Related by context. Frequent words. (Click for all words.) 55 stairwells 46 passageways 45 claustrophobic 45 harsh environments 44 stairways 44 ventilated 44 ductwork 44 ventilation 43 claustrophobia 41 flammable materials 41 protective clothing 41 crevices 40 elevators 40 staircases 40 compressed air 40 chimneys 39 duct 39 air ducts 39 ventilate 39 carbon monoxide 39 doorways 38 elevator 38 flue 38 vents 38 ventilating 38 ledges 38 respirators 38 tunnels 38 NIOSH 38 crevice 38 environments 37 egress 37 toxic fumes 37 flammable 37 indoors 37 ladders 37 breathing apparatus 37 outdoors 37 ducts 36 cramped quarters 36 attics 36 combustible materials 36 hazardous 36 rough terrain 36 chutes 35 enclosed 35 cramped 35 Ventilation 35 toxic gases 35 protective gear 35 handrails 35 vapors 35 workplaces 35 stressful situations 35 asbestos fibers 35 cavity 35 forklifts 34 mine shafts 34 crevasses 34 hazardous material 34 physical exertion 34 compartments 34 situations 34 shafts 34 handrail 34 jobsite 33 entryways 33 stairwell 33 decontamination 33 nozzles 33 shaft 33 conveyors 33 upper floors 33 spaces 33 passenger compartment 33 elevator shaft 33 fire extinguisher 33 fire extinguishers 33 slats 33 hazards 33 extinguishers 33 hallways 33 vapor 33 unheated 33 windowless 33 underground tunnels 32 loud noises 32 suction 32 hoses 32 fumes 32 workplace 32 pressurized 32 combustion 32 attic 32 surfaces 32 furnaces 32 nozzle 32 soundproof 32 housings 32 galley 32 scaffolds