Background Paper for
Candidate National Enforcement Priority:
Air Toxics
January 2010
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What are air toxics and why are air toxics important?
Toxic air pollutants, also known as hazardous air pollutants (HAPs), are a group of 187 pollutants
defined by Congress in the 1990 Clean Air Act Amendments as pollutants of specific concern for
human health that are known or suspected to cause:
o cancer
o other serious health effects, such as reproductive effects or birth defects
o adverse environmental effects such as acid rain
Examples of toxic air pollutants include:
o benzene
o perchlorethlyene
o methylene chloride
o dioxin
o toluene
o metals such as cadmium, mercury, chromium, and lead compounds
Examples of a few of the industrial manufacturing processes that are subject to EPA regulations
regulating HAPs include:
o petroleum refining
o chemical manufacturing
o steel manufacturing
o pulp and paper manufacturing
o surface coating
In 2008-2010, EPA's Air Toxics National Priority focused on the national problem areas of leak
detection and repair, flares, and surface coating. In FY 2010, the Toxics around Schools Initiative was
added to the Air Toxics National Priority to evaluate facilities potentially emitting high levels of HAPs
around schools.
For 2011-2013, EPA is proposing to continue the focus on the national problem areas of leak detection
and repair, flares, and Toxics around Schools. The addition of a geographic initiative to allow regions
to identify and evaluate compliance at large emitters of HAPs in disproportionately affected
geographic areas is being considered.
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Rationale:
Environmental & Human Health Significance
Reducing HAPs contributes significantly to human health protection. People exposed to HAPs at
sufficient concentration and duration may have an increased chance of getting cancer or experiencing
other serious health effects. These health effects can include damage to the immune system, as well as
neurological, reproductive (e.g., reduced fertility), developmental, respiratory and other health
problems. Adverse health effects directly associated with HAPs are of great concern, particularly since
many facilities that emit HAPs are located in industrial, urban areas classified as "non-attainment"
areas for ozone. A large number of HAPs are volatile organic compounds (VOCs) which are
photochemically reactive and, when combined with sunlight, contribute to the formation of ground
level ozone that impairs breathing and exacerbates respiratory illnesses.
In addition to these human health impacts, some HAPs such as mercury deposit onto soils or surface
waters, where plants absorb the metals. Animals ingest food contaminated with HAPs every time a
plant, or animal that ate a contaminated plant, is consumed. The effects of contamination magnify in
intensity up the food chain from plants to larger animals, concentrating the highest levels of pollutants
in the largest predatory animals that consume the greatest volume of food. Like humans, animals may
experience health problems if exposed to sufficient quantities of HAPs over time.
Environmental Justice
Studies suggest that disparities associated with ambient HAPs may have health significance for
populations across racial and income lines. Communities with disproportionate exposure to
environmental risks and those with greater concentrations of sensitive populations may benefit in
particular from the reduction of HAPs.
Non-Compliance Data
Leak Detection and Repair (LDAR): LDAR continues to be a productive enforcement target with
potential for significant emission reductions and injunctive relief. EPA currently has over 90 LDAR
investigations underway and continues to identify significant levels of non-compliance in this
regulatory program. Five of the ten EPA regions still have large numbers of facilities at which to
evaluate LDAR compliance.
Flares: Large emissions of HAPs from improperly operated industrial flares were recently identified as
a significant compliance problem. In the 2008-2010 planning cycle, EPA initiated a focus on this
national problem area and began to build capacity in the regions to identify and address non-
compliance. EPA continues to find extremely high levels of HAP emissions from flares, with single
flares emitting 300 to 500 tons per year of HAPs.
Toxics around Schools: This compliance monitoring and enforcement initiative complements the
Agency's effort to monitor the HAPs around selected schools throughout the U.S. Since this initiative
was just added to the Air Toxics National Priority in FY 2010, continued focus for 2011-2013 is
warranted to better assess the contribution of regulated HAPs to the overall problem and address non-
compliance where appropriate
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Geographic Initiative: Throughout this country there are a number of communities disproportionately
impacted by pervasive and persistent emissions of air toxic pollutants from large and small sources.
All too frequently, the residents of these communities rely on these same sources for employment and
are constrained in their choice of housing locations. Studies show that people living in some of these
communities have elevated concentrations of toxins in their blood and more instances of air toxics-
related illnesses. EPA recognizes that any strategy to address local impacts of air toxics should
account for the fact that the levels and types of air toxics vary widely from community-to-community
depending upon a number of factors including the amount and types of industry and smaller sources,
both stationary and mobile.
The addition of a geographic initiative to allow the regions to identify and assess compliance at large
emitters of HAPs in disproportionately affected areas selected by each region is being considered.
EPA proposes to collaborate with states/local agencies, tribes, and communities to aggressively reduce
air toxics within at-risk communities.
Federal Government Role
A key role for the Federal government is to assure that industries nation-wide meet Clean Air Act
requirements to use best technologies available to control HAPs, known as maximum achievable
control technology standards or MACT standards. EPA is well suited to take this action based on the
number of facilities subject to LDAR and flare requirements that are owned by companies operating
similar facilities in different states across the nation. Evidence indicates that these violations have
existed for a long time and may not be identified during routine Federal and state inspections given the
complexity of the compliance evaluation necessary to determine the compliance status of a facility.
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