Atmospheric Testing Protocol
An Atmospheric Testing Protocol is a formal, written, and repeatable procedure for assessing, recording, and controlling the atmosphere in confined spaces or hazardous work areas. It verifies oxygen levels (19.5%-23.5%), flammability (≤10% LEL), and toxic contaminants (e.g., CO ≤25 ppm, H₂S ≤10 ppm) against regulatory limits before and during worker exposure, as required by WorkSafeBC Part 9 & 22 and OSHA 29 CFR 1910.146.
On a manufacturing shop floor, the Atmospheric Testing Protocol is embedded in the Confined Space Entry Program and Permit System. Before entry into tanks, pits, silos, or process vessels, pre-entry testing must verify hazard controls are effective. Testing is required within 20 minutes before initial entry and repeated if workers vacate for over 20 minutes. For moderate/high hazard atmospheres, continuous monitoring is mandatory. The protocol specifies testing order: oxygen first, then combustible gases, then toxics. Testing must occur at multiple levels (e.g., every 5 ft) to detect stratified atmospheres. Results are recorded on the entry permit, including instrument calibration status, time, location, and readings. If readings are unacceptable, entry is aborted until the cause is remedied.
How does WorkSafeBC distinguish 'low hazard' atmospheres, and when can pre-entry atmospheric testing be omitted?
A low hazard atmosphere is clean respirable air (approx. 20.9% oxygen, no measurable flammable gas/vapour, no contaminant exceeding 10% of its Part 5 exposure limit) that is not likely to change during work. Pre-entry testing can be omitted only if the space's location and controls ensure a more hazardous atmosphere cannot develop, and written procedures explicitly do not require testing. This is narrow; most industrial spaces with chemical residues or process gases should still be tested.
What are the specific WorkSafeBC atmospheric testing requirements for underground workings?
WorkSafeBC Part 22 requires tests for oxygen deficiency, air contaminants (per Part 5 exposure limits), and respirable combustible dust (≤1.5 mg/m³ 8-hr TWA). Tests for CO, NO₂, combustible gases, and oxygen are required if ventilation is interrupted >1 hour, at least every 4 hours when internal combustion engines operate, after blasting, after a fire, or as directed by a WorkSafeBC officer. Tests must be conducted by a qualified person using Board-acceptable equipment, with results recorded in the Underground Record.
How do OSHA's 'evaluation' and 'verification' atmospheric tests differ?
Evaluation testing characterizes all hazardous atmospheres that may exist or arise, using instruments with sufficient sensitivity to identify contaminants, and determines acceptable entry conditions. Verification testing confirms that at the time of entry, actual concentrations are within those acceptable conditions, using permit-specified equipment. Results of verification testing must be recorded on the permit adjacent to acceptable entry conditions.