Respirators are critical personal protective equipment (PPE). But they are definitely not all the same.
Selecting the wrong respirator type can leave workers unprotected against serious respiratory hazards.
This guide explains the key differences between respirator categories to help you choose the right protection.
Two Main Classes of Respirators
All respirators fall into one of two categories: air-purifying or atmosphere-supplying.
Air-Purifying Respirators (APRs)
APRs filter contaminants from the ambient air you breathe.
They only work when there is sufficient oxygen (at least 19.5%).
Contaminant levels must be below immediately dangerous to life or health (IDLH) concentrations.
Types of air-purifying respirators include:
- Filtering Facepiece Respirators (FFRs) — disposable masks like N95, N99, P100
- Elastomeric Half-Face Respirators — reusable with replaceable cartridges
- Elastomeric Full-Face Respirators — higher protection, includes eye protection
- Powered Air-Purifying Respirators (PAPRs) — battery-powered filtered air supply
Atmosphere-Supplying Respirators
These respirators provide clean air from an independent source.
They are required for oxygen-deficient environments, IDLH conditions, or unknown contaminant concentrations.
Types include:
- Supplied-Air Respirators (SARs) — air line connected to remote source
- Self-Contained Breathing Apparatus (SCBA) — portable air tank, like firefighters use
- Combination units — SAR with escape SCBA bottle
NIOSH Filter Classifications
NIOSH certifies particulate filters using a letter-number system.
The Letter: Oil Resistance
- N (Not oil-resistant) — use only for non-oil particles
- R (oil-Resistant) — limited oil exposure, single shift only
- P (oil-Proof) — extended use in oil-containing atmospheres
The Number: Filtration Efficiency
- 95 — filters at least 95% of airborne particles
- 99 — filters at least 99% of airborne particles
- 100 — filters at least 99.97% of particles (HEPA equivalent)
Example: P100 means oil-proof with 99.97% filtration.
P100 is required for lead, asbestos, and many toxic dusts.
Gas and Vapor Cartridges
Chemical cartridges are color-coded by hazard type:
- Black — organic vapors (solvents, paints)
- White — acid gases (chlorine, hydrogen chloride)
- Yellow — organic vapors + acid gases combined
- Green — ammonia
- Olive — multi-gas/vapor
- Purple — HEPA/P100 particulate
Always verify the cartridge matches your specific contaminant.
Assigned Protection Factors (APF)
OSHA assigns protection factors indicating how much the respirator reduces exposure.
Higher APF means greater protection:
- APF 10 — half-face APRs, disposable N95s (exposure reduced to 1/10)
- APF 25 — PAPRs with loose-fitting hood
- APF 50 — full-face APRs, PAPRs with tight-fitting facepiece
- APF 1000 — SAR with full facepiece
- APF 10,000 — SCBA with full facepiece (pressure-demand)
Select a respirator with an APF that keeps exposure below the occupational exposure limit.
How to Choose the Right Respirator
Step 1: Identify the Hazard
What contaminants are present? Particles, gases, vapors, or a combination?
What are the exposure levels?
Is the atmosphere oxygen-deficient or IDLH?
Step 2: Calculate Required Protection
Divide workplace concentration by the occupational exposure limit (OEL).
This gives you the minimum required APF.
Choose a respirator type that meets or exceeds this APF.
Step 3: Consider Practical Factors
- Duration of use — comfort matters for extended wear
- Communication needs — some designs allow easier speech
- Facial hair — PAPRs or loose-fitting designs may be needed
- Glasses — full-face designs need prescription inserts
- Heat stress — PAPRs reduce breathing resistance
Common Applications by Respirator Type
N95 Disposable
Best for: construction dust, drywall sanding, healthcare airborne precautions, wildfire smoke, general nuisance dust.
Half-Face with Cartridges
Best for: paint spraying, pesticide application, solvent work, welding fumes.
Full-Face Respirator
Best for: asbestos abatement, lead paint removal, chemical handling with splash hazard, silica exposure.
PAPR
Best for: healthcare isolation, pharmaceutical manufacturing, workers who cannot fit-test, extended high-hazard work.
Supplied-Air / SCBA
Best for: confined space entry, emergency response, sandblasting, chemical spill cleanup.
OSHA Requirements
When respirators are required, OSHA 29 CFR 1910.134 mandates:
- Written respiratory protection program
- Medical evaluation before fit testing
- Annual fit testing for tight-fitting respirators
- Training on use, limitations, and maintenance
- Proper storage and maintenance procedures
Key Takeaways
- Respirators vary enormously — one type does not fit all hazards
- Match the respirator APF to your calculated exposure
- Air-purifying respirators require adequate oxygen and sub-IDLH levels
- Chemical cartridges are contaminant-specific
- Fit testing is mandatory for tight-fitting respirators
Next Steps
Browse our Respiratory Protection category for NIOSH-certified respirators.
We carry everything from N95 disposables to full-face and PAPR systems.
Need help selecting the right respirator? Use our AI Sourcing Assistant or request a quote.