Health and Environment
The size of particles is directly linked to their potential for causing health problems. Small particles less than10
micrometers in diameter pose the greatest problems, because they can get deep into your lungs, and some
may even get into your bloodstream.
Exposure to such particles can affect both your lungs and your heart. Small particles of concern include
"inhalable coarse particles" (such as those found near roadways and dusty industries), which are larger than
2.5 micrometers and smaller than 10 micrometers in diameter; and "fine particles" (such as those found in
smoke and haze), which are 2.5 micrometers in diameter and smaller.
The Clean Air Act requires EPA to set air quality standards to protect both public health and the public welfare
(e.g. crops and vegetation). Particle pollution affects both.
Particle pollution - especially fine particles - contains microscopic solids or liquid droplets that are so small that
they can get deep into the lungs and cause serious health problems. Numerous scientific studies have linked
particle pollution exposure to a variety of problems, including:
increased respiratory symptoms, such as irritation of the airways, coughing, or difficulty breathing, for example;
People with heart or lung diseases, children and older adults are the most likely to be affected by particle
- decreased lung function;
- aggravated asthma;
- development of chronic bronchitis;
- irregular heartbeat;
- nonfatal heart attacks; and
- premature death in people with heart or lung disease.
pollution exposure. However, even if you are healthy, you may experience temporary symptoms from exposure
to elevated levels of particle pollution. For more information about asthma, visit www.epa.gov/asthma.
Fine particles (PM2.5) are the major cause of reduced visibility (haze) in parts of the United States, including
many of our treasured national parks and wilderness areas. For more information about visibility, visit www.epa.
Particles can be carried over long distances by wind and then settle on ground or water. The effects of this
settling include: making lakes and streams acidic; changing the nutrient balance in coastal waters and large
river basins; depleting the nutrients in soil; damaging sensitive forests and farm crops; and affecting the
diversity of ecosystems. More information about the effects of particle pollution and acid rain.
Particle pollution can stain and damage stone and other materials, including culturally important objects such
as statues and monuments. More information about the effects of particle pollution and acid rain.