Of all the states in the US, California has long been the most active in environmental regulation.  As far back as 1988, the California Air Resources Board (CARB) adopted an ATCM (airborne toxic control measure) on chromium emissions which was the forerunner of the national EPA regulation introduced seven years later – and which led to the closing of a significant number of Californian hard chrome plating shops.

According to the CARB, both Cr6+ and nickel are human carcinogens that contribute to cancer and other adverse health effects.  Nickel is considered less hazardous than Cr6+, although more harmful than the cleaning solvent trichloroethylene.  As a result of these classifications, several coating processes that involve Cr6+ or nickel are now regulated in California, together with certain coatings.

Chrome plating and chromic acid anodizing

California’s original ATCM on hard and decorative chrome plating and chromic acid anodizing, which applies to all chrome plating and anodizing facilities established before 1998, resembles the current EPA regulation on chromium compound emissions but is more stringent.  Whereas the emission limits in the EPA’s rule are concentration-based (in terms of mg m-3 of exhaust air), the original California rule has emission limits that depend on the ampere-hours used in the plating or anodizing process.  In addition, the definitions of a large and small facility differ in the two rules.

An amended ATCM was issued in 1998, bringing the California regulation into line with EPA standards.  However, the amended concentration-based rule applies only to new (installed after 1998) facilities, and older facilities are still subject to the previous rule based on ampere-hours.  The 1998 amendment also establishes two tiers of size (large and medium/small) for new facilities, although older facilities continue to be divided into three tiers (large, medium and small) regulated by the original rule.

Thermal spray

Possibly the first regulation of its kind worldwide, the California ATCM on thermal spray that went into effect on September 30, 2005 strictly limits Cr6+ and nickel emissions from thermal spraying processes that use materials containing chromium, nickel and their compounds.

This came about despite the fact that thermal spray is one of the most commonly used technologies for replacement of hard chrome plating, which is already under strong environmental pressures itself because of Cr6+ emissions.  Several studies have documented formation of Cr6+ during plasma or arc spraying, but the primary studies cited had no relevance to actual operating conditions.  It has been found that any thermal spray of Cr-containing powder produces some Cr6+ emissions, but that HVOF production of Cr6+ is negligible.

The principal features of the rule are:

  1. All Cr6+ and nickel emissions from thermal spray operations must pass through an appropriate control device, which can range from a water curtain to a high-efficiency filter, the type of device being determined by the calculated annual emissions from that operation
  2. In the case of nickel, maximum hourly emissions from all thermal spraying operations must not exceed 0.01 lb from an individual source (such as a stack) or 0.1 lb from the whole facility
  3. A facility is exempt from the requirements when annual emissions of Cr6+ and nickel are less than 0.001 lb and 0.3 lb, respectively, from an individual source; and less than 0.004 lb and 2.1 lb, respectively, from the whole facility
  4. Requirements on permitting, monitoring, record keeping and reporting must be met.

Automotive coatings

Similar to Europe’s ELV directive, a California ATCM banning Cr6+ and cadmium in coatings for motor vehicles and mobile equipment became effective on January 1, 2003.  Unlike the ELV rule that allows a maximum concentration of 0.1 wt.% of Cr6+ and cadmium (as well as lead and mercury) in automotive coatings, the Californian regulation prohibits their use altogether in vehicles and equipment sold after the effective date.  The California rule also applies to a much broader range of equipment than ELV, and includes off-road vehicles, trains, agricultural equipment, concrete mixers and even wheelchairs.  The ATCM restrictions had already applied locally in two parts of the state, the South Coast Air Quality Management District and the Antelope Valley Air Pollution Control District, from 1996.


California has recently passed laws similar to the EU WEEE and RoHS directives.  Since January 1, 2005, the state’s Electronic Waste Recycling Act has imposed a fee on “covered electronic devices” currently being sold in California, in order to fund a payment system for the proper collection and recycling of these products at the end of their service life.  The same legislation also requires covered devices sold in the state after January 1, 2007 to meet the same requirements as those found in the RoHS rule.  However, the product range in the Californian law is much more limited than in the WEEE and RoHS regulations, being restricted to certain video displays.

A new law, effective from February 9, 2006, requires California households and small businesses to keep “universal waste” out of the trash.  Universal waste (u-waste) is a category of hazardous wastes that includes electronic devices, batteries, fluorescent tubes, mercury-containing items including electrical switches, and many other items.