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(a) A mine shall be deemed gassy, and thereafter operated as a gassy mine, if:
(1) (21-1b) Flammable gas emanating from the orebody or the strata surrounding the orebody has been ignited in the mine; or
(2) (21-1c) A concentration of 0.25 percent or more, by air analysis, of flammable gas emanating only from the orebody or the strata surrounding the orebody has been detected not less than 12 inches from the back, face, or ribs in any open workings; or
(3) (21-1d) The mine is connected to a gassy mine; or
(4) (21-1a) The Division may designate any mine as gassy if history or past experience indicates that flammable gas in hazardous concentrations is likely to be encountered in such mine.