Respirator Filters: N95, P100 & Cartridge Colors
A respirator is only as good as what’s on it. Particle filters catch dust, mist and fumes. Chemical cartridges absorb gases and vapors. Using the wrong one, or using it too long, means you’re breathing the hazard.
- Construction
- General Industry
- Painters
Particle filters: the letter and the number
| Letter | Meaning | Use with oil mist? |
|---|---|---|
| N | Not resistant to oil | No |
| R | Resistant to oil | Yes, generally for up to one 8-hour shift |
| P | Oil-proof | Yes, follow the maker’s time limit |
The number is how much of the test particles the filter caught: 95 (95%), 99 (99%) or 100 (99.97%). So an N95 filters 95% and isn’t for oil; a P100 filters 99.97% and is oil-proof. P100 filters are usually magenta, and are common for silica, lead, asbestos and welding fume.
Particle filters don’t stop gases or vapors. A dust mask won’t protect you from paint solvent fumes.
Chemical cartridge colors
Colors follow a common U.S. code, but always read the label on the cartridge too.
| Color | Protects against |
|---|---|
| Black | Organic vapors (many solvents, paints, adhesives) |
| White | Acid gases (like chlorine or hydrogen chloride) |
| Yellow | Organic vapors and acid gases |
| Green | Ammonia and methylamine |
| Olive | Multi-gas or multi-contaminant |
| Magenta | P100 particle filter |
Combination cartridges, like organic vapor plus P100, protect against both a vapor and particles, such as spray painting.
When to change them
- Particle filters: when breathing gets harder, or the filter is damaged, wet or dirty. Disposable N95s should be thrown away when damaged, soiled or hard to breathe through.
- Gas and vapor cartridges: on a change schedule your employer sets from the maker’s data or testing, or when an end-of-service-life indicator shows. OSHA requires this.
- Don’t wait to smell it. Many chemicals can’t be smelled until you’re already overexposed, and some dull your sense of smell.
- Store cartridges in a sealed bag between uses; open cartridges keep absorbing from the air.
No filter supplies oxygen. Filters and cartridges are useless in oxygen-deficient air, and many chemicals have no approved cartridge. Those jobs need supplied air or SCBA. See Confined Spaces.
Is it really approved?
- The respirator or its packaging has a NIOSH approval number (it starts with “TC-”)
- “NIOSH” is spelled correctly, and the maker’s name is on it
- Filters and cartridges are the same brand as the facepiece; mixing brands voids the approval
- The approval can be found on NIOSH’s Certified Equipment List
- Surgical masks and cloth masks are not respirators
Standards & references
- 29 CFR 1910.134: Respiratory protection (change schedules: 1910.134(d)(3)(iii))
- NIOSH National Personal Protective Technology Laboratory
- See also: Respiratory Protection · PAPRs · Solvents
Last updated: