Four Little Words Too Many Employers Overlook

OSHA Requires Cartridge & Canister Change Schedules

March 2, 2015 – “Objective information or data”.  At first glance, these four little words plucked from a passage in the middle of OSHA’s respiratory protection standard are easy to overlook or misinterpret. But any employer who fails to carefully read and understand what is required to comply with 1910.134(d)(3)(iii)(B)(2) will not only be setting themselves up for an OSHA citation with a hefty penalty, they might also be putting the health and safety of their workers at risk!

This section of the Federal OSHA respiratory protection standard applies when there is no substance-specific standard and no appropriate end-of-service-life indicator (ESLI) for the cartridges and/or canisters used on air-purifying respirators to protect workers against excessive exposures to gases and vapors. When this is the case, OSHA requires the employer to implement a change schedule for those canisters and cartridges that is based on objective information or data that will ensure that canisters and cartridges are changed before the end of their service life. The employer must also describe in their written respirator program the information and data relied upon and the basis for the canister and cartridge change schedule and the basis for reliance on the data. I briefly touched on this topic in a previous post about the most common violations I find during my reviews of employers’ respiratory protection programs, but I felt the need to expand on this particular issue due to the large percentage of employers I find who simply do not have a clue what is required of them.

What is meant by “objective information or data”?  Let me begin by stating what it does NOT mean. It does NOT mean telling your workers to change their cartridges and canisters as soon as they can taste or smell the chemicals breaking through. Although this method was considered acceptable under the old respiratory protection standard, the updated version (1998) disallowed it, based on the reasoning that once break-through of the chemical(s) had occurred, the respirator user may have already been overexposed. Furthermore, some chemicals cannot even be detected by odor or taste at potentially harmful levels. “Objective information and data” also does NOT mean “playing it safe” by arbitrarily requiring workers to change their cartridges or canisters at the end of every shift, as I see many employers relying on to protect their employees.  While it is certainly possible workers changing their cartridges or canisters at the end of each shift are doing so before they are over-loaded (in some cases, even way before), it is also very possible they are being changed too late, after over-exposure has already occurred. So implementing a subjective change-out schedule such as “at the end of every shift” is not acceptable either.

So, what does OSHA require affected employers to do? They must develop a work-site-specific cartridge and/or canister change-out schedule that is based on numerous factors that can affect how long each device can be used before it must be replaced. And the method and data used to develop the change-out schedule must be included in the employers written respiratory protection program. Variables that go into making the decision of when cartridges and canisters must be changed out include, but are not limited to, the type(s) and concentration(s) of contaminant(s) present in the worker’s breathing zone, the properties of the chemical(s) being used, temperature and humidity levels in the work area, and the level of work effort expended by the respirator user (which affects their breathing rate). Manufacturers’ of most respirator cartridges and canisters available for protection against gases and vapors have formulas posted on their websites, where estimates of these and other critical factors are entered (see 3M’s; see MSA’s). NIOSH also provides a model on their website. After entering and processing the data in one of these programs, the result is a schedule for the maximum time allowed for use of the cartridge or canister before it must be changed under these workplace conditions.

Be aware that there are several other methods available that employers could use to develop a cartridge and/or canister change-out schedule. One method would be to have a qualified person experiment with simulated atmospheric conditions from the workplace inside of a controlled laboratory environment, and then analyzing exposed cartridges to determine break-through times based on worst-case scenarios. And really, really smart people can even develop change-out schedules based on mathematical models that predict cartridge break-through times; OSHA even provides an e-Tool on their website that can help you do this. But the most straight-forward, realistic method seems to me to be the use of manufacturers’ formulas specifically developed for their particular cartridges and/or canisters.

Keep in mind that a change-out schedule will most likely need to be developed for the different brands and sizes of respirator cartridges and canisters inn use, as well as for your various work areas that represent different chemical exposures. So it will not be an easy task that can be quickly knocked out. For example, an employer might need to utilize an industrial hygienist or qualified safety professional to conduct an air survey (a service offered free by many workers comp insurance carriers) of each operation where workers are exposed to gases and vapors to determine their average exposure(s) for the chemical(s) to which they are exposed so meaningful data can be entered into the manufacturer’s formula. In addition, measurements and/or estimates of variables such as work rate and weather conditions will need to be gathered for each operation, as changes can greatly impact cartridge break-through times (for example, increased temperatures greatly affect chemical evaporation rates, and therefore cartridge loading occurs much quicker).

A great resource with more information about how to comply with this standard can be found in the OSHA Compliance Directive CPL 02-00-158, Inspection Procedures for the Respiratory Protection Standard, published in June of 2014. Refer to page 19, paragraph 6 for information on change schedules, as well as in Appendix B of the document. Also, please note that this requirement does NOT apply to air-purifying filters used to protect workers from particulate(s); only to gas and vapor cartridges and canisters.

In closing, I will say that the vast majority of employers I have audited who had employees using cartridges or canisters to protect against over-exposure to gases and vapors have not developed the mandatory cartridge and canister change-out schedule as required by OSHA. And of the few who had, many failed to keep their change-out schedules up-to-date as operations and/or equipment changed over time. But any failure on the part of the employer to take the time to develop and/or update a respirator cartridge and/or canister change-out schedule for their operations could put their workers’ health, and their own pocket-books, at risk.

Have you developed (or help develop) a respirator cartridge and/or canister change-out schedule before? What method did you use to develop the schedule? How did you document the data and information in your written respiratory protection program? Did you find the experience to be easy, or difficult? Perhaps you have some information about this topic that you’d like to share? If you do, or would like to read comments submitted by others, please click here and enter your information in the “Comments” box. And last but not least, I would like to encourage you to share this Blog post with others in your network who might benefit from reading this information.



Curtis Chambers is a Certified Safety Professional (CSP) and holds a Master of Science degree in Occupational Safety and Health. He has held numerous leadership positions managing and evaluating health and safety programs and providing training on workplace safety and health topics at various public organizations and private corporations. Mr. Chambers is currently the President of OSHA Training Services Inc. Visit their website at  
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