| MSHA's Accident Prevention Program
Hazards with a Falling Barometer
A falling barometer is an indication of falling atmospheric pressure. The affect of falling atmospheric pressure is significant to a coal mine environment. Methane from the coal seam is liberated into the mine atmosphere at a greater rate and may also appear in areas of the mine not normally prone to methane accumulations. Seals will begin to "out-gas" at a greater rate. Explosive methane/air mixtures may be present in the area of the seals. The atmospheres from gob areas containing methane and low oxygen concentrations will migrate toward the active areas of the mine. Also see information in a similar safety idea titled Hazards with a Rising Barometer.