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Short answer
A respirator cartridge is a replaceable container of sorbent, filter or catalyst that fits an air-purifying respirator and removes specific gases or vapors from the air a wearer breathes. Particulate filters such as N95 and P100 remove aerosols instead. A cartridge’s colour band shows what it is built for, but under OSHA’s respirator standard the respirator must also be NIOSH-certified and used within the conditions of that certification.
What is a respirator cartridge, and how is it different from a filter or canister?
OSHA’s respiratory protection standard, 29 CFR 1910.134, defines an air-purifying respirator as one “with an air-purifying filter, cartridge, or canister that removes specific air contaminants by passing ambient air through the air-purifying element.” The same standard defines a canister or cartridge as “a container with a filter, sorbent, or catalyst, or combination of these items, which removes specific contaminants from the air passed through the container,” and defines a filter, or air-purifying element, as “a component used in respirators to remove solid or liquid aerosols from the inspired air.”
Read together, those definitions give a working split:
- Filter: removes solid or liquid aerosols (particles, mists).
- Cartridge or canister: a container holding a filter, sorbent, catalyst or a combination, which removes specific contaminants. Gas and vapor cartridges rely on a sorbent for the chemical they target, and a combination cartridge can also carry a particulate filter.
The practical consequence is that a particulate filter and a vapor cartridge answer different hazards. A search for “respirator cartridges” often mixes the two, which is why the colour code and the filter class are both covered below.
Respirator cartridge colour codes
The California Department of Pesticide Regulation publishes a chart titled “Color Coding for NIOSH Approved Respirator Cartridges and Canisters.” It is a state regulator’s chart rather than a NIOSH document, and its heading tells readers to consult the pesticide label for respirator and cartridge selection. Its colour assignments are:
| Protects against (per CDPR chart) | Colour |
|---|---|
| Organic vapors | Black |
| Ammonia | Bright green |
| Acid gases | White |
| Organic vapors and acid gases | Yellow |
| Organic vapors, ammonia and acid gases | Olive / brown |
| HE / P100 particulate filters | Magenta |
| Organic vapor cartridge with P100 filter | Black + magenta |
| Organic vapor / acid gas with P100 filter | Yellow + magenta |
| Organic vapor / ammonia / acid gas with P100 filter | Olive / brown + magenta |
The pattern to notice is that a combination vapor cartridge carries one colour for the gas or vapor stage and magenta is added when a P100 particulate filter is part of the assembly.
P100 filters and the NIOSH N, R and P classes
NIOSH designates particulate filters by series letter and efficiency: N95, N99, N100, R95, R99, R100, P95, P99 and P100. Federal regulation 42 CFR 84.174 sets the minimum filter efficiency for each level: N100, R100 and P100 filters must reach at least 99.97 percent, the 99 level at least 99 percent, and the 95 level at least 95 percent. A P100 is therefore the highest-efficiency level in the P series and is the filter paired with vapor cartridges in the magenta combinations above.
For how the series letters differ and how N95 and N100 compare, see the N95 vs N100 comparison and the guide to NIOSH-approved N95 masks.
Organic vapor cartridges and change schedules
An organic vapor cartridge is the black-band type in the chart above. OSHA does not leave its replacement to the wearer’s judgment. For gases and vapors, 1910.134(d)(3)(iii) allows an air-purifying respirator only if it has an end-of-service-life indicator (ESLI) certified by NIOSH for the contaminant, or, where no appropriate ESLI exists, the employer implements a change schedule for canisters and cartridges based on objective information or data. The standard defines an ESLI as “a system that warns the respirator user of the approach of the end of adequate respiratory protection.” Cartridges, canisters and filters are also named among the items to be covered when respirators are inspected, in 1910.134(h)(3)(ii)(A).
The colour of a cartridge therefore identifies its type, not its remaining life. For a laboratory’s full program, including how change schedules fit in, see respiratory protection program for the laboratory.
Cartridge types compared with what each does not tell you
| Item | What it tells you | What it does not tell you |
|---|---|---|
| Colour band (CDPR chart) | The contaminant class the cartridge is built for | Whether the respirator is certified for your use, or how long the cartridge lasts |
| Filter designation (for example P100) | Series letter and minimum efficiency under 42 CFR 84.174 | Any protection against gases or vapors |
| NIOSH certification | The respirator is certified, and OSHA requires it be used within the conditions of that certification | That a given cartridge suits a given workplace chemical |
| ESLI | A certified warning of approaching end of protection, for the contaminant it is certified for | Anything for a contaminant it is not certified for; without one, a change schedule is needed |
Where it matters for labs, clinics and supply decisions
For anyone specifying or stocking respirator cartridges, the sourced points are narrow but firm. OSHA requires the employer to select a NIOSH-certified respirator and to use it in compliance with the conditions of its certification (1910.134(d)(1)(ii)). Gas and vapor protection requires either an ESLI or a documented change schedule, so a cartridge listing is not a complete answer on its own. And a particulate filter and a vapor cartridge are not interchangeable: they remove different kinds of contaminant.
Common misunderstandings
- “The colour tells me it is approved.” The colour identifies the contaminant class. Approval is a separate matter: the respirator must be NIOSH-certified and used within its certification.
- “A P100 stops vapors.” P100 is a particulate filter classification. A P100 filter removes aerosols; vapor protection comes from a sorbent cartridge, which is why combination assemblies show two colours.
- “Cartridges last until I smell something.” OSHA’s route for gases and vapors is a NIOSH-certified ESLI or an objective-data change schedule.
- “Any magenta filter is the same.” Magenta marks HE / P100 filters on the CDPR chart, but the N, R and P series carry different designations, and the 95, 99 and 99.97 percent levels are different efficiency levels.
Frequently asked questions
What is a respirator?
Under 1910.134, an air-purifying respirator is a respirator with a filter, cartridge or canister that removes specific air contaminants. Other types, such as atmosphere-supplying respirators, supply air from a separate source; OSHA’s standard allows an atmosphere-supplying respirator as one of the choices for gas and vapor hazards.
How does a respirator work?
An air-purifying respirator passes the air the wearer breathes through a filter, sorbent or catalyst that removes specific contaminants: filters take out aerosols, and sorbent cartridges take out the gases or vapors they are made for.
Is an N95 a respirator?
Yes. N95 is a NIOSH filter designation. NIOSH lists N95 among its approved particulate filtering facepiece respirators, and an N95 may let no more than 5 percent of near-worst-case test particles through. It is a filter, not a vapor cartridge. See what an N95 respirator is.
What is required before using a respirator?
OSHA requires the employer to select a NIOSH-certified respirator and use it within the conditions of its certification. Medical clearance and fit testing are the other program pieces covered on this site; see respirator medical clearance and respirator fit testing requirements.
Sources
- OSHA, 29 CFR 1910.134 Respiratory protection, via eCFR (checked 2026-10-29): ecfr.gov, 29 CFR 1910.134
- 42 CFR 84.174 Respirator filter efficiency levels, via eCFR (checked 2026-10-29): ecfr.gov, 42 CFR 84.174
- NIOSH, NIOSH-Approved Particulate Filtering Facepiece Respirators (checked 2026-10-29): cdc.gov/niosh
- California Department of Pesticide Regulation, Color Coding for NIOSH Approved Respirator Cartridges and Canisters (checked 2026-10-29): cdpr.ca.gov chart (PDF)
