Wildfire smoke contains a mixture of hazards: fine particulates (PM₂.₅) and a variety of gases. The primary recommended protection is filtering out the particulates (using at least an N95 or P100 filter). However, wildfires (especially those involving structures or diverse materials, like urban wildfires) can release volatile organic compounds (VOCs) and some inorganic gases. Notably, smoke may contain organic vapors from burning wood, vegetation, plastics, foam, fabrics (e.g., benzene, formaldehyde) as well as potential acid gases or other irritants.
When to use an N95 v. a P100+multigas respirator?
We recommend using a P100+multigas respirator if you are in the burn scar area and/or cleaning soot/ash. If you’re outside the burn scar area and don’t have visible soot/ash, or if the Air Quality Index (AQI) is ‘very unhealthy’ or ‘hazardous’, then we recommend an N95 respirator.
- Particles (Magenta): This part of the filter captures particles and is required.
- Organic Vapor Cartridge (Black): An organic vapor cartridge with a P100 filter is effective for many smoke-related vapors. It absorbs certain organic vapors that cause smoke odors and health effects (like VOCs and semi-volatiles) and, when paired with a particulate filter, also blocks the fine particles. The American Industrial Hygiene Association suggests a half-face respirator with particulate filters and organic vapor cartridges as a minimum if smoke odors/VOCs are strong.
- Organic Vapor + Acid Gas Cartridge (Yellow): This cartridge captures certain organic vapors and acid gases: chlorine, hydrogen chloride, sulfur dioxide, chlorine dioxide, hydrogen sulfide and hydrogen fluoride.
- Multi-Gas Cartridge (Olive): A multi-gas cartridge covers everything an organic vapor cartridge does plus more. It contains additional sorbents to capture acid gases and other inorganic vapors that a regular organic vapor cartridge would miss. In wildfire smoke, a multi-gas (olive) cartridge would provide the same protection against organic compounds and also help protect against gases like chlorine, hydrogen chloride, and sulfur dioxide that could be released when buildings, plastics, or other materials burn. This broader protection can be important in an urban wildfire or house-fire cleanup scenario.
What are the “N” and “P” designations?
The ”N” means that it is Not resistant to oil, and the “P” means that it is resistant to oil/oil Proof. The ‘95’ means it filters 95% of airborne particles, and the ‘100’ means it filters at least 99.97% of particles.
What do the different color cartridges mean in a P100+organic vapor respirator?
An organic vapor cartridge with a P100 filter is effective for many smoke-related vapors. It will adsorb the organic compounds that cause smoke odors and health effects (like VOCs and semi-volatiles) and, when paired with a particulate filter, will also block the fine particles.
The key difference is that a multi-gas cartridge (olive) provides added insurance against less common gases. If you suspect a broader range of chemicals (say, you’re near burned structures, or the smoke has a chemical odor), the multi-gas offers broader protection than the organic vapor cartridge (black) if you want maximum safety margin. However, for the primary wildfire smoke pollutants (soot particles and organic irritants), an organic vapor cartridge is nearly as effective as a multi-gas cartridge – both will significantly reduce those exposures.
Some last things to remember:
The gas cartridges can get saturated so they need to be changed regularly and they also absorb gases when you’re not wearing them, so be sure to check with the manufacturers’ recommendations on these two items (see ‘Additional Resources’). Last, ensure the respirator fits well. You should do a ‘user seal check’ each time you put it on.
Source: Fitting instructions for respirators
Disclaimers
- Please note that wearing a respirator can make it harder to breathe. Those with medical conditions, including heart or lung conditions, should consult their doctor before wearing a respirator or mask.
- Additionally, masks and respirators are only effective when they are sealed and fit appropriately. Certain facial hair styles may interfere with the seal.
- Masks and respirators should be maintained and replaced per the manufacturer’s instructions.
ADDITIONAL INFORMATION AND RESOURCES
–Cartridge and filter selection guide
–Respirator selection guide with detailed chemical hazard information
–Technical bulletin: Cartridge Change Schedules for Low Exposure Environments
–3 Ways to Reduce Risk from Wildfire Smoke at Home – Healthy Buildings