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Health Impacts of Fine Particles in Air

NEW Mortality benefit estimates associated with reducing PM2.5 are now available for Coronary Artery Disease as well as deaths from all causes.

Air pollution is a leading environmental threat to human health. Particles in the air such as dust, dirt, soot, and smoke are one kind of air pollution that is known to cause health problems. Particles in the air come from many different sources. The composition of these particles can vary based on location, season, and whether they are from primary or secondary sources. Primary sources give off particulate matter directly. For example, forest fires, road dust, electrical power plants, industrial processes, and cars and trucks are primary sources. Secondary sources give off gases that react with sunlight and water in the air to form particles. Coal-fired power plants and exhaust from cars and trucks are common secondary sources.

Size comparison of PM2.5 to a human hair and grain of sand.

Click to enlarge

Very small particles that are less than 2.5 micrometers in width are known as fine particulate matter or PM2.5. These particles are less than 1/30 the width of a human hair. Fine particulates can play a role in causing serious illnesses and death because they are small enough to be inhaled deep into the lungs. Once fine particles are in the lungs, they can affect the heart, blood vessels, and lungs.

People exposed to fine particles over a long period of time have more heart and lung problems than people who are not breathing this kind of air pollution. Lowering PM levels would prevent deaths, mostly from heart attacks and heart disease. Studies have shown a 15% decrease in the risk of heart disease deaths with every PM2.5 decrease of 10ug/m3 (micrograms per cubic meter). Read more about the health impacts of PM2.5.

Coronary artery disease (CAD, also known as coronary heart disease or ischemic heart disease) is the most common type of heart disease in the United States. While CAD is largely related to lifestyle habits such as poor diet, lack of physical activity, and smoking, it is also the most common heart problem related to exposure to fine particles over a long period of time. CAD occurs when a substance called plaque builds up in the arteries that supply blood to the heart. When this happens, your arteries can narrow over time. Once your arteries begin to narrow, you can experience chest pains, an irregular heartbeat, a weakened heart, or a heart attack. Scientists are still performing research to figure out exactly why fine particle exposure is related to ischemic heart disease. Read more about coronary artery disease.

Some communities may be more at risk for heart and lung problems related to air pollution because of other health risk factors including low socioeconomic status, environmental issues, and high numbers of people with poor lifestyle habits. Examples include:

Cars in heavy traffic putting out exhaust fumes.
  • high rates of poverty
  • high numbers of people without health insurance
  • high obesity and diabetes prevalence
  • high rates of smoking
  • higher amounts of car and truck exhaust due to greater population density
  • factory emissions
  • high percentage of young children and older adults over the age of 65 years

These risk factors are associated with more heart and lung problems, hospital visits, and deaths in areas with high amounts of air pollution. Information about risk factors can be used together with air pollution data to help public health officials plan and deliver the right help to communities.

How the Tracking Network data was developed

PM2.5 Prevalence Map

Click to enlarge

CDC's Tracking Network uses methods developed by the U.S. Environmental Protection Agency (EPA) and others to estimate how lowering air pollution levels can affect health. The EPA's Benefits Mapping and Analysis Program (BenMAP) is a geographic information system-based program that helps CDC calculate health impacts of air pollution across regions of the country. BenMAP estimates changes in the number of illnesses and deaths that could occur in a population if air pollution levels were reduced by a specified amount.

CDC uses an approach similar to BenMAP with modeled air data for fine particulates, death data from CDC's National Center for Health Statistics, population data from the U.S. Census Bureau, and information about the relationship between change in air pollution and how that influences health effects from scientific literature. This method:

  • uses air quality modeled data to estimate current or baseline fine particulate levels,
  • outlines comparison air quality conditions,
  • estimates the potential change in air pollution levels as the difference between the current level and the comparison level for each county,
  • estimates the number of lives saved by reducing fine particulates (i.e., concentration-response function), and
  • estimates the positive health impact that could be achieved with a change in outdoor air quality.
  • estimates the health improvements that could be achieved with better outdoor air quality.

You can read more about the formula for these estimates here.

Uses for Tracking Network Fine Particle Air Pollution data

Smoke coming off a burning hillside, near a residential development. The Tracking Network presents realistic estimates for health improvement by linking air quality data and health data together. The indicator presented here is Mortality Benefits associated with Reducing PM2.5 Concentration Levels. These data summarize the estimated number of deaths prevented and percent change in deaths associated with lowering PM2.5 concentration levels. The count and rate measures within this indicator can help identify areas where interventions to reduce air pollution could result in meaningful health improvements. The data about fine particle air pollution's effect on health can help policymakers or public health officials make decisions about improving air quality, which can reduce illness and death in their communities.

The health effects of air pollution are affected by social, demographic, and economic factors. Factors that may increase vulnerability to health effects include income, race and ethnicity, health insurance, and age. The Tracking Network lets the user sort results by categories of county-level social variables such as:

  • percentage of population in poverty,
  • percentage of adult smokers,
  • percentage of obese adults (body mass index (BMI) ≥30 kg/m2),
  • percentage of adults who report no leisure time physical activity,
  • diabetes prevalence,
  • percentage of population under 65 years who are uninsured,
  • percentage of population that are over 65 years, and
  • population density.

Data available on the Tracking Network can be used to estimate the number of all-cause deaths and the number of deaths from Coronary Artery Disease (CAD) prevented in a county, state, or the nation assuming certain reductions in PM2.5 concentrations,

For example, according to 2009 data available on the Tracking Network, a 10% reduction in PM2.5 could prevent:

  • more than 400 deaths per year in a highly populated county, like Los Angeles County;
  • about 1,500 deaths every year in California; and
  • over 13,000 deaths across the nation.

Additional resources about health impact assessments are available here.

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