How the Tracking Network data was developed

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 is using 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.

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

Uses for Tracking Network Fine Particle Air Pollution data

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 PM_2.5 Concentration Levels. These data summarize the estimated number of deaths prevented and percent change in deaths associated with lowering PM_2.5 concentration levels. The count and rate measures 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:

• percent of population in poverty,
• percent of smokers,
• percent of population under 65 who are uninsured,
• percent of population that are non-whites,
• percent of population that are over 65, and
• population density.

Data available on the Tracking Network can be used to estimate the number of deaths prevented in a county, state, or the nation assuming certain reductions in PM_2.5. For example, according to 2006 data available on the Tracking Network, a 10% reduction in PM_2.5 could prevent:

• more than 400 deaths per year in a highly populated county, like Los Angeles County;
• more than about 1,400 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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