In all municipalities of this state maintaining a paid or volunteer fire department, the personnel of which department is actively and exclusively engaged in fire duty, the governing authorities of such municipality may pay out of the general fund of such municipality reasonable hospital and medical expenses for any member of said fire department on account of any occupational disease contracted or for any accident sustained by said member by reason of his service or discharge of his duty in said department. The governing authorities of such city shall be the sole judge as to whether such illness or such injury was contracted or sustained in the line of duty of any such employee, and the reasonableness of said expenses.