California Code, Public Resources Code - PRC § 5163

(a) No person shall initially be employed in connection with a park, playground, recreational center, or beach used for recreational purposes by a city or county in a position requiring contact with children, or as a food concessionaire or other licensed concessionaire in that area, unless the person produces or has on file with the city or county a certificate showing that within the last two years the person has been examined and has been found to be free of communicable tuberculosis.

(b) Thereafter, those employees who are skin test negative shall be required to undergo the foregoing examination at least once each four years for so long as the employee remains skin test negative.  Once an employee has a documented positive skin test which has been followed by an X-ray, the foregoing examination is no longer required and a referral shall be made within 30 days of the examination to the local health officer to determine the need for followup care.

“Certificate” means a document signed by the examining physician and surgeon who is licensed under Chapter 5 (commencing with Section 2000) of Division 2 of the Business and Professions Code, or a notice from a public health agency or unit of the tuberculosis association which indicates freedom from active tuberculosis.