How do I conduct air monitoring in a confined space?
First, air monitoring should be conducted from outside of the confined space. A pump may be necessary to draw air from the space. All levels of the confined space should be checked - the top, mid-section, and bottom. Gases can be lighter than air, heavier than air, or similar to air. Testing all levels of a space ensures that all gases are detected.
Continuous air monitoring is a best practice and should be used whenever possible. It is required where ventilation is the control method for a potentially hazardous atmosphere (i.e. initial air monitoring indicated conditions unacceptable for entry).