In the upper atmosphere, ozone shields the Earth from ultraviolet rays. But lower down, it can be harmful to respiratory systems, and in recent years scientists have documented increases in heart problems associated with ozone.
Not just an unsightly blight.
That’s all bad news for Houston, of course, because it regularly has the second-worst ozone pollution behind only Los Angeles. According to one state agency, each year, millions of people in the greater Houston area are exposed to unhealthy levels of ozone at one point or another.
But what scientists didn’t really know, until now, is how the inhaled pollutant caused damage. A new study in mice may have found the answer, that inhaled ozone impairs the body’s immune system. From a summary:
The Duke-led team found that ozone exposure in mice at levels approximating unhealthy levels for humans appears to enhance lung injury in response to bacterial toxins, but more importantly, it also appears to enhance programmed cell death in critical innate immune system cells that gobble up foreign invaders, keeping the airways clear.
“Small amounts of inhaled foreign material can be relatively harmless, since they stimulate an appropriate innate immune response that protects the lungs,” said John Hollingsworth, M.D., pulmonologist and lead author of a study whose results appear Oct. 1 in the Journal of Immunology. “However, it appears that ozone causes the innate immune system to overreact, killing key immune system cells, and possibly making the lung more susceptible to subsequent invaders, such as bacteria.”
The innate immune system is the most primitive aspect of the body’s defenses. Its cells react indiscriminately to any invader. One of the key cells in the innate immune system is known as a macrophage, Greek for “big eater.”
Officials say Houston’s ozone levels should exceed federal clean air standards until at least 2018.