Diseases of firefighters suffered in line of duty; presumption.

For any municipality, special fire control district, chapter plan, local law municipality, local law special fire control district, or local law plan under this chapter, any condition or impairment of health of a firefighter caused by tuberculosis, hypertension, or heart disease resulting in total or partial disability or death shall be presumed to have been accidental and suffered in the line of duty unless the contrary is shown by competent evidence, provided that such firefighter shall have successfully passed a physical examination before entering into such service, which examination failed to reveal any evidence of such condition. This section shall be applicable to all firefighters only with reference to pension and retirement benefits under this chapter.