Related by context. Frequent words. (Click for all words.) 54 ventilation 53 passageways 52 ventilation ducts 50 plumbing pipes 50 vents 49 ventilation shafts 49 electrical conduits 48 chimney flue 48 shutoff valve 48 ducts 47 ductwork 47 firebox 47 penstock 47 combustible gases 46 tunnels dug 46 elevator shafts 46 exhaust vents 46 dryer vents 46 poisonous carbon monoxide 46 louvres 46 passageway 46 flues 46 crawlspaces 46 acetylene torch 46 tunnels 46 heating ducts 46 conveyer belts 46 duct 45 vertical shafts 45 broken standpipe 45 shafts 45 narrow passageway 45 stairwells 45 longwall mining machine 45 exhaust vent 45 Poorly maintained 44 ceiling joists 44 shaft 44 louvers 44 pneumatic drills 44 ventilation shaft 44 rockface 44 wiring plumbing 44 noxious gases 44 reinforcing rods 44 gratings 44 drainpipes 44 air conditioning ducts 44 hollow tubes 43 potassium ions 43 stairways 43 flammable gases 43 pinholes 43 faulty heater 43 inert gases 43 electrical arcing 43 depressurize 43 ducting 43 airlocks 43 corroded pipes 43 air conditioning vents 43 lava tubes 42 Trapped miners 42 Ventilation 42 infrared beams 42 Compressed air 42 chimney 42 tubes 42 toxic gases 42 spalling 42 compressed air 42 combustion gases 42 operable windows 42 #/#-in [001] 42 vapor barrier 42 mine shafts 42 chimney stacks 42 Manhole covers 42 MSHA 42 louver 42 drafty windows 42 superheated steam 42 reactor coolant 42 hydraulic jack 41 poisonous gases 41 solder joints 41 alveoli 41 miners 41 metal grates 41 silt fences 41 valves 41 Lethal gases 41 doorframes 41 detectors 41 chimneys 41 confined spaces 41 furnace 41 venetian blinds 41 properly ventilated 41 obstructions 41 ventilations