What condition must be met for the Incident Commander to authorize the use of the air-purifying respirator?

For the Incident Commander to authorize the use of an air-purifying respirator, the air contaminant must have been identified. This is crucial because air-purifying respirators are designed to filter out specific contaminants from the air, and without knowing what the contaminant is, there's no way to ensure the right type of respirator is being used. Identifying the contaminant allows responders to select the appropriate filter cartridge that will effectively purify the air and protect users from exposure.

Utilizing air-purifying respirators in the absence of identifying the contaminants can lead to inadequate protection, which could endanger personnel. Proper identification is part of the risk assessment that ensures occupational safety and health standards are upheld during hazardous situations.