Review your respirator cartridge change schedule

If your employees use respirators, OSHA requires you to provide a respirator cartridge change schedule, unless the respirator includes an end-of-service-life indicator (ESLI) certified by the National Institute for Occupational Safety and Health (NIOSH). Respirator cartridges beyond their service life will not protect workers.

A change schedule is part of the written respirator program which explains how often workers should replace cartridges and what information the employer used to make that judgment.

The service life of a cartridge depends on many factors including environmental conditions, breathing rate, cartridge filtering capacity, and the amount of contaminants in the air. Employers should apply a safety factor to the estimated service life so the change schedule offers a conservative estimate.

Creating a change schedule

When employers must develop change schedules, the standard covers the following requirements.

• Employers must develop cartridge/canister change schedules based on available data or information. This includes the exposure assessment and information based on breakthrough test data, mathematically based estimates, and/or reliable use recommendations from the respirator supplier or chemical supplier.
• OSHA emphasizes using a conservative approach when evaluating service life testing data. Temperature, humidity, air flow through the filter, the work rate, and other potential interfering chemicals can all affect the service life of an air-purifying cartridge or canister.

If you know the chemical used and the exposure level, you can estimate how long a respirator cartridge will work and apply the safety factor. There are three valid ways to estimate a cartridge’s service life, each with pros and cons.

1. Conduct experimental tests
   • PRO: Can save money by providing a more accurate service life value instead of relying on conservative assumptions made by other methods.
   • PRO: Most reliable method, especially for multiple contaminants.
   • PRO: Can be used to validate an existing change schedule.
   • CON: Will likely take time and money to perform the tests.
2. Use the manufacturer's recommendation
   • PRO: Provides a more accurate estimate for a specific brand of respirator.
   • PRO: Relies on the manufacturer’s broad knowledge and expertise.
   • CON: May not be possible if the manufacturer cannot provide a recommendation.
   • CON: May not account for all workplace and user factors.
3. Use a math model
   • PRO: Inexpensive and takes little time.
   • PRO: Requires no calculations if you use NIOSH's MultiVapor™ Version 2.2.3 Application.
   • CON: Not as accurate as experimental testing. May result in a shorter service life estimate due to conservative assumptions.
   • CON: Generally limited to single contaminant situations.

Other considerations

Do not rely on odor thresholds and other warning properties as the primary basis for determining the service life of gas and vapor cartridges and canisters.

Account for environmental and user factors and use a conservative approach when evaluating service life testing data. Apply a safety factor to any estimate to account for uncertainty.

Mixtures, intermittent use and concentrations, storage practices, and other variables may require adopting an administrative time limit, potentially as short as one day, even if the estimated life would be longer.