California Code, Health and Safety Code - HSC § 26140

(a) Subject to subdivisions (b), (c), and (d), a seller or transferor of commercial or industrial real property shall provide written disclosure to prospective buyers as soon as practicable before the transfer of title when the seller or transferor knows of the presence of mold, both visible and invisible or hidden, that affects the unit or building and the mold either exceeds permissible exposure limits to molds established by subdivisions (a), (b), and (c) of Section 26103 or poses a health threat, according to the department's guidelines as developed pursuant to Section 26105.

(b) A seller or transferor of commercial or industrial real property shall be exempt from providing written disclosure pursuant to this subdivision if the presence of mold was remediated according to the mold remediation guidelines developed by the department pursuant to Section 26130.

(c) A commercial or industrial real property seller shall not be required to conduct air or surface tests of units or buildings to determine whether the presence of molds exceeds the permissible exposure limits to molds established by subdivisions (a) and (b) of Section 26103.

(d) The requirements of this section shall not apply until the first January 1 or July 1 that occurs at least six months after the department adopts standards pursuant to Sections 26103 and 26105 and develops guidelines pursuant to Section 26130.