EPA has been developing programs to cut emissions
of these commonly found air pollutants since the
Clean Air Act was passed in 1970. It's a big job, and
although a great deal of progress has been made, it
will take time to make the air healthy throughout
the country. For the latest information on air quality
trends in the U.S., visit www.epa.gov/airtrends. There
are still several areas of the country, including many
large cities, that are classified as nonattainment for
at least one of the six common pollutants. Despite
continued improvements in air quality, millions of
people live in areas with monitoring data measuring
unhealthy levels of pollution.
To see whether your area is attainment or
nonattainment, contact your local air pollution
control agency or visit EPA’s website at: www.epa.
gov/air/urbanair.
Particle Pollution
Particle pollution, also known as particulate matter
(PM), includes the very fine dust, soot, smoke, and
droplets that are formed from chemical reactions,
and produced when fuels such as coal, wood, or
oil are burned. For example, sulfur dioxide and
nitrogen oxide gases from motor vehicles, electric
power generation, and industrial facilities react with
sunlight and water vapor to form particles. Particles
may also come from fireplaces, wood stoves,
unpaved roads, crushing and grinding operations,
and may be blown into the air by the wind.
EPA scientists and other health experts are concerned
about particle pollution because very small or "fine"
particles can get deep into the lungs. These fine
particles, by themselves, or in combination with other
air pollutants, can cause increased emergency room
visits and hospital admissions for respiratory illnesses,
and tens of thousands of deaths each year. They can
aggravate asthma, cause acute respiratory symptoms
such as coughing, reduce lung function resulting in
shortness of breath, and cause chronic bronchitis.
The elderly, children, and asthmatics are particularly
susceptible to health problems caused by breathing
fine particles. Individuals with pre-existing heart or
lung disease are also at an increased risk of health
problems due to particle pollution.
Particles also cause haze reducing visibility in places
like national parks and wilderness areas that are
5
Particle Pollution
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diesel.
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Protecting the Public from
EPA is tackling particle pollution in several different
EPA's health-based standards include limits for
smaller-sized or "fine" particles. States are taking
actions to meet these standards. To learn more, visit
www.epa.gov/particles.
EPA's rule for Clean Diesel Trucks and Buses will
result in a fleet of heavy-duty trucks and buses
that will be 95 percent cleaner than today's trucks
and buses. To learn more, visit www.epa.gov/otaq/
Visibility protection regulations are designed to
reduce emissions that cause haze in our national
parks and wilderness areas. States are working
together on strategies to improve visibility in these
natural areas. To learn more, visit www.epa.gov/
visibility.
EPA created the Air Quality Index (AQI) to provide
simple information on local air quality, the health
concerns for different levels of air pollution,
and how people can protect their health when
pollutants reach unhealthy levels. To learn more,
visit www.airnow.gov.
known for their scenic vistas. These are places where
we expect to see clearly for long distances. In many
parts of the United States, pollution has reduced the
distance and clarity of what we see by 70 percent.
Fine particles can remain suspended in the air and
travel long distances with the wind. For example, over
20 percent of the particles that form haze in the Rocky
Mountains National Park have been estimated to come
from hundreds of miles away.
Particles also make buildings, statues and other outdoor
structures dirty. Trinity Church in downtown New York
City was black until a few years ago, when cleaning off
almost 200 years worth of soot brought the church’s
stone walls back to their original light pink color.
Before the 1990 Clean Air Act went into effect,
EPA set limits on airborne particles smaller than 10
micrometers in diameter called PM
10
. These are tiny
particles (seven of these particles lined up next to each
other would cover a distance no wider than a human
hair). Research has shown that even smaller particles
(1/4 the size of a PM
10
particle) are more likely to
harm our health. So in 1997, EPA published limits for
fine particles, called PM
2.5
. To reduce particle levels,
additional controls are being required on a variety of
sources including power plants and diesel trucks.
Particle Pollution