The Bay Area Air Quality Management District (BAAQMD) is considering the removal of a long-standing exemption for the use of a common dry cleaning solvent, perchloroethylene or "perc". The removal of this exemption is the latest in a series of regulatory and technological changes that may move the dry cleaning industry towards hydrocarbon-based solvents, or away from chemical solvents altogether.
Perchloroethylene is considered by the US EPA and Cal/ EPA's Office of Health Hazard Assessment to be a potential human carcinogen. Prolonged exposure to perc also causes a number of acute health effects, including skin and eye irritation, breathing and neurological problems, burns and blistering.
Regulation of the use of perc in dry cleaning has a long and complex history, including multiple regulations at both the federal and state level. Under the federal Clean Air Act, perc is listed as a Hazardous Air Pollutant; the California Air Resources Board lists it as a Toxic Air Contaminant. Several regulations have been put in place to establish levels for substances on these lists, including the Air Toxics Hot Spots Program, a fusion of federal and state laws dating back to 1987, and the Clean Air Act's Toxics New Source Review Program (TNSR). The BAAQMD is responsible for implementing both programs for approximately 1000 dry cleaning facilities in the nine Bay Area counties.
Under TNSR, new and modified potential sources of toxic air pollution undergo a risk screening analysis. As part of TNSR, the BAAQMD developed a Risk Management Policy (RMP) that includes standards designed to minimize health risks to the public from a toxic air pollution source. Sources that exceed a cancer risk of one-in-a-million require Best Available Control Technology (BACT) and sources that exceed a risk of 10-in-a-million may be denied a permit by the district. (According to district information on Toxic Air Contaminants, the risk of cancer due to background concentrations of contaminants in Bay Area air is 600 chances in a million.) From 1987 to 1991 the BAAQMD required new dry cleaners to meet a 10-in-a-million risk level under such a RMP, if the dry cleaning machine met BACT criteria (a closed-loop system with refrigerated condenser). Special ventilation systems were sometimes installed in order to meet the 10-in-a-million standard.
In 1991 the Office of Environmental Health Hazard Assessment (OEHHA) of Cal/EPA revised the cancer potency value for perc, increasing the calculated risks by a factor of ten. Suddenly, no standard drycleaner could meet even the 10-in-a-million risk level. The District therefore modified the RMP to allow risks up to 100-in-a-million for dry cleaners. The modified exemption includes several control measures. For example, it currently requires that drycleaners use an advanced closed-loop perc machine with secondary controls to absorb perc vapors. In addition, a dry cleaning facility often must capture and vent its perc vapors through an exhaust stack.
While the RMP affects new and modified drycleaning operations, additional regulations have been put in place for existing dry cleaning facilities. In 1994, the state issued an Airborne Toxics Control Measure (ATCM) for the dry cleaning industry in order to reduce risk from existing dry cleaning facilities, and BAAQMD adopted a rule to implement the ATCM in the Bay Area. Most Bay Area dry cleaners met this statewide rule without any additional risk reduction measures.
For approximately twenty percent of facilities, however, additional measures were necessary, especially if the facility was located close to people who might be exposed. One common scenario is a dry cleaner located on the first floor of an apartment building. Control measures involved establishing work practice standards, operator training programs, preventative maintenance on machinery, secondary control systems, and ventilation built to discharge vapors well away from areas where people could be exposed. The more extreme measures involved special vapor barrier rooms with metallic linings impervious to perc vapors.
Dry cleaning technology has changed considerably in the last ten to fifteen years, and as a result, air districts around the state are considering or implementing changes in the regulation of perc. As part of a general overhaul of the District's TNSR program, the BAAQMD is considering the removal of the exemption provided by the 1991 Risk Management Policy. Removing the exemption would require new dry cleaning machines to meet the same 10-in-a-million risk level applied to all other new toxic air pollution sources.
Brian Bateman, Air Quality Engineering Manager for the BAAQMD, says that if drycleaners maintain their existing perc machines, they should be able to meet the proposed 10-in-a-million risk standard that will apply when the 1991 exemption is removed. Drycleaners who install new perc machines may also be able to meet the standard. However, a number of Bay Area drycleaners that have higher risks, such as greater solvent usage or being located near a sensitive population, may be unable to meet the requirement. These facilities may be required to switch to a non-perc dry cleaning system.
In December of 2002, the South Coast Air Quality Management District (SCAQMD) adopted a rule banning the purchase of perc dry cleaning machines after January 1, 2003, except for some replacement machines. In additon, the SCAQMD rule requires the phase-out of perc machines at the end of their useful life, with a final phase-out date of 2020. BAAQMD's proposed rule would parallel the SCAQMD rule, but would not include an explicit ban on perc. Bateman notes, however, that seventy percent of new dry cleaning machines currently sold in the Bay Area are non-perc machines.
Some of the alternatives to perc that have been developed in the last few years include a high flash-point hydrocarbon solvent marketed by Exxon under the name DF2000, and a silicone-based solvent marketed by General Electric under the name GreenEarth. Concerns have recently arisen about the potential toxicity of Green Earth's primary component, decamethylcyclopentasiloxane; at this time, Exxon DF2000 remains the primary alternative to perc. Other dry cleaning alternatives involve the use of high pressure liquid carbon dioxide, or "wet cleaning", a high-tech version of soap and water. According to a recent article in Consumer Reports (February 2003), carbon dioxide and silicone-based cleaners work well, providing even better results than perc.
The BAAQMD plans to announce the proposed rule change on its web site and through its interested parties mailing list. It will host four to six workshops in May and June (see below) to solicit input on the rule, and plans to send the proposed rule to its Board in June for approval.
Ann Blake
Workshops
The changes in the regulations for dry cleaners are part of the proposed changes to the Bay Area Air Quality Management District's Air Toxics New Source Review program. Public workshops on all of the changes are under way. June workshops will be held as follows:
All workshops are from 6:30-8:30 pm, and will have Spanish translation available. Additional information is on the BAAQMD Website, http://www.baaqmd.gov/ruledev/workshop.htm, or at 415-771-6000.
For more information: BAAQMD, 415-771-6000