Respirator Trusted-Source Information
Section 3: Ancillary Respirator Information
What is end-of-service-life?
End-of-service-life is when a respirator no longer works correctly. It is when the filtering medium can no longer provide the expected level of protection from harmful air contaminants, has reached its capacity for capture and retention of the contaminant, when breathing while wearing the respirator becomes too difficult, or when the respirator becomes damaged, contaminated, or the integrity of the respirator is no longer intact.
Do respirators have end-of-service-life indicators on them?
Yes. Some do, for others like the N95 the “indicator” may be the appearance, whether the respirator is damaged, contaminated with visible blood or body fluids, or misshapen. For other types of respirators there are specific indicators integral in the device. All self-contained breathing apparatuses have an alarm that tells the wearer that he/she is going to run out of air from his cylinder and he/she must leave the contaminated area. Some gas- and vapor-removing air-purifying respirators are also equipped with end-of-service-life indicators (ESLI). The ESLI are usually specific to only one contaminant. The ESLI gives the wearer an indication, often a color change, that the contaminant will no longer be able to be removed by the cartridge or canister and that the cartridge or canister should be replaced.
What is the service life of an N95 filter or filtering facepiece respirator?
Unless the manufacturer identifies a specified duration of use, for example “single use only”, the service life of all filters is limited by considerations of hygiene, damage, and breathing resistance. All filters should be replaced whenever they are damaged, soiled, or causing noticeably increased breathing resistance. Follow manufacturer’s recommendations for specific information on the model you are using.
How is a cartridge change out schedule calculated?
In the absence of an ESLI, a cartridge/canister change out schedule is required for gas- and vapor-removing respirators and should be based on objective information or data that will ensure that canisters and cartridges are changed before the end of their service life. Usually, manufacturers have software to estimate a change out schedule for their cartridges or canisters. Changeout schedules are not the same from one manufacturer’s cartridges or canisters to that of another manufacturer. This is because the volume and type of adsorbent varies between manufacturers. Additionally, the Occupational Safety and Health Administration (OSHA) has mandatory changeout schedules for cartridges 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. In any case, workers should consult their Respirator Program Administrator regarding when to change their cartridges/canisters.
OSHA provides guidance on using mathematical models to predict the service life of organic vapor respirator cartridges when used for protection against single contaminants. You can also find the service lives for respirator cartridges intended to protect against selected gases already calculated in a table. You 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.
OSHA has no accepted way to determine a cartridge’s service life when exposed to mixtures; computer models have been developed that can estimate service life if you know all the canister physical attributes, environmental factors, contaminants and levels, and work rates [Note: Other research has been conducted to develop models for contaminant mixtures, but they have not yet been adopted by OSHA.] NIOSH has developed 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.
If respirators are required in your workplace, OSHA mandates that your employer establish and maintain a respiratory protection program that must describe the information and data relied upon and the basis for the canister and cartridge change schedule. Because of the complexity of factors involved in determining canister changeout schedules, consult your Respirator Program Administrator.
Is canister/cartridge end-of-service life information available on the manufacturers’ website?
Most manufacturers provide information on their website to help in determining the appropriate changeout schedule for their product.
If I am using a combination cartridge with a PAPR, how do I know when to change the cartridge? Can the cartridge be decontaminated to extend its useful life?
The training you receive in the use of your assigned respirator as part of your employer’s respiratory protection plan will tell you the frequency of cartridge change that has been determined to be appropriate for the conditions in your worksite. The Occupational Safety and Health Administration’s Standard for Respiratory Protection (29 CFR 1910.134) requires employers to implement a change schedule for all cartridges used in the workplace for protection against vapors and gases when there isn't an end-of-service- life indicator on the cartridge. This schedule must be site specific and take into consideration worksite conditions such as humidity, worker breathing rate, as well as the contaminants and their concentrations.
The cartridge can’t be decontaminated (i.e. reconditioned for reuse). The filter media in the cartridge has a finite capacity and the mechanism used to remove the contaminants from the air is usually not reversible.
Why do we need to change the respirator cartridge before we can smell something?
The purpose of this is to prevent contaminants from breaking through the respirator's sorbent (filtering) cartridge(s), and thereby exposing the wearer. Historically, respirator wearers have relied on the warning properties (e.g., odor, irritation) of a contaminant as a means to determine when it is time for replacing used cartridges. OSHA no longer allows the use of warning properties as the primary basis for changing respirator cartridges. The following factors shall be considered when developing a Respirator Cartridge Change Schedule which is required by OSHA and should be documented in the Respirator Protection Program:
- Frequency of use (e.g., continuously, intermittently) throughout the shift
- Wearer’s work rate
- The presence of potentially interfering chemicals
Do we need to throw a filter (used with a PAPR) away when used for/with an H1N1 patient for only one hour?
Powered air purifying respirator filters used for protection against viruses have no time limit as to their ability to remove viruses from the air stream. Their use is subject to other considerations by the infection control or safety officer in the healthcare facility. Therefore, it is recommended there be written facility standards for use and disposal of these filters. However, filters and cartridges cannot be cleaned, sanitized, or disinfected and should be properly disposed of after use.
At this time, neither the Centers for Disease Control and Prevention (CDC) nor the World Health Organization (WHO) have provided any recommendations for cleaning, sanitizing, or disinfecting respirators used for novel H1N1 virus exposures. The Occupational Safety and Health Administration (OSHA) requires respirator users to follow either the respirator manufacturer’s instructions or OSHA’s general procedures for cleaning respirators in 29 CFR 1910.134 Appendix B-2; however, OSHA’s procedures are not specific for novel H1N1 virus and may not lead to disinfection.
Refer to the User Instructions for the specific PAPR unit and headgear to identify the components that can be cleaned.
- Page last reviewed: December 10, 2014
- Page last updated: August 3, 2011
- Content source:
- National Institute for Occupational Safety and Health National Personal Protective Technology Laboratory