Reducing Emissions of Hazardous Air Pollutants

What is Being Done to Reduce Hazardous Air Pollutants?

EPA and our regulatory partners at the State and local level have taken significant steps to dramatically reduce toxic air pollutants and provide important health protections for Americans nationwide. These steps include: reducing toxic emissions from industrial sources; reducing emissions from vehicles and engines through new stringent emission standards and cleaner burning gasoline; and addressing indoor air pollution though voluntary programs. See further details below about reductions from:

Industrial Source Programs

Major Sources

The Clean Air Act requires the EPA to regulate hazardous air pollutants (HAP) from large industrial facilities known as major sources in two phases.

The first phase is “technology-based,” where the EPA develops standards for controlling the emissions of air toxics from sources in an industry group (or “source category”). These maximum achievable control technology (MACT) standards are based on emissions levels that are already being achieved by the controlled and low-emitting sources in an industry.

Within 8 years of setting the MACT standards, the Clean Air Act directs the EPA to assess the remaining health risks from each source category to determine whether the MACT standards protect public health with an ample margin of safety, and protect against adverse environmental effects. This second phase is a “risk-based” approach called residual risk. Here, the EPA must determine whether more health-protective standards are necessary.

Also, every 8 years after setting the MACT standards, the Clean Air Act requires that the EPA review and revise the MACT standards, if necessary, to account for improvements in air pollution controls and/or prevention.

Since 1990, EPA has issued regulations limiting emissions of air toxics from more than 174 categories of major industrial sources including chemical plants, oil refineries, aerospace manufacturers, and steel mills. The requirements in a number of these regulations took effect between 1999 and 2011. When fully implemented, these standards are projected to reduce annual air toxics emissions by about 1.7 million tons.

Area Sources

The EPA has also completed all of the required emissions standards for smaller sources known as area sources. Individual area source facilities typically have much lower emissions, but these sources can be numerous and widespread, including in locations that are heavily populated.  In some urban areas, the sum of area source emissions for a category can be much greater than emissions from major sources.  Examples of area sources are gas stations and dry cleaners. Measured from the 1990 baseline inventory, we have subjected between 90 and 100 percent of the area  sources of urban air toxic pollutants to standards and have subjected 90 percent of the sources of seven potentially bio-accumulative toxic pollutants to standards.  We project that all of the regulated area sources will be in compliance no later than 2014. 

The EPA's area source program also includes a community support component because communities with disproportionate risks may be able to reduce some toxic sources more quickly and effectively through local initiatives rather than through national regulations. The NATA is a tool that state/tribal and local agencies, as well as communities can use as a component of a local air toxics evaluation to determine potential pollutants and areas for further review.

Learn more about EPA's regulation of air toxics from industrial sources and EPA's area source program.

Learn more about Urban Air Toxics

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Mobile Source Programs

Mobile source emissions have been reduced by approximately 50 percent, about 1.5 million tons of HAPs a year since 1990. With additional fleet turnover, we expect these reductions to increase to 80 percent by the year 2030.  In addition, mobile source diesel onroad and nonroad particulate matter decreased by about 27 percent from 1990 to 2005. Significant additional reductions (roughly 90 percent) are projected from 2005 to 2030 as many of the recent mobile source rules targeting diesel engines go into effect.

The EPA’s most recent regulatory program that significantly reduces mobile source air toxics are Tier 3 vehicle and fuel standards, issued in 2014, which will reduce emissions of air toxics from motor vehicles between 10 and 30 percent by 2030, depending on the pollutant.

Another regulatory program that reduced mobile source air toxics was the 2007 mobile source air toxics rule, which controlled the benzene content of gasoline, as well as vehicle emissions at cold temperatures and emissions from portable fuel containers.  A recent assessment in Anchorage, Alaska, suggested that the fuel benzene standard alone reduced ambient benzene concentrations by more than 50percent.  

Other programs that are reducing mobile source air toxics are low-sulfur gasoline and diesel requirements, heavy-duty engine and vehicle standards, controls for small spark-ignition engines and recreational marine engines, the locomotive and commercial marine rule, standards for nonroad diesel engines, and the North American and Caribbean Emission Control Areas (ECAs) established to reduce emissions from ships.

Non-regulatory initiatives are also reducing mobile source air toxics.  Examples include the National Clean Diesel Campaign, Clean School Bus USA, SmartWay, and EPA’s Ports Initiative.  In addition, EPA's Diesel Emissions Reduction Program (known as "DERA") was created to deploy pollution-controlling technologies in diesel fleets. Clean diesel projects yield an immediate public health and air quality benefit. The EPA estimates that for every dollar invested in reducing diesel exhaust, a community may achieve up to 13 dollars in public health benefits. From 2008 to 2013, the EPA awarded $569 million to retrofit or replace nearly 73,000 engines in vehicles, vessels, locomotives or other pieces of equipment. The EPA estimates that these projects will reduce emissions by 14,700 tons of PM2.5 over the lifetime of the affected engines. 

Learn more about EPA’s clean diesel program.  

Learn more about EPA's programs to reduce air toxics from mobile sources.

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Indoor Air Programs

The EPA also promotes many programs to help reduce indoor air toxics in homes, schools, and in the workplace. Programs for homes include information on best practices for remodeling, reducing radon, advice on adequate and proper ventilation, and effective non-chemical strategies for pest control. Improving indoor air in schools is also a major focus as there are numerous, common sources of indoor air pollution found in schools. These include art, science, and cleaning supplies, asthma triggers like dust mites and molds, and diesel exhaust from school buses. The EPA has an action kit for schools to help identify and reduce these sources of indoor air pollution. Office buildings can also have significant sources of indoor air pollution. The EPA has teamed up with professional engineers, along with building and architect associations to develop a free indoor air design guide for architects, design engineers, and contractors. This guide provides reference materials for building professionals and for the public.

Learn more about indoor air activities.

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