By July 31, 1971, the *retirement board shall adopt minimum medical and health standards for membership coverage into the Washington law enforcement officers' and firefighters' retirement system act. In adopting such standards the *retirement board shall consider existing standards recommended by the international association of chiefs of police and the international association of firefighters, and shall adopt equal or higher standards, together with appropriate standards and procedures to insure uniform compliance with this chapter. The standards when adopted shall be published and distributed to each employer, and each employer shall adopt certification procedures and such other procedures as are required to insure that no law enforcement officer or firefighter receives membership coverage unless and until he or she has actually met minimum medical and health standards: PROVIDED, That an elected sheriff or an appointed chief of police, fire chief, or director of public safety shall not be required to meet the age standard. The *retirement board may amend the minimum medical and health standards as experience indicates, even if the standards as so amended are lower or less rigid than those recommended by the international associations mentioned above. The cost of the medical examination contemplated by this section is to be paid by the employer.