§ 363-ff. Firefighter certain impairments of health; presumption. Notwithstanding any other provisions of this chapter to the contrary, any condition of impairment of health caused by Parkinson's Disease, resulting in total or partial disability or death to a paid firefighter, who successfully passed a physical examination on entry into firefighter service, which examination failed to reveal any evidence of such condition, shall be presumptive evidence that, unless the contrary be proven by competent evidence, such disability or death (a) was caused by the natural and proximate result of an accident, not caused by such firefighter's own willful negligence, and (b) was sustained in the performance and discharge of duty.