Air-purifying respirator cartridges are color-coded by the contaminant they protect against (NIOSH / 42 CFR 84). Pick your hazard below to see the correct cartridge color, the particulate filter class to pair with it, and the respirator type you need for the protection factor — then verify against your SDS and exposure assessment.
NIOSH cartridge color codes
| Color | Protects against |
|---|---|
| Black | Organic vapors |
| White | Acid gases |
| Yellow | Organic vapors + acid gases |
| Green | Ammonia & methylamine |
| Blue | Carbon monoxide |
| Orange | Mercury vapor / chlorine |
| Olive | Multi-gas / multiple contaminants |
| Magenta | Particulates (P100 / HEPA) |
Particulate filter classes (42 CFR 84)
| Series | Oil resistance | 95 / 99 / 100 |
|---|---|---|
| N (N95, N99, N100) | Not oil-resistant | Efficiency: 95% · 99% · 99.97% (100) |
| R (R95, R99, R100) | Oil-resistant (one shift) | |
| P (P95, P99, P100) | Oil-proof |
Assigned Protection Factors (OSHA 1910.134)
| Respirator | APF | Max use (× the PEL) |
|---|---|---|
| Filtering facepiece / elastomeric half-mask | 10 | 10× |
| Full-facepiece air-purifying | 50 | 50× |
| PAPR, loose-fitting hood/helmet | 25 | 25× |
| PAPR, tight-fitting full facepiece | 1,000 | 1,000× |
If the contaminant concentration exceeds (APF × exposure limit), you must step up to a higher-APF respirator. Half-mask and full-face respirators accept the cartridges above.
Frequently asked questions
Do P100 filters attach directly or need a retainer?
It depends on the model. Some P100 filters (e.g. 3M 2091/2097) snap directly onto the cartridge bayonet, while thin pancake pre-filters need a retainer. Always confirm the manufacturer’s pairing — see our cartridges & filters.
When do I change my cartridges?
OSHA requires a change-out schedule based on a manufacturer’s software estimate or objective data — not on smell. Gas/vapor cartridges have no end-of-service-life indicator unless stated. Replace particulate filters when breathing resistance increases.
Can one cartridge cover multiple hazards?
Yes — combination cartridges (e.g. OV/AG, multi-gas, or gas + P100) exist for mixed exposures. Match every component of your exposure; an organic-vapor cartridge will not stop particulates and vice-versa.
What does N vs R vs P mean?
It is oil resistance: Not resistant, Resistant (one shift), oil-Proof. Use R or P where oil aerosols are present (machining, some paints).
Shop respirators & cartridges
Educational reference only. Cartridge selection must be based on a workplace hazard assessment, the chemical’s Safety Data Sheet, measured concentrations, and a change-out schedule under OSHA 29 CFR 1910.134. Not valid for IDLH, oxygen-deficient, or unknown atmospheres. Color codes per NIOSH / 42 CFR 84.
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Built and reviewed by the WC Safety editorial team (Steven Eaton). We curate and review industrial PPE against ANSI, NIOSH and OSHA standards.