Mass. Gen. Laws ch. 32 § 94A
Notwithstanding the provisions of any general or special law to the contrary affecting the non-contributory or contributory retirement system, any condition of impairment of health caused by any disease of the lungs or respiratory tract, resulting in total disability or death to a uniformed member of a paid fire department, including, without limitation, any permanent crash crewman, crash boatman, fire controlman or assistant fire controlman employed at the General Edward Lawrence Logan International Airport, members of the 104th fighter wing fire department, members of the Devens fire department established pursuant to chapter 498 of the acts of 1993 or members of the Massachusetts military reservation fire department, shall, if he successfully passed a physical examination on entry into such service or subsequent to such entry, which examination failed to reveal any evidence of such condition, be presumed to have been suffered in the line of duty, as a result of the inhalation of noxious fumes or poisonous gases, unless the contrary be shown by competent evidence.
Mass. Gen. Laws ch. 32, § 94A