Confined Space Air Monitoring
When is it necessary to conduct atmospheric testing?
The plan must contain provisions for atmospheric testing. The
atmospheric hazards of concern include oxygen content outside the
acceptable range of 19.5 to 23%, the potential accumulation of flammable,
combustible, or explosive agents, or accumulation of atmospheric
Who is responsible for performing atmospheric testing and for what
The employer must appoint a person with adequate knowledge, training
and experience to perform adequate tests.
What are some of the requirements of atmospheric testing?
The selection of testing equipment will depend on the circumstances of
the confined space, the nature of the work within the space, and
knowledge of possible atmospheric hazards. Whenever practical,
continuous monitoring should be considered.
What is meant by "calibrated instruments that are in good working
order and are appropriate for the hazards identified in the relevant
The testing instrument must be selected and calibrated for the specific
atmospheric hazards likely to be present in the space as identified in the
Continuous monitoring is required:
when performing hot work in a confined space that contains or is likely to
contain an explosive or flammable gas or vapour.
when the atmosphere in the confined space has been rendered inert by
adding an inert gas, or as set out in the confined space plan.
Workers must be actually aware of the levels they are encountering and
aware of any fluctuation that may be occurring in order to warn them of
any unusual conditions as they develop. Monitors may have alarms;
however, depending at what level they are set, they may not give the
workers adequate warning of fluctuations or increases in atmospheric
levels that should be investigated.
In general, the employer must retain atmospheric testing records for the
longer of the following periods: one year after the document is created; or,
the period that is necessary to ensure that at least the two most recent
records of each kind that relate to a particular confined space are retained.
Use the Risk Charts
Use the Risk Charts