We need to talk. Every year we use Valentine’s Day as an opportunity to talk about our love for respirators and personal protective equipment (PPE). We’ve had some good times frolicking through the standards and maintenance requirements. But today we need to address what happens when it’s just not working anymore. We have to discuss the end-of-service-life of your respirator’s cartridges or canisters.

End-of-service-life is when a respirator can no longer provide the expected level of protection to the user. Hey, we’ve all been there. Your filter medium is clogged. Breathing while wearing the respirator may have become difficult; or the sorbent, when protecting against gases or vapors, has reached its capacity and can no longer capture and retain harmful contaminants. Or, this may be when the respirator becomes damaged, soiled, or its integrity is no longer intact. You don’t have to put up with that. In fact, for the sake of your safety, you should never put up with that. According to the Occupational Safety and Health Administration (OSHA), the federal agency in charge of setting and enforcing occupational safety and health standards,

“The service life of a cartridge [or canister] depends upon many factors, including environmental conditions, breathing rate, cartridge filtering capacity, and the amount of contaminants in the air. It is suggested that employers apply a safety factor to the service life estimate to assure that the change schedule is a conservative estimate.”

So how do you know when it’s really over?

When it comes to air-purifying respirators that offer particulate protections, you should inspect the outside of the filter material before each use. If the filter material is physically damaged or soiled, the filter should be changed (in the case of respirators with replaceable filters) or the respirator discarded (in the case of filtering facepiece respirators). Your respiratory protection program administrator should always follow the respirator filter manufacturer’s service-time-limit recommendations.

According to the OSHA regulations, employers are required to provide a respirator cartridge change schedule. A change schedule is the part of the written respirator program that explains how often the cartridges you use in your specific respirator model (against specific contaminants) should be replaced. Usually, respirator manufacturers also have software to estimate a change schedule for their cartridges/ canisters. Cartridge/canister change schedules are not the same from one manufacturer to another.

Some gas- and vapor-removing air-purifying respirators are also equipped with passive end-of-service-life indicators (ESLIs). The ESLI is usually specific to only one contaminant. The ESLI gives the wearer an indication, often a color change, that the contaminant will no longer be sufficiently removed by the cartridge/canister and that the cartridge/canister should be replaced.

However, ESLI could be affected by the conditions in the work environment. The OSHA regulation exists to ensure the filter change happens in the event that the ESLI doesn’t function properly. The ESLI can be used as a change indicator if conditions allow, which adds a safety margin to the change schedule. The indicator will change color prior to the end of the cartridge life. If conditions do not allow the ESLI to function properly or if multiple gases are present, and the ESLI is an indicator for only one of those gases, OSHA requires that a change schedule be the primary method of keeping track of your cartridge’s/canister’s lifespan.

Additionally, OSHA has mandatory use limits and exposure limits for certain substances like acrylonitrile, benzene, butadiene, formaldehyde, vinyl chloride, and methylene chloride. Workers depending on respiratory protection who are exposed to any of these contaminants at or above the OSHA Permissible Exposure Limit (PEL) must change cartridges/canisters according to OSHA’s requirements.

Workers should always consult their Respirator Program Administrator regarding when to change their canisters/cartridges.

Additional Resources:

OSHA provides guidance on using mathematical models to predict the service life of organic vapor respirator cartridges when used for protection against single contaminants.

Your respiratory protection program administrator can calculate others using a computer program called Advisor Genius. OSHA suggests that you reduce the service life estimate by some safety factor and document the change schedule in your written respiratory program.

NIOSH has developed a MultiVapor Application, which is a computer tool for estimating breakthrough times and service lives of air-purifying respirator cartridges manufactured to remove toxic organic vapors from breathed air that can be used with the cartridge/canister manufacturer’s recommendations for multi-gas use of the specific canister/cartridge being used.

OSHA website on valid ways to estimate your cartridge’s service life

Sometimes it has to happen … out with the old cartridges and in with the new. This breakup should have you singing I Will Survive. Because – you got all your life to live and you got all your love to give; that’s exactly why proper respiratory protection is important.

So, don’t drag your feet when it comes to changing your respirator cartridges/canisters, especially if you experience odor or irritation, which would indicate that your respirator is not functioning adequately. Consult your respiratory protection program administrator who should be following the respirator manufacturer’s recommendations as well as OSHA regulations.

Source: National Institute for Occupational Safety and Health (NIOSH)