Kev tawg tshwm sim hauv qee thaj tsam, tshwj xeeb hauv cov kev txwv tawg.
Cov txwv tawg rau CH4 hauv huab cua ntau los ntawm 5% rau 15% methane concentration. Kev tawg yuav tshwm sim yog tias qhov methane qhov ntim ntawm qhov sib npaug poob hauv qhov no 5% rau 15% ntau yam thiab los rau hauv kev sib cuag nrog ib tug qhib nplaim taws.