A space which has limited openings for entry and exit combined with unfavorable natural ventilation such as CAVES, refrigerators, deep tunnels, pipelines, sewers, silos, tanks, vats, mines, deep trenches or pits, vaults, manholes, chimneys, etc.
A space which has limited openings for entry and exit combined with unfavorable natural ventilation such as CAVES, refrigerators, deep tunnels, pipelines, sewers, silos, tanks, vats, mines, deep trenches or pits, vaults, manholes, chimneys, etc.
