Air-Purifying Respirator No. 2: Gas and Vapor Respirators

The second type of air-purifying respirator is the gas and vapor respirator. Gas and vapor respirators are typically for situations involving hazardous gases and vapors in the air.

The respirator uses chemical filters (known as cartridges or canisters) that remove dangerous gases or vapors. Gas and vapor respirators do not protect against airborne particles.

These respirators have an absorption capacity. They do not provide protection if this is depleted. The time until depletion (often referred to as service life) depends on many factors, including the following:

• Environmental conditions
• Breathing rate
• Cartridge filtering capacity
• The amount of contaminants in the air

For this reason, OSHA has a page dedicated to Respirator Change Schedules.

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