Gas mask

A wearable respiratory protective device that filters contaminated air or supplies breathable air, shielding the wearer from hazardous gases, vapors, particles, or biological agents.

Air-purifying respirator: A respirator that removes contaminants from ambient air before the wearer inhales it. Gas masks are air-purifying respirators when they clean surrounding air rather than supply it.
John Stenhouse: A Scottish chemist who developed an early charcoal-based respirator in the nineteenth century. His charcoal respirator anticipated the sorbent principle used in later protective masks.
Chemical warfare agent: A toxic chemical used to injure, incapacitate, or kill people through its physiological effects. Military masks are designed around specific agents and their routes of exposure.
Powered air-purifying respirator: A respirator that uses a battery-powered blower to move filtered ambient air to a facepiece or hood. It filters surrounding air like a mask but reduces breathing resistance with powered airflow.
Canister respirator: A respirator that passes inhaled air through a replaceable canister containing contaminant-removal media. Its canister holds the chemical sorbents and filters that give many gas masks their protection.
Garrett Morgan: An American inventor whose safety hood supplied filtered air to firefighters and rescuers. His 1914 safety hood demonstrated a practical wearable device for hazardous atmospheres.
Biological warfare: The deliberate use of pathogens or toxins to harm people, animals, or crops. Particle-filtering masks can reduce inhalation of biological aerosols, though protection depends on fit.
Supplied-air respirator: A respirator that delivers breathable air from a source outside the wearer’s immediate environment. It avoids reliance on contaminated ambient air, unlike a filtering gas mask.
Activated carbon: A porous form of carbon used to adsorb many gases and vapors. Its extensive internal surface captures many vapor molecules in gas-mask canisters.
World War I gas mask: A family of military respirators developed to protect troops from chemical warfare during World War I. The widespread use of chemical weapons accelerated mask design and mass production.

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