Notwithstanding the provisions of any general or special law or to any state or municipal retirement system, any city or town may, by ordinance, provide that every condition of impairment of health caused by smoke inhalation of the lungs or respiratory tract, resulting in total disability or death to a uniformed member of a paid fire department, is 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 is shown by competent evidence; provided, that the person benefiting by the presumption passes a physical examination upon entry into service or subsequent to entry an examination failed to reveal any evidence of the condition.