California Air Resources Board

The Board identified hexavalent chromium as a toxic air contaminant (TAC) in January 1986. The Board found, based on epidemiological and animal studies, that hexavalent chromium should be considered a human carcinogen for which there is no safe threshold exposure level. At that time, the Department of Health Services (DHS), now the Office of Environmental Heather Hazard Assessment (OEHHA), predicted a theoretical excess cancer risk of up to 146 in one million for a 70-year exposure to 1 ng/m³ of hexavalent chromium. This finding was consistent with that of the Scientific Review Panel on Toxic Air Contaminants.

In 1988, an Airborne Toxic Control Measure (ATCM) was adopted 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 for Chrome Plating and Chromic Acid Anodizing operations 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.

In an effort to further protect the public, amendments to the ATCM for Chrome Plating and Chromic Acid Anodizing Operations were presented and approved by the Board on December 7, 2006. These amendments were subsequently adopted on August 9, 2007, and became legally effective on October 24, 2007. The adopted amendments set forth the most stringent emission control requirements in the nation. Generally, except for small facilities, the limits require the installation or the upgrade of add-on air pollution control devices at the plating tank. Based on proximity to sensitive receptors and total throughput, the requirements became effective between April 24, 2008, and October 24, 2011. The compliance date to meet emission control requirements was October 24, 2009, for facilities with sensitive receptors within 330 feet and/or those with higher throughputs.In addition, in Resolution 06‑25, in which the amendments were approved, ARB staff was directed to track compliance with the ATCM.  A Summary of Compliance with the ATCM was published in October 2011.