California Air Resources Board

Hexavalent chromium is a known human carcinogen, and prolonged exposure may cause lung cancer. In 1986, the California Air Resources Board (CARB) categorized hexavalent chromium as a Toxic Air Contaminant (TAC) with no safe exposure levels. Hexavalent chromium has the second highest cancer potency of identified TACs (second only to dioxin) and is about 500 times more toxic than diesel exhaust particulate matter (diesel PM).  

Health and Safety Code section 39666 requires CARB to adopt air toxic control measures (ATCMs) to reduce emissions of TACs to protect public health. When adopting or amending ATCMs, if no safe threshold exposure level is identified for the TAC, the ATCM is to reduce emissions to the lowest level achievable level through the application of best available control technology (BACT) or a more effective control method unless CARB determines, based on an assessment of risk, that an alternative level of emission reduction is adequate or necessary to prevent an endangerment of public health.

The 2023 Chromium Plating ATCM, effective on January 1, 2024, addresses these requirements and delivers substantial health benefits. This ATCMis the most stringent regulation of hexavalent chromium emissions from the chrome plating industry, compared to federal standards and local District rules. This ATCM will reduce and ultimatelyeliminate hexavalent chromium emissions from California's chrome plating industry, thereby reducing the potential cancer risk for people living or working near chrome plating facilities and minimize occupational exposures for on‑site workers.

ATCM Regulatory History

In 1988, CARB adopted the first ATCM to reduce hexavalent chromium emissions from both decorative and hard chrome plating facilities, as well as chromic acid anodizing operations. This measure reduced overall emissions from these facilities by 97 percent. The emission standards have been met by utilizing add-on pollution control devices such as High Efficiency Particulate Air (HEPA) filters, packed bed scrubbers, and/or by adding fume suppressants to the plating tanks.

In 1998, the ATCM was amended to establish equivalency with federal standards. These amendments did not change the limits already in place but established separate limits for new sources. These amendments to the ATCM continued to divide hard chrome plating operations into three tiers (Large/Medium/Small) for existing sources but established two tiers (Large and Medium/Small) for new sources. For hard chrome plating, the ATCM required operations to comply with an emission limitation expressed in terms of milligrams of hexavalent chromium emissions per ampere-hour (mg/amp-hr). The applicable emission limitation depended on the chrome plating source size (both in terms of mass emissions and ampere-hour usage). The largest hard chrome plating operations had to meet a control efficiency of over 99 percent. Decorative chrome plating and chromic acid anodizing facilities were required to use chemical or mechanical fume suppressants to reduce hexavalent chromium emissions by 95 percent. In addition to emission requirements, chrome plating and chromic acid anodizing operations were required to conduct a performance test to demonstrate compliance. The ATCM also required regular inspections and maintenance, parameter monitoring, operation and maintenance plans, and recordkeeping.

On December 7, 2006, the Board approved amendments to the ATCM for Chrome Plating and Chromic Acid Anodizing Operations. Subsequently, these amendments were officially adopted on August 9, 2007, and became legally effective on October 24, 2007. These adopted amendments established some of the most stringent emission control requirements in the nation at that time. These requirements were generally applicable, with exceptions for small facilities. They mandated either the installation or the upgrade of add-on air pollution control devices for chrome plating tanks. Depending on their proximity to sensitive receptors and total throughput, these requirements phased in between April 24, 2008, and October 24, 2011. The compliance deadline to meet emission control requirements was set for October 24, 2009, particularly for those facilities situated within 330 feet of sensitive receptors and those with higher throughputs.