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Background
Mobile Source Air Toxics: An Avoidable Threat
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What Are Mobile Source Air Toxics?
Mobile source air toxics are the most hazardous pollutants emitted by mobile sources such as cars, trucks, buses, boats, snowmobiles, construction equipment, and lawnmowers. EPA has identified 21 mobile source air toxics, including benzene, formaldehyde, 1,3-butadiene, acetaldehyde, and diesel particulate matter, all of which can cause cancer or other serious health problems.
Impacts on Public Health
Mobile source air toxics are pollutants designated (or listed) as "hazardous" by the Environmental Protection Agency under the Clean Air Act and emitted by mobile sources such as cars, trucks, buses, boats, snowmobiles, construction equipment, and lawnmowers. EPA has identified 21 mobile source air toxics, including benzene, formaldehyde, 1,3-butadiene, acetaldehyde, and diesel particulate matter, all of which can cause cancer or other serious health problems.
Each year, mobile sources emit more than 700,000 tons of benzene, formaldehyde, 1,3-butadiene, acetaldehyde, and diesel particulates. They also emit more than one million tons of other hazardous air pollutants (66 Fed. Reg. at 17238-17239). By volume, mobile sources account for about 40 percent of all emissions of hazardous air pollutants.
The detrimental health effects of this group of pollutants are severe and subject Americans to unacceptable levels of risk for cancer, neurological and reproductive disorders, blood disease, birth defects, developmental damage, kidney and liver damage, and respiratory disease.
The Law
As Congress recognized in 1990, toxic emissions from mobile sources can be substantially reduced. The Clean Air Act amendments of 1990 required EPA to complete by 1992 a study of mobile source air toxics and, in particular, of the health risks they pose (42 U.S.C. § 7521(1)(1)). Following the study, EPA was required to promulgate by 1995 regulations "based on the study...to control hazardous air pollutants from motor vehicles and motor vehicle fuels" (42 U.S.C. § 7521(1)(2)). EPA was required to include standards for fuels, vehicles, or both that "reflect the greatest degree of emission reduction achievable through the application of technology which will be available, taking into consideration [EPA's other mobile source regulations], the availability and cost of the technology, and noise, energy, and safety factors and lead time" (Id). EPA also was required to establish regulations that "at a minimum, apply to emissions of benzene and formaldehyde."
EPA's Failure to Implement the Law
Although EPA has had more than ten years to study the problem of mobile source air toxics, the agency has never completed a thorough analysis. Notably absent from EPA's study is any evaluation of the cumulative risk presented by mobile source air toxics; instead, the study discusses the risks posed by only one pollutant at a time. The study also omits any discussion of health risks other than cancer from mobile source air toxics. The study does not address risks resulting from exposure to these toxics through contaminated food and water. Finally, the study ignores the heightened risks to highly exposed and highly sensitive individuals.
Released in March 2001 -- six years late -- EPA's mobile source air toxics regulations are an even more serious breach of the Clean Air Act than EPA's study because they do not reflect the greatest degree of emissions reduction achievable. Recognizing that its regulations are far less than what the law requires, EPA has committed to promulgate another mobile source air toxics rule in 2004.
With respect to fuels, EPA established only an "anti-backsliding requirement," which prohibits refiners from allowing the toxics content in their fuel to increase beyond the levels achieved between 1998 and 2000. Refiners have reduced their benzene levels below 1 percent in areas where reformulated gasoline is required, and in most cases have achieved reductions to 0.6 percent. Elsewhere, benzene levels are as high as 5 percent. By requiring similar benzene reductions nationwide, EPA could reduce benzene levels in some parts of the country by as much as 90 percent. Under EPA's rule, benzene levels in most of the country will remain high. Refiners can increase the levels of the most toxic substances in gasoline (including benzene) so long as they proportionally decrease the levels of other, less toxic pollutants. Thus, EPA's regulations require no reductions -- and actually allow increases -- of the worst mobile source air toxics.
EPA did not require any vehicle emissions reductions at all.
Because EPA's regulations yield no real reductions of mobile source air toxics from either fuel or vehicle improvements, Americans still do not have the protection that Congress intended them to have six years ago. With the current timeline, those protections are unlikely to be implemented before 2004 -- almost ten years late.
Public Health Threats
Control Options for Mobile Source Air Toxics
References
