HAZWOPER guide · 2 min read · Updated 2026-11-03
PPE Levels A, B, C and D Explained (EPA and OSHA HAZWOPER)
HAZWOPER sorts chemical protective ensembles into four levels, A through D, described in OSHA 29 CFR 1910.120 Appendix B and in EPA guidance. The level is chosen from the known or suspected hazard, the routes of exposure and how much is known about the chemicals involved.
Level A: highest respiratory, skin and eye protection
Use when: the substance requires the highest level of protection for skin, eyes and lungs. That means high concentrations of vapors, gases or particulates that are toxic through the skin, unknown substances in a confined or poorly ventilated area, or operations with a high chance of splash, immersion or contact with skin-toxic chemicals.
- Positive-pressure, full-facepiece self-contained breathing apparatus (SCBA), or a positive-pressure supplied-air respirator with escape SCBA
- Totally encapsulating, vapor-tight chemical-protective suit
- Inner and outer chemical-resistant gloves
- Chemical-resistant boots with steel toe and shank
- Two-way radio communications; optional cooling unit, hard hat and coveralls under the suit
Level B: highest respiratory, lesser skin protection
Use when: the highest level of respiratory protection is needed but less skin protection, for example oxygen-deficient atmospheres (below 19.5%), IDLH concentrations, or substances that aren't a significant skin hazard. Level B is the minimum level recommended for initial site entry until hazards are identified.
- Positive-pressure, full-facepiece SCBA or supplied-air respirator with escape SCBA
- Hooded chemical-resistant clothing (splash suit, coveralls or one- or two-piece suit). Not vapor-tight
- Inner and outer chemical-resistant gloves and chemical-resistant boots
Level C: air-purifying respirator
Use when: the type and concentration of airborne substances are known, the criteria for using air-purifying respirators are met, and skin contact isn't expected to cause harm. Oxygen must be at least 19.5%, the contaminant must have adequate warning properties or an end-of-service-life indicator, and concentrations must be below IDLH and within the respirator's protection factor.
- Full-face or half-mask air-purifying respirator (APR) with the correct cartridges, or a powered air-purifying respirator (PAPR)
- Hooded chemical-resistant clothing
- Inner and outer chemical-resistant gloves and boots
Level D: work uniform
Use when: the atmosphere contains no known hazard and work rules out splashes, immersion or unexpected inhalation or contact. Level D is for nuisance contamination only and gives no respiratory protection.
- Coveralls
- Safety boots or shoes, safety glasses or chemical splash goggles, hard hat
- Gloves and face shield as needed
Comparison table
| Level | Respiratory | Skin | Typical situation |
|---|---|---|---|
| A | SCBA or SAR with escape | Vapor-tight, fully encapsulating suit | Unknowns, high vapor concentrations, skin-absorbable toxics |
| B | SCBA or SAR with escape | Splash-protective, hooded | Initial entry, O2 < 19.5%, IDLH air, low skin hazard |
| C | Air-purifying respirator | Splash-protective, hooded | Known contaminant, measured concentrations, APR criteria met |
| D | None | Work uniform | No atmospheric hazard, nuisance contamination only |
Changing levels during work
The level isn't fixed for the whole job. Air monitoring results, new information from site characterization, or a change in tasks can raise or lower it. The site safety and health plan should set action levels that trigger an upgrade or withdrawal. Every level also needs a matching decontamination line.
Heat stress and PPE
Higher levels of protection trap body heat. Workers in Level A and B face serious heat stress risk, so the plan should include work-rest cycles, fluids, monitoring of heart rate or body temperature, and cooling vests where needed.
Frequently asked questions
What is the difference between Level A and Level B PPE?
Both use SCBA or supplied air for maximum respiratory protection. Level A adds a totally encapsulating, vapor-tight suit for maximum skin protection. Level B uses non-vapor-tight, splash-protective clothing.
When can Level C be used?
Level C can be used when the airborne contaminants and their concentrations are known, oxygen is at least 19.5%, concentrations are below IDLH, air-purifying respirator criteria are met, and skin contact is not expected to cause harm.
Does Level D include a respirator?
No. Level D is a work uniform with no respiratory protection and is only for situations with no known atmospheric hazard.
This guide summarizes federal OSHA, Cal/OSHA and EPA rules for training purposes. It is not legal advice. Always check the current regulation text and your site safety and health plan.