They are included in preparedness kits , after the September 11 attacks . Preparedness lists , such as those presented by Ready.Gov , often recommend smoke hoods , although some lists use alternate names such as " fume hoods , " " respirator hoods , " or " self-rescue hoods . " As most modern construction contains materials that produce toxic smoke or fumes when burned , smoke hoods can allow people to make a safe escape from buildings when it might not otherwise be possible . Smoke hoods present on aircraft , also called protective breathing equipment ( or PBEs ) , typically generate oxygen for anywhere from 30 seconds to 15 minutes . The oxygen is kept in a closed circuit , usually thanks to a tight neck seal . A scrubber system may be present to reduce the levels of carbon dioxide , and is breathable for around 20 minutes . When the oxygen supply ends , the hood will begin deflating and must be removed to avoid suffocation . These devices represent a subgroup of smoke hoods called '' positive-pressure respirators '' , which prevent the ingress of smoke or toxic gases by maintaining a higher air pressure inside the mask than outside . Consequently , any leak will cause fresh air to leak out of the mask , rather than toxic air to leak in
September 11 attacks
September 11 attacks
Smoke hood