On October 9, 2015, California Governor Brown signed Senate Bill 655 which adds visible mold growth to the list of dangerous health conditions which define substandard housing in the state’s Health and Safety Code.(Cal. Health & Safety Code §17920.3). The bill was introduced by Senator Holly Mitchell, D-Los Angeles.

As of January 1, 2016, mold is now officially a condition under California law that makes a home substandard. The owner of a rental property cited as by a local (city or county) code inspector substandard is required to repair the substandard condition.

According to the bill’s author:

“mold is not explicitly referenced in state code, causing local enforcement agencies to be uncertain about their authority to address this common complaint. This uncertainty leads to widely inconsistent enforcement approaches to mold across the state, ranging from taking no enforcement action to limiting enforcement to water-related issues that are identified in the code to, in a few places, enforcing mold issues as a general nuisance.

“Because of the growing evidence linking mold to adverse health impacts, state code needs to be updated to provide local enforcement agencies with clear authority to address mold complaints. This authority should include the ability to require both the cleaning or removal of moldy materials and the remediation of underlying sources of moisture. Current state code provides local enforcement agencies with the authority to address moisture issues. SB 655 would add mold as a substandard condition in Health and Safety Code 17920.3.”

California Health and Safety Code § 17920.3: Establishes minimum standards for residential rental properties. Includes ‘‘dampness of habitable rooms’’ as a substandard condition to the extent that it ‘‘endangers the life, limb, health, property, safety, or welfare of the public or the occupants.’’ Part of state housing code, which provides for local enforcement.

Visible mold growth, as determined by a health officer or a code enforcement officer, as defined in Section 829.5 of the Penal Code, excluding the presence of mold that is minor and found on surfaces that can accumulate moisture as part of their properly functioning and intended use.

The California Department of Consumer Affairs had said,

“… the presence of mold conditions in the rental unit that affect the livability of the unit or the health and safety of tenants” may be a way in which the implied habitability of a unit is violated and that a tenant may be able to claim a breach of the implied warranty on the basis of documented contamination.

The law specifies that visible mold growth, excepting mold that is minor and found on surfaces that can accumulate moisture as part of their proper and intended use, is a type of inadequate sanitation and therefore a substandard condition. Under the law, mold is classified as microscopic organisms or fungi that can grow in damp conditions in the interior of a building. By expanding the definition of a crime, this bill would impose a state-mandated local program.

The bill provides local enforcement agencies with clear authority to address mold complaints and to require the cleaning and removal of moldy materials and the remediation of moisture intrusion problems. It will also mean that code enforcement officers need expertise in mold assessment and remediation.

The California Department of Public Health (CDPH) had stated in its “Statement on Building Dampness, Mold, and Health” (updated 2016):

“CDPH has concluded that the presence of water damage, dampness, visible mold, or mold odor in schools, workplaces, residences, and other indoor environments is unhealthy. We recommend against measuring indoor microorganisms or using the presence of specific microorganisms to determine the level of health hazard or the need for urgent remediation.

Rather, we strongly recommend addressing water damage, dampness, visible mold, and mold odor by (a) identification and correction of the source of water that may allow microbial growth or contribute to other problems, (b) the rapid drying or removal of damp materials, and (c) the cleaning or removal of mold and moldy materials, as rapidly and safely as possible, to protect the health and well-being of building occupants, especially children.”

CDPH’s position is based on the current consensus among scientists and medical experts (cited in the Statement) that:

  • Visible water damage, damp materials, visible mold, and mold odor indicate an increased risk of respiratory disease.
  • The traditional methods used to measure mold exposure do not reliably predict health risks.
  • The differentiation of some molds as “toxic molds” that are especially hazardous to healthy individuals is not justified by available evidence.
  • The most important steps in dealing with indoor dampness or mold are to identify the source of moisture and take the necessary steps to make repairs to stop them, dry or remove damp materials, and clean or remove moldy materials.

Here is an excerpt of analysis from the CA Assembly website prior to the bill being signed as law:

Arguments in support: Supporters of this bill contend that mold is a common complaint of California tenants. The California Association of Code Enforcement Officers, a co-sponsor of this bill, notes that under existing law code enforcements’ authority over mold and moldy materials is “murky at best.” The bill’s other co-sponsor, Regional Asthma Management and Prevention (RAMP), points to the significant health impacts associated with mold, and notes that a 2007 study estimates that 21% of the nation’s asthma cases are attributable to dampness and mold in the home. Supporters also cite a 2014 report indicating that 12.2% of Californians experience excessive moisture in their homes, with renters in low-income communities and communities of color disproportionately impacted by unwanted dampness in their homes.

Arguments in opposition: Opponents primarily represent statewide and regional associations of apartment owners and homeowners associations. Opponents question the need for this bill, and contend that existing law relating to substandard housing and habitability already allows tenants to bring claims against their landlords when unhealthy living conditions relating to mold exist.

They contend that mold as a substandard condition will lead to abusive litigation practices, and tenants will have the right to sue for substandard housing conditions when any mold is present, including mold that is not harmful. Opponents also point to the lack of a consensus within the scientific and medical communities regarding which molds pose serious health risks, and argue that this bill does not present a workable standard for code enforcement or for property owners who want to stay in compliance with the law.


In 2001, the Toxic Mold Protection Act (Senate Bill 732, Ortiz*) mandated that the California Department of Health Services (currently the California Department of Public Health, (CDPH) determine the feasibility of setting Permissible Exposure Limits (PELs) for mold in indoor environments.

The 2001 Toxic Mold Protection Act (SB 732, Ortiz) directed the California Department of Health Services (now California Department of Public Health or CDPH) to determine the feasibility of establishing health-based permissible exposure limits (PELS) for indoor mold. If that were possible, the CDPH was also directed to create programs to develop guidelines for mold assessment, clean-up, and disclosure in residences.

However, the CDPH responded in 2005 (“Report to the California Legislature on Implementation of the Toxic Mold Protection Act of 2001“) that available evidence did not support the establishment of science-based PELs for indoor molds at that time. This view was reaffirmed in the Department’s July 2008 update. To date, as of 2015, the evidence on this question has not changed the CDPH position.

The CDPH also said in 2005, that it “agrees with other building and health professionals that indoor dampness, water intrusion, or fungal growth should always be eliminated in a safe and efficient manner.” This advice was expanded in CDPH Statement on Indoor Dampness and Mold (2011), based on the increased availability scientific information.

Here are some other mold laws on the books in California:

2001 Bill Text CA A.B. 442 (9/30/02): Creates a Public Health Indoor Mold Hazard Fund to be utilized to provide guidance, developing standards, and guidelines regarding permissive exposure limits relating to indoor mold hazards.

2001 Bill Text CA A.B. 2223 (9/30/02): Deals with indoor air quality for schools and provides that unnecessary accumulation of moisture that could lead to mold growth is to be avoided.

2001 Bill Text CA A.B. 2684 (2/22/02): Intent of Legislature to limit the liability of a school district or the governing board of a school district for claims of personal injury or wrongful death resulting from the presence of ‘‘toxic mold’’ on school premises.

2001 Bill Text CA A.P. 3034 (9/18/02): Provides that a residential landlord shall provide written disclosure to prospective tenants of the potential health risks and the health impact that may result from the exposure to mold by distributing a consumer-oriented booklet.

2001 Bill Text CA S.B. 1763 (6/20/02): Provides disclosure requirements for an insurer where mold is ‘‘implicated or likely to be present’’; provides an obligation to ‘‘thoroughly investigate’’; mold is an ensuing loss under the policy (property or liability); mold shall be covered; must be excluded ‘‘clearly, explicitly and in readily understandable terms’’; defines mold as a form of multi-cellular fungi often found in water-damaged building materials.

2001 Bill Text CA S.B. 1846 (6/25/02): Relates to fund of Medi-Cal and Healthy Families and recognizes the Toxic Mold Protection Act of 2002 and funding.

2001 Bill Text CA S.B. 2098 (9/6/02): Recognizes that the Toxic Mold Act imposes various disclosure requirements on landlords, sellers, renters, transferors, and tenants of commercial or industrial properties pertaining to the presence of mold based on knowledge or reason to have notice of the presence of mold.

California Civil Code §§ 1102—1102.18: Requires sellers of real property containing one to four residential units to complete a disclosure form indicating the presence of all environmental hazards, including radon gas, formaldehyde, and mold that are known to the seller. Also requires disclosure of whether property contains a carbon monoxide device. Requires resale of manufactured homes and mobile homes to include disclosure of environmental hazards in the home interior or exterior, including radon, formaldehyde, and lead-based paint, as well as the existence of a carbon monoxide device.

California Education Code §§ 17070.75, 17002(d)(1): Requires school districts to establish a facilities inspection system to ensure schools are maintained in good repair, as a condition of receiving state school facility funds. Defines ‘‘good repair’’ to include interior surfaces free from water damage and showing no evidence of mold or mildew and to include functional and unobstructed HVAC systems. Requires state to develop an evaluation instrument consistent with the criteria set in the law. The Facility Inspection Tool developed by the state for use in school inspections includes several IAQ-related items that address ventilation and mold/water damage.

California Health & Safety Code § 39619.6: Requires the Air Resources Board and the Department of Public Health to conduct a comprehensive study and review of the environmental health conditions in portable classrooms. Directs the study to include a review of design and construction specifications; a review of school maintenance practices; an assessment of IAQ; and an assessment of potential toxic contamination, including mold contamination. Provides that the study shall address the need for modified design and construction standards; emission limits for building materials and classroom furnishings; and other mitigation actions to ensure the protection of children’s health.

California Health & Safety Code §§ 26101—26157: Requires the state health agency to consider the feasibility of adopting permissible exposure limits to mold in indoor environments and, if feasible, to adopt such limits. Establishes criteria to consider in adopting standards, and provides that the department may also adopt alternative standards for facilities that serve people at greater risk of adverse health effects. Provides that the law shall be implemented only to the extent that the department determines that funds are available for its implementation. Establishes disclosure and property maintenance requirements for transferors, lessors, and tenants of real estate following the department’s issuance of standards and guidelines under the law. Authorizes local enforcement of any standards adopted by the department.

California Health & Safety Code §§ 26200—26204: Requires the California Research Bureau, in consultation with the Department of Public Health and with the assistance of a review panel, to perform a study and to publish findings on fungal contamination affecting indoor environments. Requires the study to include information on health effects, assessment, remediation, and hazard communication, among other issues. Requires the California Research Bureau to submit its findings to the legislature and the Director of Public Health.

California Labor Code § 142.3: Authorizes the Occupational Safety and Health Standards Board to adopt occupational safety and health standards that are at least as effective as federal standards. Regulations promulgated under the law (Cal. Code Regs., tit. 8, §§ 5142, 5143) apply to both private and public workplaces, such as schools. The regulations require that HVAC systems be operated continuously and inspected annually, and that HVAC inspection and maintenance records be made in writing and provided to the state and to employees upon request. Additional regulations governing general sanitation (Cal. Code Regs., tit. 8, § 3362) provide that when exterior water intrusion, leakage from interior water sources, or other uncontrolled accumulation of water occurs, those conditions must be corrected because of their potential to cause the growth of mold.


Full text of CA SB655

Full Text of CA SB655

California Department of Public Health, (CDPH) PDF

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