U.S. mercury rule lets hazardous air pollutants off the hook
On March 15, the U.S. EPA issued the long-awaited and controversial rule establishing trading as the mechanism for reducing mercury emissions from coal-fired plants. Although the debate over the rule focused on how best to control mercury releases, critics say that an opportunity to also regulate several other hazardous air pollutants (HAPs), such as dioxins, arsenic, and lead, may have been lost.
The Clean Air Mercury Rule (CAMR) establishes the United States as the first nation in the world to address mercury from this pollution source. When combined with the new Clean Air Interstate Rule (CAIR), the provisions for power plants should ultimately cut mercury emissions by as much as 70% from 1999 levels, sometime after 2018, EPA officials say.
CAIR, which was announced on March 10, is designed to control SO2 and NOx emissions. To do that, utilities most likely will install wet scrubbers and selective catalytic reduction systems, which capture mercury as a co-benefit, EPA notes in the regulatory determination it published in advance of CAMR (Fed. Regist. 2005, 70 [50], 15,994–16,035). Indeed, these technologies might control several HAPs, says EPA’s Jason Burnett, who declined to name which HAPs might be captured. “We have decided that after the implementation of CAIR and CAMR [any HAPs of potential concern] won’t pose a hazard to human health,” says Burnett, policy advisor to Jeffrey Holmstead, assistant administrator for air and radiation.
Environmentalists and many scientists have argued that mercury should be regulated under section 112 of the 1990 amendments to the Clean Air Act (CAA). This section requires that each plant install the maximum achievable control technology (MACT) and address the 189 HAPs listed in CAA found to pose a risk. That was also the view EPA finalized in the last days of the Clinton Administration.
In its Utility Air Toxics Study, sent to Congress in 1998, EPA wrote that it identified 67 HAPs as potentially being emitted by these plants, and 14 of these were earmarked for further evaluation. When it issued its final determination in 2000 that coal-fired plants should be regulated under section 112 (Fed. Regist. 2000, 65 [245], 79,825–79,831), EPA wrote that its evaluation showed that emissions of arsenic, as well as the metals chromium and cadmium, pose a potential cancer risk. Dioxins, hydrogen chloride, and hydrogen fluoride “are three additional HAPs that may be of potential concern and may be evaluated further through the regulatory development process,” the agency added in 2000.
Under the Bush Administration, EPA argues that these pollutants don’t need to be controlled at each power plant. There is too much data uncertainty to regulate mercury emissions under section 112, the agency writes in its regulatory determination. As for other nonmercury HAPs, these emissions don’t rise to the level of cancer risk for humans, and therefore don’t need regulation under the CAMR, says Burnett. However, “EPA does acknowledge that science continues to evolve and that we need to keep looking at a number of HAPs,” he adds.
Those at most risk live close to the power plants, where mercury hot spots occur, scientists and others say (Environ. Sci. Technol. 2004, 38, 126A–127A). About 156 million people in the United States live within 30 miles of a coal-fired power plant, points out John Stanton of the National Environmental Trust (NET), a nonprofit environmental group. He adds that about 460 U.S. coal-fired power plants burn more than 900 million tons (t) of coal every year—42% of all emissions reported to EPA under the Toxics Release Inventory. Indeed, they are the largest emitter of toxic gases, arsenic, and chromium and are the second-largest source of lead and dioxin air pollution, NET notes in the 2004 report Beyond Mercury.
Still, CAMR presumably doesn’t bar EPA from someday regulating other HAPs from power plants, says Amar Praveen of the Northeast States for Coordinated Air Use Management, an association of air quality control divisions. John Millett, an EPA spokeperson, agrees, saying that nothing in the new determination takes away EPA’s authority to regulate HAPs under section 112 but that such a move would require further study.
Nevertheless, air- and water-quality regulators in several states have strongly objected to the new CAMR. “This rule inappropriately allows trading of mercury, which is a powerful neurotoxin, rather than requiring state-of-the-art control at each facility,” says Bill O’Sullivan, director of the division of air quality in New Jersey’s Department of Environmental Protection. “To compound matters, the rule does nothing to control a host of other toxic air pollutants that power plants emit, including arsenic and cadmium.” New Jersey’s attorney general filed a lawsuit on March 29 on behalf of a coalition of eight northeastern states plus California.
CAMR was welcomed by the industry because it offers plant operators flexibility in meeting the standards and doesn’t require every plant to install controls. It sets a national cap on mercury emissions of 38 t beginning in 2010; an additional 15 t must be trimmed by 2018. Once up and running, the program will be fairly simple: Individual plants will receive a specific emissions cap. If emissions fall below the cap, the plant owner can sell the emission “credits” to another facility, where they can be used to increase emissions and still meet the second facility’s cap. The actual CAMR had not been published at press time. For information on HAPs and CAMR, see www.epa.gov/mercury/control_emissions/decision.htm.
