Respirators in Fire Safety: Types, Fit Testing and Limits

Fire smoke is not just dirty air. It carries toxic gases such as carbon monoxide, fine soot and chemicals from burning plastics and furniture, and it can be short of oxygen. The only respirator that protects a firefighter in smoke is positive-pressure self-contained breathing apparatus (SCBA), the BA set with its own cylinder of air. Everything else on this page has its place, but not inside a burning building.

What you are breathing at a fire

Toxic gases, fine particles and chemicals, in air that may not have enough oxygen. A filter mask cannot add oxygen and does not stop carbon monoxide. That is why firefighters in smoke wear positive-pressure SCBA, and why nobody should go into smoke with an N95, a dust mask or a gas mask.

Two families of respirators

• Air-purifying respirators (APR) clean the air around you with a filter or cartridge. They include disposable filtering masks, and half or full-face masks with cartridges. They work only where there is enough oxygen and the contaminant is known.
• Supplied-air respirators (SAR) give you clean air from an outside source, either an airline or a cylinder. SCBA, where you carry the cylinder on your back, gives the same kind of protection without a hose.

Which one you need depends on the hazard: dust, a known gas, smoke, or air that nobody has tested.

How filters work, and what they miss

Particle filters trap dust, soot and mist mechanically. Gas and vapour cartridges soak up particular chemicals, and combination filters do both. Each cartridge works only for the gases it is made for, so read the label.

N95 is an American rating for masks that filter at least 95% of airborne particles. In India, filtering half masks are made to BIS IS 9473, which grades them FFP1, FFP2 and FFP3. All of these filter particles only. They do not stop gases or vapours, and they do not supply oxygen.

Fit testing and seal checks

A respirator that does not seal on your face lets dirty air leak in around the edge. A fit test checks the seal on your face, using the exact model you will wear. A seal check is the quick test you do yourself every time you put the mask on. Beards, stubble and spectacle arms can break the seal.

Heat and comfort

Responders wear respirators while working hard in the heat. Adjustable straps, light materials and good valves make a mask bearable for longer, and a mask people can bear is a mask they keep on. Do not take the facepiece off during overhaul just because the flames are out. Smouldering debris still gives off gas.

Respirators for particular hazards

Crews fighting forest and grass fires in the open face heavy smoke particles, and sometimes use masks with high-efficiency particle filters such as P100, another American rating. These still do not remove carbon monoxide or other gases. Match the respirator to the hazard, and when in doubt, use SCBA.

Maintenance and storage

• Inspect facepieces, straps and valves after every use.
• Clean reusable masks as the maker says.
• Change filters and cartridges on the maker’s schedule, and sooner if breathing gets harder or you can smell the contaminant.
• Store masks in a clean, dry place, away from dust, sunlight and chemicals.
• Check SCBA cylinder pressure and the low-air alarm before every shift.

Training

Everyone who wears a respirator should be trained to put it on and take it off properly, do a seal check, know what their mask does not protect against and know when to leave. Practise with SCBA in drills, so your hands know the drill before you need it for real.

If someone is overcome by smoke

If you are not on SCBA, get out of smoke at once and stay low. If your low-air alarm sounds, leave with your partner straight away. Get anyone overcome by smoke into fresh air and call 108 or 112. Dizziness, headache, nausea or confusion after breathing smoke needs medical attention, even if the person seems to recover.

Before your next shift, find out what your team’s respirators actually stop, check the filter dates, and do a seal check on your own mask.