Cal. Health & Safety Code § 17920.10

(a) Any building or portion thereof including any dwelling unit, guestroom, or suite of rooms, or portion thereof, or the premises on which it is located, is deemed to be in violation of this part as to any portion that contains lead hazards. For purposes of this part, “lead hazards” means deteriorated lead-based paint, lead-contaminated dust, lead-contaminated soil, or disturbing lead-based paint without containment, if one or more of these hazards are present in one or more locations in amounts that are equal to or exceed the amounts of lead established for these terms in Chapter 8 (commencing with Section 35001) of Division 1 of Title 17 of the California Code of Regulations or by this section and that are likely to endanger the health of the public or the occupants thereof as a result of their proximity to the public or the occupants thereof.
(b) In the absence of new regulations adopted by the State Department of Health Services in accordance with the rulemaking provisions of the Administrative Procedure Act (Chapter 3.5 (commencing with Section 11340) of Part 1 of Division 3 of Title 2 of the Government Code) further interpreting or clarifying the terms “deteriorated lead-based paint,” “lead-based paint,” “lead-contaminated dust,” “containment,” or “lead-contaminated soil,” regulations in Chapter 8 (commencing with Section 35001) of Division 1 of Title 17 of the California Code of Regulations adopted by the State Department of Health Services pursuant to Sections 105250 and 124150 shall interpret or clarify these terms. If the State Department of Health Services adopts new regulations defining these terms, the new regulations shall supersede the prior regulations for the purposes of this part.
(c) In the absence of new regulations adopted by the State Department of Health Services in accordance with the rulemaking provisions of the Administrative Procedure Act defining the term “disturbing lead-based paint without containment” or modifying the term “deteriorated lead-based paint,” for purposes of this part “disturbing lead-based paint without containment” and “deteriorated lead-based paint” shall be considered lead hazards as described in subdivision (a) only if the aggregate affected area is equal to or in excess of one of the following:
1. (1) Two square feet in any one interior room or space.
2. (2) Twenty square feet on exterior surfaces.
3. (3) Ten percent of the surface area on the interior or exterior type of component with a small surface area. Examples include window sills, baseboards, and trim.
(d) Notwithstanding subdivision (c), “disturbing lead-based paint without containment” and “deteriorated lead-based paint” shall be considered lead hazards, for purposes of this part, if it is determined that an area smaller than those specified in subdivision (c) is associated with a person with a blood lead level equal to or greater than 10 micrograms per deciliter.
(e) If the State Department of Health Services adopts regulations defining or redefining the terms “deteriorated lead-based paint,” “lead-contaminated dust,” “lead-contaminated soil,” “disturbing lead-based paint without containment,” “containment,” or “lead-based paint,” the effective date of the new regulations shall be deferred for a minimum of three months after their approval by the Office of Administrative Law and the regulations shall take effect on the next July 1 or January 1 following that three-month period. Until the new definitions apply, the prior definition shall apply.