persistence in adults is associated with two polymorphisms: C/T 13910 and G/A 22018 located in the MCM6 gene. These polymorphisms may be detected by molecular biology techniques at the DNA extracted from blood or saliva samples; genetic kits specific for this diagnosis are available. The procedure consists of extracting and amplifying DNA from the sample, following with a hybridation protocol in a strip. Colored bands are obtained as result, and depending on the different combinations, it would be possible to determine whether the patient is lactose intolerant. This test allows a noninvasive definitive diagnostic.

Frequency
Lactose intolerance is most common in people of East Asian descent, with 70 to 100 percent of people affected in these communities. Lactose intolerance is also more common in people of West African, Arab, and Jewish descent, while only about 5 percent of people of European descent are lactose intolerant.

Management
When lactose intolerance is due to secondary lactase deficiency, treatment of the underlying disease may allow lactase activity to return to normal levels. In people with celiac disease, lactose intolerance normally reverts or improves several months after starting a gluten-free diet, but temporary dietary restriction of lactose may be needed.People with primary lactase deficiency cannot modify their bodys ability to produce lactase. In societies where lactose intolerance is the norm, it is not considered a condition that requires treatment. However, where dairy is a larger component of the normal diet, a number of efforts may be useful. There are four general principles in dealing with lactose intolerance: avoidance of dietary lactose, substitution to maintain nutrient intake, regulation of calcium intake, and use of enzyme substitute. Regular consumption of dairy food by lactase deficient individuals may also reduce symptoms of intolerance by promoting colonic bacteria adaptation.

Dietary avoidance
The primary way of managing the symptoms of lactose intolerance is to limit the intake of lactose to a level that can be tolerated. Lactase deficient individuals vary in the amount of lactose they can tolerate, and some report that their tolerance varies over time, depending on health status and pregnancy. However, as a rule of thumb, people with primary lactase deficiency and no small intestine injury are usually able to consume at least 12 grams of lactose per sitting without symptoms, or with only mild symptoms, with greater amounts tolerated if consumed with a meal or throughout the day.
Lactose is found primarily in dairy products, which vary in the amount of lactose they contain:

Milk – unprocessed cows milk is about 4.7% lactose; goats milk 4.7%; sheeps milk 4.7%; buffalo milk 4.86%; and yak milk 4.93%.
Sour cream and buttermilk – if made in the traditional way, this may be tolerable, but most modern brands add milk solids.
Butter – the process of making butter largely removes lactose, but it is still present in small quantities; clarified butter contains a negligible amount of lactose.
Yogurt – lactobacilli used in the production of yogurt metabolize lactose to varying degrees, depending on the type of yogurt. Some bacteria found in yogurt also produce their own lactase, which facilitates digestion in the intestines of lactose intolerant individuals.
Cheese – fermentation also reduces the lactose content of cheeses and aging reduces it further; traditionally made hard cheeses might contain just 10% of the lactose found in an equivalent volume of milk. However, manufactured cheeses may be produced using processes that do not have the same lactose-reducing properties.There is no standardized method for measuring the lactose content of food. The stated dairy content of a product also varies according to manufacturing processes and labelling practices, and commercial terminology varies between languages and regions. As a result, absolute figures for the amount of lactose consumed (by weight) may not be very reliable. Kosher products labeled pareve or fleishig are free of milk. However, if a "D" (for "dairy") is present next to the circled "K", "U", or other hechsher, the food product likely contains milk solids, although it may also simply indicate the product was produced on equipment shared with other products containing milk derivatives.
Lactose is also a commercial food additive used for its texture, flavor, and adhesive qualities. It is found in additives labelled as casein, caseinate, whey, lactoserum, milk solids, modified milk ingredients, etc. As such lactose is found in foods such as processed meats (sausages/hot dogs, sliced meats, pâtés), gravy stock powder, margarines, sliced breads, breakfast cereals, potato chips, processed foods, medications, prepared meals, meal replacements (powders and bars), protein supplements (powders and bars), and even beers in the milk stout style. Some barbecue sauces and liquid cheeses used in fast-food restaurants may also contain lactose. Lactose is often used as the primary filler (main ingredient) in most prescription and non-prescription solid pill form medications, though product labeling seldom mentions the presence of lactose or milk, and neither do product monograms provided to pharmacists, and most pharmacists are unaware of the very wide scale yet common use of lactose in such medications until they contact the supplier or manufacturer for verification.

Milk substitutes
Plant-based milks and derivatives such as soy milk, rice milk, almond milk, coconut milk, hazelnut milk, oat milk, hemp milk, macadamia nut milk, and peanut milk are inherently lactose-free.  Low-lactose and lactose-free versions of foods are often available to replace dairy-based foods for those with lactose intolerance.

Lactase supplements
When lactose avoidance is not possible, or on occasions when a person chooses to consume such items, then enzymatic lactase supplements may be used.Lactase enzymes similar to those produced in the small intestines of humans are produced industrially by fungi of the genus Aspergillus. The enzyme, β-galactosidase, is available in tablet form in a variety of doses, in many countries without a prescription. It functions well only in high-acid environments, such as that found in the human gut due to the addition of gastric juices from the stomach. Unfortunately, too much acid can denature it, so it should not be taken on an empty stomach. Also, the enzyme is ineffective if it does not reach the small intestine by the time the problematic food does. Lactose-sensitive individuals can experiment with both timing and dosage to fit their particular needs.
While essentially the same process as normal intestinal lactose digestion, direct treatment of milk employs a different variety of industrially produced lactase. This enzyme, produced by yeast from the genus Kluyveromyces, takes much longer to act, must be thoroughly mixed throughout the product, and is destroyed by even mildly acidic environments. Its main use is in producing the lactose-free or lactose-reduced dairy products sold in supermarkets.

Rehabituation to dairy products
Regular consumption of dairy foods containing lactose can promote a colonic bacteria adaptation, enhancing a favorable microbiome, which allows people with primary lactase deficiency to diminish their intolerance and to consume more dairy foods. The way to induce tolerance is based on progressive exposure, consuming smaller amounts frequently, distributed throughout the day. Lactose intolerance can also be managed by ingesting live yogurt cultures containing lactobacilli that are able to digest the lactose in other dairy products.

Epidemiology
Worldwide, about 65% of people experience some form of lactose intolerance as they age past infancy, but there are significant differences between populations and regions. As few as 5% of northern Europeans are lactose intolerant, while as many as 90% of adults in parts of Asia are lactose intolerant.Some populations, from an evolutionary perspective, have a better genetic makeup for tolerating lactose than others. In northern European countries, early adoption of dairy farming conferred a selective evolutionary advantage to individuals that could better tolerate lactose. This led to higher frequencies of lactose tolerance in these countries. For example, almost 100% of Irish people are predicted to be lactose tolerant. Conversely, regions of the south, such as Africa, did not adopt dairy farming as early and tolerance from milk consumption did not develop the same way as in northern Europe. Lactose intolerance is common among people of Jewish descent, as well as from West Africa, the Arab countries, Greece, and Italy. Different populations will present certain gene constructs depending on the evolutionary and cultural pre-settings of the geographical region.

History
Greater lactose tolerance has come about in two ways. Some populations have developed genetic changes to allow the digestion of lactose: lactase persistence. Other populations developed cooking methods like milk fermentation.Lactase persistence in humans evolved relatively recently (in the last 10,000 years) among some populations. Around 8,000 years ago in modern-day Turkey, humans became reliant on newly-domesticated animals that could be milked; such as cows, sheep, and goats. This resulted in higher frequency of lactase persistence. Lactase persistence became high in regions such as Europe, Scandinavia, the Middle East and Northwestern India. However, most people worldwide remain lactase non-persistent. Populations that raised animals not used for milk tend to have 90–100 percent of a lactose intolerant rate.  For this reason, lactase persistence is of some interest to the fields of anthropology, human genetics, and archaeology, which typically use the genetically derived persistence/non-persistence terminology.The rise of dairy and producing dairy related products from cow milk alone, varies across different regions of the world, aside from genetic predisposition. The process of turning milk into cheese dates back earlier than 5200 BC.DNA analysis in February 2012 revealed that Ötzi was lactose intolerant, supporting the theory that lactose intolerance was still common at that time, despite the increasing spread of agriculture and dairying.Genetic analysis shows lactase persistence has developed several times in different places independently in an example of convergent evolution.

History of research
It is not until relatively recently that medicine recognised the worldwide prevalence of lactose intolerance and its genetic causes. Its symptoms were described as early as Hippocrates (460–370 BC), but until the 1960s, the prevailing assumption was that tolerance was the norm. Intolerance was explained as the result of a milk allergy, intestinal pathogens, or as being psychosomatic – it being recognised that some cultures did not practice dairying, and people from those cultures often reacted badly to consuming milk. Two reasons have been given for this misconception </s>


<s> [INST] <<SYS>> You are a responsible assistant committed to providing accurate and helpful responses. Avoid sharing harmful or biased content. Clarify any unclear or incorrect questions rather than providing false or misleading information. <</SYS>> What is Tobacco smoking and can you explain it in depth? [/INST] Tobacco smoking is the practice of burning tobacco and ingesting the resulting smoke. The smoke may be inhaled, as is done with cigarettes, or simply released from the mouth, as is generally done with pipes and cigars. The practice is believed to have begun as early as 5000–3000 BC in Mesoamerica and South America. Tobacco was introduced to Eurasia in the late 17th century by European colonists, where it followed common trade routes. The practice encountered criticism from its first import into the Western world onwards but embedded itself in certain strata of a number of societies before becoming widespread upon the introduction of automated cigarette-rolling apparatus.Smoking is the most common method of consuming tobacco, and tobacco is the most common substance smoked. The agricultural product is often mixed with additives and then combusted. The resulting smoke is then inhaled and the active substances absorbed through the alveoli in the lungs or the oral mucosa. Many substances in cigarette smoke trigger chemical reactions in nerve endings, which heighten heart rate, alertness and reaction time, among other things. Dopamine and endorphins are released, which are often associated with pleasure.German scientists identified a link between smoking and lung cancer in the late 1920s, leading to the first anti-smoking campaign in modern history, albeit one truncated by the collapse of Nazi Germany at the end of World War II. In 1950, British researchers demonstrated a clear relationship between smoking and cancer. Evidence continued to mount in the 1960s, which prompted political action against the practice. Rates of consumption since 1965 in the developed world have either peaked or declined. However, they continue to climb in the developing world. As of 2008 to 2010, tobacco is used by about 49% of men and 11% of women aged 15 or older in fourteen low-income and middle-income countries (Bangladesh, Brazil, China, Egypt, India, Mexico, Philippines, Russia, Thailand, Turkey, Ukraine, Uruguay and Vietnam), with about 80% of this usage in the form of smoking. The gender gap tends to be less pronounced in lower age groups.Many smokers begin during adolescence or early adulthood. During the early stages, a combination of perceived pleasure acting as positive reinforcement and desire to respond to social peer pressure may offset the unpleasant symptoms of initial use, which typically include nausea and coughing. After an individual has smoked for some years, the avoidance of withdrawal symptoms and negative reinforcement become the key motivations to continue.
A 2009 study of first smoking experiences of seventh-grade students found out that the most common factor leading students to smoke is cigarette advertisements. Smoking by parents, siblings and friends also encourages students to smoke.

History
Use in ancient cultures
Smokings history dates back to as early as 5000–3000 BC, when the agricultural product began to be cultivated in Mesoamerica and South America; consumption later evolved into burning the plant substance either by accident or with intent of exploring other means of consumption. The practice worked its way into shamanistic rituals. Many ancient civilizations – such as the Babylonians, the Indians, and the Chinese – burnt incense during religious rituals. Smoking in the Americas probably had its origins in the incense-burning ceremonies of shamans but was later adopted for pleasure or as a social tool. The smoking of tobacco and various hallucinogenic drugs was used to achieve trances and to come into contact with the spirit world. Also, to stimulate respiration, tobacco smoke enemas were used.Eastern North American tribes would carry large amounts of tobacco in pouches as a readily accepted trade item and would often smoke it in ceremonial pipes, either in sacred ceremonies or to seal bargains. Adults as well as children enjoyed the practice. It was believed that tobacco was a gift from the Creator and that the exhaled tobacco smoke was capable of carrying ones thoughts and prayers to heaven.Apart from smoking, tobacco had uses as medicine. As a pain killer it was used for earache and toothache and occasionally as a poultice. Smoking was said by the desert Indians to be a cure for colds, especially if the tobacco was mixed with the leaves of the small Desert sage, Salvia dorrii, or the root of Indian balsam or cough root, Leptotaenia multifida, the addition of which was thought to be particularly good for asthma and tuberculosis.

Popularization
In 1612, six years after the settlement of Jamestown, Virginia, John Rolfe was credited as the first settler to successfully raise tobacco as a cash crop. The demand quickly grew as tobacco, referred to as "brown gold", revived the Virginia joint stock company from its failed gold expeditions. In order to meet demands from the Old World, tobacco was grown in succession, quickly depleting the soil. This became a motivator to settle west into the unknown continent, and likewise an expansion of tobacco production. Indentured servitude became the primary labor force up until Bacons Rebellion, from which the focus turned to slavery. This trend abated following the American Revolution as slavery became regarded as unprofitable. However, the practice was revived in 1794 with the invention of the cotton gin.Frenchman Jean Nicot (from whose name the word nicotine is derived) introduced tobacco to France in 1560, and tobacco then spread to England. The first report of a smoking Englishman is of a sailor in Bristol in 1556, seen "emitting smoke from his nostrils". Like tea, coffee and opium, tobacco was just one of many intoxicants that was originally used as a form of medicine. Tobacco was introduced around 1600 by French merchants in what today is modern-day Gambia and Senegal. At the same time, caravans from Morocco brought tobacco to the areas around Timbuktu, and the Portuguese brought the commodity (and the plant) to southern Africa, establishing the popularity of tobacco throughout all of Africa by the 1650s.
Soon after its introduction to the Old World, tobacco came under frequent criticism from state and religious leaders. James VI and I, King of Scotland and England, produced the treatise A Counterblaste to Tobacco in 1604, and also introduced excise duty on the product. Murad IV, sultan of the Ottoman Empire 1623–40 was among the first to attempt a smoking ban by claiming it was a threat to public morals and health. The Chongzhen Emperor of China issued an edict banning smoking two years before his death and the overthrow of the Ming dynasty. Later, the Manchu rulers of the Qing dynasty, would proclaim smoking "a more heinous crime than that even of neglecting archery". In Edo period Japan, some of the earliest tobacco plantations were scorned by the shogunate as being a threat to the military economy by letting valuable farmland go to waste for the use of a recreational drug instead of being used to plant food crops.

Religious leaders have often been prominent among those who considered smoking immoral or outright blasphemous. In 1634, the Patriarch of Moscow forbade the sale of tobacco, and sentenced men and women who flouted the ban to have their nostrils slit and their backs flayed. Pope Urban VIII likewise condemned smoking on holy places in a papal bull of 1624. Despite some concerted efforts, restrictions and bans were largely ignored. When James I of England, a staunch anti-smoker and the author of A Counterblaste to Tobacco, tried to curb the new trend by enforcing a 4000% tax increase on tobacco in 1604 it was unsuccessful, as suggested by the presence of around 7,000 tobacco outlets in London by the early 17th century. From this point on for some centuries, several administrations withdrew from efforts at discouragement and instead turned tobacco trade and cultivation into sometimes lucrative government monopolies.By the mid-17th century most major civilizations had been introduced to tobacco smoking and in many cases had already assimilated it into the native culture, despite some continued attempts upon the parts of rulers to eliminate the practice with penalties or fines. Tobacco, both product and plant, followed the major trade routes to major ports and markets, and then on into the hinterlands. The English language term smoking appears to have entered currency in the late 18th century, before which less abbreviated descriptions of the practice such as drinking smoke were also in use.Growth in the US remained stable until the American Civil War in 1860s, when the primary agricultural workforce shifted from slavery to sharecropping. This, along with a change in demand, accompanied the industrialization of cigarette production as craftsman James Bonsack created a machine in 1881 to partially automate their manufacture.

Social attitudes and public health
In Germany, anti-smoking groups, often associated with anti-liquor groups, first published advocacy against the consumption of tobacco in the journal Der Tabakgegner (The Tobacco Opponent) in 1912 and 1932. In 1929, Fritz Lickint of Dresden, Germany, published a paper containing formal statistical evidence of a lung cancer–tobacco link. During the Great Depression Adolf Hitler condemned his earlier smoking habit as a waste of money, and later with stronger assertions. This movement was further strengthened with Nazi reproductive policy as women who smoked were viewed as unsuitable to be wives and mothers in a German family. In the 20th century, smoking was common. There were social events like the smoke night which promoted the habit.
The anti-tobacco movement in Nazi Germany did not reach across enemy lines during the Second World War, as anti-smoking groups quickly lost popular support. By the end of the Second World War, American cigarette manufacturers quickly reentered the German black market. Illegal smuggling of tobacco became prevalent, and leaders of the Nazi anti-smoking campaign were silenced. As part of the Marshall Plan, the United States shipped free tobacco to Germany; with 24,000 tons in 1948 and 69,000 tons in 1949. Per capita yearly cigarette consumption in post-war Germany steadily rose from 460 in 1950 to 1,523 in 1963. By the end of the 20th century, anti-smoking campaigns in Germany were unable to exceed the effectiveness of the Nazi-era climax in the years 1939–41 and German tobacco health research was described by Robert N. Proctor as "muted".

In 1950, Richard Doll published research in the British Medical Journal showing a close link between smoking and lung cancer. Beginning in December 1952, the magazine Readers Digest published "Cancer by the Carton", a series of articles that linked smoking with lung cancer.In 1954, the British Doctors Study, a prospective study of some 40 thousand doctors for about 2.5 years, confirmed the suggestion, based on which the government issued advice that smoking and lung cancer rates were related. In January 1964, the United States Surgeon Generals Report on Smoking and Health likewise began suggesting the relationship between smoking and cancer.As scientific evidence mounted in the 1980s, tobacco companies claimed contributory negligence as the adverse health effects were previously unknown or lacked substantial credibility. Health authorities sided with these claims up until 1998, from which they reversed their position. The Tobacco Master Settlement Agreement, originally between the four largest US tobacco companies and the Attorneys General of 46 states, restricted certain types of tobacco advertisement and required payments for health compensation; which later amounted to the largest civil settlement in United States history.Social campaigns have been instituted in many places to discourage smoking, such as Canadas National Non-Smoking Week.
From 1965 to 2006, rates of smoking in the United States declined from 42% to 20.8%. The majority of those who quit were professional, affluent men. Although the per-capita number of smokers decreased, the average number of cigarettes consumed per person per day increased from 22 in 1954 to 30 in 1978. This paradoxical event suggests that those who quit smoked less, while those who continued to smoke moved to smoke more light cigarettes. The trend has been paralleled by many industrialized nations as rates have either leveled-off or declined. In the developing world, however, tobacco consumption continues to rise at 3.4% in 2002. In Africa, smoking is in most areas considered to be modern, and many of the strong adverse opinions that prevail in the West receive much less attention. Today Russia leads as the top consumer of tobacco followed by Indonesia, Laos, Ukraine, Belarus, Greece, Jordan, and China.As a result of public pressure and the FDA, Walmart and Sams club announced that they were raising the minimum age to purchase tobacco products, including all e-cigarettes, to 21 starting  1 July 2019.

Consumption
Methods
Tobacco is an agricultural product processed from the fresh leaves of plants in the genus Nicotiana. The genus contains several species, of which Nicotiana tabacum is the most commonly grown. Nicotiana rustica follows second, containing higher concentrations of nicotine. The leaves are harvested and cured to allow the slow oxidation and degradation of carotenoids in tobacco leaf. This produces certain compounds in the tobacco leaves which can be attributed to sweet hay, tea, rose oil, or fruity aromatic flavors. Before packaging, the tobacco is often combined with other additives in order to increase the addictive potency, shift the products pH, or improve the effects of smoke by making it more palatable. In the United States these additives are regulated to 599 substances. The product is then processed, packaged, and shipped to consumer markets.

Beedi
Beedis are thin South Asian cigarettes filled with tobacco flakes and wrapped in a tendu leaf tied with a string at one end. They produce higher levels of carbon monoxide, nicotine, and tar than cigarettes typical in the United States.
Cigars
Cigars are tightly rolled bundles of dried and fermented tobacco which are ignited so that smoke may be drawn into the smokers mouth. They are generally not inhaled because of the high alkalinity of the smoke, which can quickly become irritating to the trachea and lungs. The prevalence of cigar smoking varies depending on location, historical period, and population surveyed, and prevalence estimates vary somewhat depending on the survey method. The United States is the top consuming country by far, followed by Germany and the United Kingdom; the US and Western Europe account for about 75% of cigar sales worldwide. As of 2005 it is estimated that 4.3% of men and 0.3% of women smoke cigars in the USA.Cigarettes
Cigarettes, French for "small cigar", are a product consumed through smoking and manufactured out of cured and finely cut tobacco leaves and reconstituted tobacco, often combined with other additives, which are then rolled or stuffed into a paper-wrapped cylinder. Cigarettes are ignited and inhaled, usually through a cellulose acetate filter, into the mouth and lungs.

Hookah
Hookah are a single or multi-stemmed (often glass-based) water pipe for smoking. Originally from India. The hookah was a symbol of pride and honor for the landlords, kings and other such high class people.  Now, the hookah has gained immense popularity, especially in the Middle East. A hookah operates by water filtration and indirect heat. It can be used for smoking herbal fruits, tobacco, or cannabis.
Kretek
Kretek are cigarettes made with a complex blend of tobacco, cloves and a flavoring "sauce". It was first introduced in the 1880s in Kudus, Java, to deliver the medicinal eugenol of cloves to the lungs. The quality and variety of tobacco play an important role in kretek production, from which kretek can contain more than 30 types of tobacco. Minced dried clove buds weighing about one-third of the tobacco blend are added to add flavoring. In 2004 the United States prohibited cigarettes from having a "characterizing flavor" of certain ingredients other than tobacco and menthol, thereby removing kretek from being classified as cigarettes.
Pipe smoking
Pipe smoking is done with a tobacco pipe, typically consisting of a small chamber (the bowl) for the combustion of the tobacco to be smoked and a thin stem (shank) that ends in a mouthpiece (the bit). Shredded pieces of tobacco are placed into the chamber and ignited.
Roll-your-own
Roll-your-own or hand-rolled cigarettes, often called "rollies", "cigi" or "Roll-ups", are very popular particularly in European countries and the UK. These are prepared from loose tobacco, cigarette papers, and filters all bought separately. They are usually much cheaper than ready-made cigarettes and small contraptions can be bought making the process easier.
Vaporizer
A vaporizer is a device used to sublimate the active ingredients of plant material. Rather than burning the herb, which produces potentially irritating, toxic, or carcinogenic by-products; a vaporizer heats the material in a partial vacuum so that the active compounds contained in the plant boil off into a vapor. This method is often preferable when medically administrating the smoke substance, as opposed to directly pyrolyzing the plant material.

Physiology
The active substances in tobacco, especially cigarettes, are administered by burning the leaves and inhaling the vaporized gas that results. This quickly and effectively delivers substances into the bloodstream by absorption through the alveoli in the lungs. The lungs contain some 300 million alveoli, which amounts to a surface area of over 70 m2 (about the size of a tennis court). This method is not completely efficient as not all of the smoke will be inhaled, and some amount of the active substances will be lost in the process of combustion, pyrolysis. Pipe and Cigar smoke are not inhaled because of its high alkalinity, which are irritating to the trachea and lungs. However, because of its higher alkalinity (pH 8.5) compared to cigarette smoke (pH 5.3), non-ionized nicotine is more readily absorbed through the mucous membranes in the mouth. Nicotine absorption from cigar and pipe, however, is much less than that from cigarette smoke. Nicotine and cocaine activate similar patterns of neurons, which supports the existence of common substrates among these drugs.The absorbed nicotine mimics nicotinic acetylcholine which when bound to nicotinic acetylcholine receptors prevents the reuptake of acetylcholine thereby increasing that neurotransmitter in those areas of the body. These nicotinic acetylcholine receptors are located in the central nervous system and at the nerve-muscle junction of skeletal muscles; whose activity increases heart rate, alertness, and faster reaction times. Nicotine acetylcholine stimulation is not directly addictive. However, since dopamine-releasing neurons are abundant on nicotine receptors, dopamine is released; and, in the nucleus accumbens, dopamine is associated with motivation causing reinforcing behavior. Dopamine increase, in the prefrontal cortex, may also increase working memory.When tobacco is smoked, most of the nicotine is pyrolyzed. However, a dose sufficient to cause mild somatic dependency and mild to strong psychological dependency remains. There is also a formation of harmane (an MAO inhibitor) from the acetaldehyde in tobacco smoke. This may play a role in nicotine addiction, by facilitating a dopamine release in the nucleus accumbens as a response to nicotine stimuli. Using rat studies, withdrawal after repeated exposure to nicotine results in less responsive nucleus accumbens cells, which produce dopamine responsible for reinforcement.

Demographics
As of 2000, smoking was practiced by around 1.22 billion people. At current rates of smoker replacement and market growth, this may reach around 1.9 billion in 2025.Smoking may be up to five times more prevalent among men than women in some communities, although the gender gap usually declines with younger age. In some developed countries smoking rates for men have peaked and begun to decline, while for women they continue to climb.As of 2002, about twenty percent of young teenagers (13–15) smoked worldwide. 80,000 to 100,000 children begin smoking every day, roughly half of whom live in Asia. Half of those who begin smoking in adolescent years are projected to go on to smoke for 15 to 20 years. As of 2019 in the United States, roughly 800,000 high school students smoke.The World Health Organization (WHO) states that "Much of the disease burden and premature mortality attributable to tobacco use disproportionately affect the poor". Of the 1.22 billion smokers, 1 billion of them live in developing or transitional economies. Rates of smoking have leveled off or declined in the developed world. In the developing world, however, tobacco consumption is rising by 3.4% per year as of 2002.The WHO in 2004 projected 58.8 million deaths to occur globally, from which 5.4 million are tobacco-attributed, and 4.9 million as of 2007. As of 2002, 70% of the deaths are in developing countries. As of 2017, smoking causes one in ten deaths worldwide, with half of those deaths in the US, China, India and Russia.

Psychology
Takeup
Most smokers begin smoking during adolescence or early adulthood. Some studies also show that smoking can also be linked to various mental health complications. Smoking has elements of risk-taking and rebellion, which often appeal to young people. The presence of peers that smoke and media featuring high-status models smoking may also encourage smoking. Because teenagers are influenced more by their peers than by adults, attempts by parents, schools, and health professionals at preventing people from trying cigarettes are often unsuccessful.Children of smoking parents are more likely to smoke than children with non-smoking parents. Children of parents who smoke are less likely to quit smoking. One study found that parental smoking cessation was associated with less adolescent smoking, except when the other parent currently smoked. A current study tested the relation of adolescent smoking to rules regulating where adults are allowed to smoke in the home. Results showed that restrictive home smoking policies were associated with lower likelihood of trying smoking for both middle and high school students.Behavioural research generally indicates that teenagers begin their smoking habits due to peer pressure, and cultural influence portrayed by friends. However, one study found that direct pressure to smoke cigarettes played a less significant part in adolescent smoking, with adolescents also reporting low levels of both normative and direct pressure to smoke cigarettes. Mere exposure to tobacco retailers may motivate smoking behaviour in adults. A similar study suggested that individuals may play a more active role in starting to smoke than has previously been thought and that social processes other than peer pressure also need to be taken into account. Another studys results indicated that peer pressure was significantly associated with smoking behavior across all age and gender cohorts, but that intrapersonal factors were significantly more important to the smoking behavior of 12- to 13-year-old girls than same-age boys. Within the 14- to 15-year-old age group, one peer pressure variable emerged as a significantly more important predictor of girls than boys smoking. It is debated whether peer pressure or self-selection is a greater cause of adolescent smoking.
Psychologist Hans Eysenck (who later was questioned for nonplausible results
 and unsafe publications) developed a personality profile for the typical smoker. Extraversion is the trait that is most associated with smoking, and smokers tend to be sociable, impulsive, risk taking, and excitement seeking individuals.

Persistence
The reasons given by some smokers for this activity have been categorized as addictive smoking, pleasure from smoking, tension reduction/relaxation, social smoking, stimulation, habit/automatism, and handling. There are gender differences in how much each of these reasons contribute, with females more likely than males to cite tension reduction/relaxation, stimulation and social smoking.Some smokers argue that the depressant effect of smoking allows them to calm their nerves, often allowing for increased concentration. However, according to the Imperial College London, "Nicotine seems to provide both a stimulant and a depressant effect, and it is likely that the effect it has at any time is determined by the mood of the user, the environment and the circumstances of use. Studies have suggested that low doses have a depressant effect, while higher doses have stimulant effect."

Patterns
A number of studies have established that cigarette sales and smoking follow distinct time-related patterns. For example, cigarette sales in the United States of America have been shown to follow a strongly seasonal pattern, with the high months being the months of summer, and the low months being the winter months.Similarly, smoking has been shown to follow distinct circadian patterns during the waking day—with the high point usually occurring shortly after waking in the morning, and shortly before going to sleep at night.

Impact
Health
Tobacco smoking is the leading cause of preventable death and a global public health concern. There are 1.1 billion tobacco users in the world. One person dies every six seconds from a tobacco related disease.

Tobacco use leads most commonly to diseases affecting the heart and lungs, with smoking being a major risk factor for heart attacks, strokes, chronic obstructive pulmonary disease (COPD), idiopathic pulmonary fibrosis (IPF), emphysema, and various types and subtypes of cancers (particularly lung cancer, cancers of the oropharynx, larynx, and mouth, esophageal and pancreatic cancer). Cigarette smoking increases the risk of Crohns disease as well as the severity of the course of the disease. It is also the number one cause of bladder cancer. Cigarette smoking has also been associated with sarcopenia, the age-related loss of muscle mass and strength. The smoke from tobacco elicits carcinogenic effects on the tissues of the body that are exposed to the smoke. Regular cigar smoking is known to carry serious health risks, including increased risk of developing various types and subtypes of cancers, respiratory diseases, cardiovascular diseases, cerebrovascular diseases, periodontal diseases and teeth loss, and malignant diseases.Tobacco smoke is a complex mixture of over 7,000 toxic chemicals, 98 of which are associated with an increased risk of cardiovascular disease and 69 of which are known to be carcinogenic. The most important chemicals causing cancer are those that produce DNA damage, since such damage appears to be the primary underlying cause of cancer. Cunningham et al. combined the microgram weight of the compound in the smoke of one cigarette with the known genotoxic effect per microgram to identify the most carcinogenic compounds in cigarette smoke: acrolein, formaldehyde, acrylonitrile, 1,3-butadiene, acetaldehyde, ethylene oxide, and isoprene. In addition to the aforementioned toxic chemicals, flavored tobacco contains flavorings which upon heating release toxic chemicals and carcinogens such as carbon monoxide (CO), polycyclic aromatic hydrocarbons (PAHs), furans, phenols, aldehydes (such as acrolein), and acids, in addition to nitrogenous carcinogens, alcohols, and heavy metals, all of which are dangerous to human health. A comparison of 13 common hookah flavors found that melon flavors are the most dangerous, with their smoke containing four classes of hazards in high concentrations.The World Health Organization estimates that tobacco caused 5.4 million deaths in 2004 and 100 million deaths over the course of the 20th century. Similarly, the United States Centers for Disease Control and Prevention describes tobacco use as "the single most important preventable risk to human health in developed countries and an important cause of premature death worldwide." Although 70% of smokers state their intention to quit only 3–5% are actually successful in doing so.The probabilities of death from lung cancer before age 75 in the United Kingdom are 0.2% for men who never smoked (0.4% for women), 5.5% for male former smokers (2.6% in women), 15.9% for current male smokers (9.5% for women) and 24.4% for male "heavy smokers" defined as smoking more than 5 cigarettes per day (18.5% for women). Tobacco smoke can combine with other carcinogens present within the environment in order to produce elevated degrees of lung cancer.
The risk of lung cancer decreases almost from the first day someone quits smoking. Healthy cells that have escaped mutations grow and replace the damaged ones in the lungs. In the research dated December 2019, 40% of cells in former smokers looked like those of people who had never smoked.Rates of smoking have generally leveled-off or declined in the developed world. Smoking rates in the United States have dropped by half from 1965 to 2006, falling from 42% to 20.8% in adults. In the developing world, tobacco consumption is rising by 3.4% per year.Smoking alters the transcriptome of the lung parenchyma; the expression levels of a panel of seven genes (KMO, CD1A, SPINK5, TREM2, CYBB, DNASE2B, FGG) are increased in the lung tissue of smokers.Passive smoking is the inhalation of tobacco smoke by individuals who are not actively smoking. This smoke is known as second-hand smoke (SHS) or environmental tobacco smoke (ETS) when the burning end is present, and third-hand smoke after the burning end has been extinguished. Because of its negative implications, exposure to SHS has played a central role in the regulation of tobacco products. Six hundred thousand deaths were attributed to SHS in 2004. It also has been known to produce skin conditions such as freckles and dryness.In 2015, a meta-analysis found that smokers were at greater risk of developing psychotic disorder. Tobacco has also been described an anaphrodisiac due to its propensity for causing erectile dysfunction. There is a correlation between tobacco smoking and a reduced risk of Parkinsons disease.

Economic
In countries where there is a universally funded healthcare system, the government covers the cost of medical care for smokers who become ill through smoking in the form of increased taxes. Two broad debating positions exist on this front, the "pro-smoking" argument suggesting that heavy smokers generally do not live long enough to develop the costly and chronic illnesses which affect the elderly, reducing societys healthcare burden, and the "anti-smoking" argument suggests that the healthcare burden is increased because smokers get chronic illnesses younger and at a higher rate than the general population.  Data on both positions has been contested. The Centers for Disease Control and Prevention published research in 2002 claiming that the cost of each pack of cigarettes sold in the United States was more than $7 in medical care and lost productivity. The cost may be higher, with another study putting it as high as $41 per pack, most of which however is on the individual and his/her family. This is how one author of that study puts it when he explains the very low cost for others: "The reason the number is low is that for private pensions, Social Security, and Medicare — the biggest factors in calculating costs to society — smoking actually saves money. Smokers die at a younger age and dont draw on the funds theyve paid into those systems." Other research demonstrates that premature death caused by smoking may redistribute Social Security income in unexpected ways that affect behavior and reduce the economic well-being of smokers and their dependents. To further support this, whatever the rate of smoking consumption is per day, smokers have a greater lifetime medical cost on average compared to a non-smoker by an estimated $6000 Between the cost for lost productivity and health care expenditures combined, cigarette smoking costs at least 193 billion dollars (Research also shows that smokers earn less money than nonsmokers). As for secondhand smoke, the cost is over 10 billion dollars.By contrast, some non-scientific studies, including one conducted by Philip Morris in the Czech Republic called Public Finance Balance of Smoking in the Czech Republic and another by the Cato Institute, support the opposite position. Philip Morris has explicitly apologised for the former study, saying: "The funding and public release of this study which, among other things, detailed purported cost savings to the Czech Republic due to premature deaths of smokers, exhibited terrible judgment as well as a complete and unacceptable disregard of basic human values. For one of our tobacco companies to commission this study was not just a terrible mistake, it was wrong. All of us at Philip Morris, no matter where we work, are extremely sorry for this. No one benefits from the very real, serious and significant diseases caused by smoking."Between 1970 and 1995, per-capita cigarette consumption in poorer developing countries increased by 67 percent, while it dropped by 10 percent in the richer developed world. Eighty percent of smokers now live in less developed countries. By 2030, the World Health Organization (WHO) forecasts that 10 million people a year will die of smoking-related illness, making it the single biggest cause of death worldwide, with the largest increase to be among women. WHO forecasts the 21st centurys death rate from smoking to be ten times the 20th centurys rate ("Washingtonian" magazine, December 2007).
The tobacco industry is known to be one of the largest global enterprises in the world. The six biggest tobacco companies made a combined profit of $35.1 billion (Jha et al., 2014) in 2010.

Social
Famous smokers of the past used cigarettes or pipes as part of their image, such as Jean-Paul Sartres Gauloises-brand cigarettes; Albert Einsteins, Douglas MacArthurs, Bertrand Russells, and Bing Crosbys pipes; or the news broadcaster Edward R. Murrows cigarette. Writers in particular seem to be known for smoking, for example, Cornell Professor Richard Kleins book Cigarettes are Sublime for the analysis, by this professor of French literature, of the role smoking plays in 19th and 20th century letters. The popular author Kurt Vonnegut addressed his addiction to cigarettes within his novels. British Prime Minister Harold Wilson was well known for smoking a pipe in public as was Winston Churchill for his cigars. Sherlock Holmes, the fictional detective created by Sir Arthur Conan Doyle, smoked a pipe, cigarettes, and cigars. The DC Vertigo comic book character John Constantine, created by Alan Moore, is synonymous with smoking, so much so that the first storyline by Preacher creator Garth Ennis centered around John Constantine contracting lung cancer. Professional wrestler James Fullington, while in character as "The Sandman", is a chronic smoker in order to appear "tough".
The problem of smoking at home is particularly difficult for women in many cultures (especially Arab cultures), where it may not be acceptable for a woman to ask her husband not to smoke at home or in the presence of her children. Studies have shown that pollution levels for smoking areas indoors are higher than levels found on busy roadways, in closed motor garages, and during fire storms. Furthermore, smoke can spread from one room to another, even if doors to the smoking area are closed.The ceremonial smoking of tobacco, and praying with a sacred pipe, is a prominent part of the religious ceremonies of a number of Native American Nations. Sema, the Anishinaabe word for tobacco, is grown for ceremonial use and considered the ultimate sacred plant since its smoke is believed to carry prayers to the spirits. In most major religions, however, tobacco smoking is not specifically prohibited, although it may be discouraged as an immoral habit. Before the health risks of smoking were identified through controlled study, smoking was considered an immoral habit by certain Christian preachers and social reformers. The founder of the Latter Day Saint movement, Joseph Smith, recorded that on 27 February 1833, he received a revelation which discouraged tobacco use. This "Word of Wisdom" was later accepted as a commandment, and faithful Latter-day Saints abstain completely from tobacco. Jehovahs Witnesses base their stand against smoking on the Bibles command to "clean ourselves of every defilement of flesh" (2 Corinthians 7:1). The Jewish Rabbi Yisrael Meir Kagan (1838–1933) was one of the first Jewish authorities to speak out on smoking. In Ahmadiyya Islam, smoking is highly discouraged, although not forbidden. During the month of fasting however, it is forbidden to smoke tobacco. In the Baháʼí Faith, smoking tobacco is discouraged though not forbidden.

Public policy
On 27 February 2005 the WHO Framework Convention on Tobacco Control, took effect. The FCTC is the worlds first public health treaty. Countries that sign on as parties agree to a set of common goals, minimum standards for tobacco control policy, and to cooperate in dealing with cross-border challenges such as cigarette smuggling. Currently the WHO declares that 4 billion people will be covered by the treaty, which includes 168 signatories. Among other steps, signatories are to put together legislation that will eliminate secondhand smoke in indoor workplaces, public transport, indoor public places and, as appropriate, other public places.

Taxation
Many governments have introduced excise taxes on cigarettes in order to reduce the consumption of cigarettes. The World Health Organisation finds that:
The structure of tobacco excise taxes varies considerably across countries, with lower income countries more likely to rely more on ad valorem excises and higher income countries more likely to rely more on specific excise taxes, while many countries at all income levels use a mix of specific and ad valorem excises.
Tobacco excise tax systems are quite complex in several countries, where different tax rates are applied based on prices, product characteristics such as presence/absence of a filter or length, packaging, weight, tobacco content, and/or production or sales volume. These complex systems are difficult to administer, create opportunities for tax avoidance, and are less effective from a public health perspective.

Globally, cigarette excise taxes account for less than 45 percent of cigarette prices, on average, while all taxes applied to cigarettes account for just over half of half of price. Higher income countries levy higher taxes on tobacco products and these taxes account for a greater share of price, with both the absolute tax and share of price accounted for by tax falling as country incomes fall.
In 2002, the Centers for Disease Control and Prevention said that each pack of cigarettes sold in the United States costs the nation more than $7 in medical care and lost productivity, around $3400 per year per smoker. Another study by a team of health economists finds the combined price paid by their families and society is about $41 per pack of cigarettes.Substantial scientific evidence shows that higher cigarette prices result in lower overall cigarette consumption. Most studies indicate that a 10% increase in price will reduce overall cigarette consumption by 3% to 5%. Youth, minorities, and low-income smokers are two to three times more likely to quit or smoke less than other smokers in response to price increases. Smoking is often cited as an example of an inelastic good, however, i.e. a large rise in price will only result in a small decrease in consumption.
Many nations have implemented some form of tobacco taxation. As of 1997, Denmark had the highest cigarette tax burden of $4.02 per pack. Taiwan only had a tax burden of $0.62 per pack. The federal government of the United States charges $1.01 per pack.Cigarette taxes vary widely from state to state in the United States. For example, Missouri has a cigarette tax of only 17 cents per pack, the nations lowest, while New York has the highest cigarette tax in the U.S.: $4.35 per pack. In Alabama, Illinois, Missouri, New York City, Tennessee, and Virginia, counties and cities may impose an additional limited tax on the price of cigarettes. Sales taxes are also levied on tobacco products in most jurisdictions.
In the United Kingdom, a packet of 20 cigarettes has a tax added of 16.5% of the retail price plus £4.90. The UK has a significant black market for tobacco, and it has been estimated by the tobacco industry that 27% of cigarette and 68% of handrolling tobacco consumption is non-UK duty paid (NUKDP).In Australia total taxes account for 62.5% of the final price of a packet of cigarettes (2011 figures). These taxes include federal excise or customs duty and Goods and Services Tax.

Restrictions
In June 1967, the US Federal Communications Commission ruled that programmes broadcast on a television station which discussed smoking and health were insufficient to offset the effects of paid advertisements that were broadcast for five to ten minutes each day. In April 1970, the US Congress passed the Public Health Cigarette Smoking Act banning the advertising of cigarettes on television and radio starting on 2 January 1971.The Tobacco Advertising Prohibition Act 1992 expressly prohibited almost all forms of Tobacco advertising in Australia, including the sponsorship of sporting or other cultural events by cigarette brands.
All tobacco advertising and sponsorship on television has been banned within the European Union since 1991 under the Television Without Frontiers Directive (1989). This ban was extended by the Tobacco Advertising Directive, which took effect in July 2005 to cover other forms of media such as the internet, print media, and radio. The directive does not include advertising in cinemas and on billboards or using merchandising – or tobacco sponsorship of cultural and sporting events which are purely local, with participants coming from only one Member State as these fall outside the jurisdiction of the European Commission. However, most member states have transposed the directive with national laws that are wider in scope than the directive and cover local advertising. A 2008 European Commission report concluded that the directive had been successfully transposed into national law in all EU member states, and that these laws were well implemented.Some countries also impose legal requirements on the packaging of tobacco products. For example, in the countries of the European Union, Turkey, Australia and South Africa, cigarette packs must be prominently labeled with the health risks associated with smoking. Canada, Australia, Thailand, Iceland and Brazil have also imposed labels upon cigarette packs warning smokers of the effects, and they include graphic images of the potential health effects of smoking. Cards are also inserted into cigarette packs in Canada. There are sixteen of them, and only one comes in a pack. They explain different methods of quitting smoking. Also, in the United Kingdom, there have been a number of graphic NHS advertisements, one showing a cigarette filled with fatty deposits, as if the cigarette is symbolizing the artery of a smoker.
Some countries have also banned advertisement at point of sale. United Kingdom and Ireland have limited the advertisement of tobacco at retailers. This includes storing of cigarettes behind a covered shelf not visible to the public. They do however allow some limited advertising at retailers. Norway has a complete ban of point of sale advertising. This includes smoking products and accessories. Implementing these policies can be challenging, all of these countries experienced resistance and challenges from the tobacco industry. The World Health Organisation recommends the complete ban of all types of advertisement or product placement, including at vending machines, at airports and on internet shops selling tobacco. The evidence is as yet unclear as to the impact of such bans.
Many countries have a smoking age. In many countries, including the United States, most European Union member states, New Zealand, Canada, South Africa, Israel, India, Brazil, Chile, Costa Rica and Australia, it is illegal to sell tobacco products to minors and in the Netherlands, Austria, Belgium, Denmark and South Africa it is illegal to sell tobacco products to people under the age of 16. On 1 September 2007 the minimum age to buy tobacco products in Germany rose from 16 to 18, as well as in the United Kingdom where on 1 October 2007 it rose from 16 to 18. Underlying such laws is the belief that people should make an informed decision regarding the risks of tobacco use. These laws have a lax enforcement in some nations and states. In China, Turkey, and many other countries usually a child will have little problem buying tobacco products, because they are often told to go to the store to buy tobacco for their parents.
Several countries such as Ireland, Latvia, Estonia, the Netherlands, Finland, Norway, Canada, Australia, Sweden, Portugal, Singapore, Italy, Indonesia, India, Lithuania, Chile, Spain, Iceland, United Kingdom, Slovenia, Turkey and Malta have legislated against smoking in public places, often including bars and restaurants. Restaurateurs have been permitted in some jurisdictions to build designated smoking areas (or to prohibit smoking). In the United States, many states prohibit smoking in restaurants, and some also prohibit smoking in bars. In provinces of Canada, smoking is illegal in indoor workplaces and public places, including bars and restaurants. As of 31 March 2008 Canada has introduced a smoke-free law in all public places, as well as within 10 metres of an entrance to any public place. In Australia, smoke-free laws vary from state to state. Currently, Queensland has completely smoke-free indoor public places (including workplaces, bars, pubs and eateries) as well as patrolled beaches and some outdoor public areas. There are, however, exceptions for designated smoking areas. In Victoria, smoking is restricted in railway stations, bus stops and tram stops as these are public locations where second-hand smoke can affect non-smokers waiting for public transport, and since 1 July 2007 is now extended to all indoor public places. In New Zealand and Brazil, smoking is restricted in enclosed public places including bars, restaurants and pubs. Hong Kong restricted smoking on 1 January 2007 in the workplace, public spaces such as restaurants, karaoke rooms, buildings, and public parks (bars which do not admit minors were exempt until 2009). In Romania smoking is illegal in trains, metro stations, public institutions (except where designated, usually outside) and public transport. In Germany, in addition to smoking bans in public buildings and transport, an anti-smoking ordinance for bars and restaurants was implemented in late 2007. A study by the University of Hamburg (Ahlfeldt and Maennig 2010) demonstrates, that the smoking ban had, if any, only short run impacts on bar and restaurant revenues. In the medium and long run no negative effect was measurable. The results suggest either, that the consumption in bars and restaurants is not affected by smoking bans in the long run, or, that negative revenue impacts by smokers are compensated by increasing revenues through non-smokers.

Ignition safety
An indirect public health problem posed by cigarettes is that of accidental fires, usually linked with consumption of alcohol. Enhanced combustion using nitrates was traditionally used but cigarette manufacturers have been silent on this subject claiming at first that a safe cigarette was technically impossible, then that it could only be achieved by modifying the paper. Roll your own cigarettes contain no additives and are fire safe. Numerous fire safe cigarette designs have been proposed, some by tobacco companies themselves, which would extinguish a cigarette left unattended for more than a minute or two, thereby reducing the risk of fire. Among American tobacco companies, some have resisted this idea, while others have embraced it. RJ Reynolds was a leader in making prototypes of these cigarettes in 1983 and will make all of their U.S. market cigarettes to be fire-safe by 2010 </s>