Geoscience Reference
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ecologic implications, identify sources of exposure, and trace the pathways of hu-
man exposure. In addition to the traditional single-substance approach, the recog-
nition that the population is chronically exposed to low concentrations of large
numbers of pollutants will necessitate new methods for understanding cumulative
effects of multiple contaminants on health.
Air Pollution and Climate Change
EPA's first goal in its 2011-2015 strategic plan is “taking action on cli-
mate change and improving air quality” (EPA 2010a). This goal encompasses
mandates under the Clean Air Act and other statutes, obligations under interna-
tional treaties and agreements, and executive branch commitments. The follow-
ing sections provide examples of challenges associated with understanding and
addressing air pollution and climate change.
Improving Air Quality
The Clean Air Act is designed primarily to address effects on human
health and welfare (including visibility and ecologic effects) that are due to pol-
lutants released into or produced in the ambient atmosphere. That is accom-
plished through regulations that limit emissions from a broad array of sources—
feedlots, ship engines, petroleum refineries, power plants, vehicles, and more.
The act requires EPA to protect human health and welfare through provisions
that specifically address a core set of six criteria air pollutants, nearly 200 listed
hazardous air pollutants, acid deposition, and protection of the stratospheric
ozone layer (42 USC [2008]). It also directs the EPA administrator to regulate
other air pollutants on finding they may reasonably be expected to endanger
public health and welfare. The Clean Air Act and other statutory mandates give
rise to the need for improved scientific and technical information on health ef-
fects, human exposures, ecologic exposures and effects, ambient and emission
monitoring techniques, atmospheric chemistry and physics, and pollution-
prevention and emission-control methods for hundreds of pollutants.
Beyond the outdoor air-quality focus under the Clean Air Act, some pro-
grams are designed to address indoor air quality. Many Americans spend 65% to
over 90% of their time indoors (Allen et al. 2007; Wallace and Ott 2011). Expo-
sures to certain pollutants released from building materials and consumer prod-
ucts are often substantially greater indoors than outdoors (Hoskins 2011). EPA
has extensive authority over chemicals and microbial agents found or used in the
indoor environment under environmental laws including the Toxic Substances
Control Act and the Federal Insecticide, Fungicide, and Rodenticide Act. It also
sets the guideline for acceptable levels of radon in indoor air. EPA is a leader in
understanding the dynamics of vapor intrusion from soil gas into buildings and it
conducts research on human exposure in the indoor environment and corre-
sponding health effects (EPA 2005, 2011c, 2012a,b,c).
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