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Premature Mortality Due to Particulate Air Pollution in 239 American Cities

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This glossary provides an explanation of key terms reported in the MSA tables.

Each table provides summary information for the Metropolitan Statistical Area as a whole, and detailed information on PM-10 concentrations reported at individual monitoring stations within the MSA.

Tables for specific MSA's are from the May 1996 report by the Natural Resources Defense Council, BREATH-TAKING: Premature Mortality Due to Particulate Air Pollution in 239 American Cities. The report estimates that approximately 64,000 premature deaths from cardiopulmonary causes may be attributable to particulate air pollution each year.

PM-10 Concentration

This is the average of the annual mean concentration of PM-10 reported at all official monitoring stations within the MSA over the five year period, 1990 through 1994. PM-10 is particulate matter 10 microns or smaller in diameter. Concentrations are reported in ug/m³.

The rank compares the average annual mean PM-10 concentration of this MSA with the 239 MSAs for which we have data. A rank of 1 indicates the highest concentration.

Mortality Attributable to Particulate Air Pollution

The risk ratio presents the relative risk of premature mortality from cardiopulmonary causes for residents of this MSA compared to residents of the cleanest city studied.

The risk ratio was calculated by combining the MSA-specific monitoring data with a risk factor derived from a study of an American Cancer Society (ACS) cohort. (Pope, C. Arden, III, et al, "Particulate Air Pollution as a Predictor of Mortality in a Prospective Study of U.S. Adults," American Journal of Respiratory Critical Care Medicine, Vol. 151: 669-674, 1995.)

For each MSA, we present a point estimate of annual adult cardiopulmonary deaths attributable to air pollution, and a range. The point estimate is derived by applying the MSA-specific risk ratio to the actual number of annual deaths from cardiopulmonary causes in that MSA. The range estimates are derived from the upper and lower end of the confidence intervals for the risk ratio reported in the ACS study.

The rank compares the number of deaths attributable to air pollution to other MSAs, with a rank of 1 assigned to the city with most attributable deaths. The rate per 100,000 reflects the mortality attributable to particulate air pollution per 100,000 population, and the rank relative to other cities.


To put the air pollution attributable deaths into perspective, we provide data on the actual number of deaths for each MSA, from selected causes and for total mortality. All data are for 1989, and are derived from the Vital Statistics report of the National Center for Health Statistics. In addition to total mortality, we report MSA statistics for total adult cardiopulmonary deaths and for deaths from car accidents.


MSA population for 1980 is listed to provide a comparison with other MSAs of the same general size.

Counties Assigned to MSA

These are the counties, and in some cases cities, areas included in the MSA, as defined by the Office of Management and Budget for 1980, except for New England, where areas are New England County Metropolitan Areas. These were the definitions used in our analysis, for consistency with the mortality data. They are not necessarily the current definitions.

Monitoring Stations

All monitoring data is from the EPA AIRS database. We identify the location and report data from the official government monitoring networks, NAMS and SLAMS.

The monitoring stations are listed in order by state (if a multi-state MSA), county, and city, if available. The street address or location of each monitor is identified. Of special interest are monitors located at schools or other public buildings. Monitors were excluded if there were incomplete readings, or if the monitors were located in rural, forested areas.

The average annual mean PM-10 concentration is reported for each monitoring station, along with the number of years for which data were available. This data can be compared with the average annual mean reported for the MSA as a whole.

The peak 24-hour PM-10 concentration is the second highest 24-hour concentration during a year for which data was available for this monitoring station. The year of the peak reading is also identified.

PM-10 Hotspots

We identify as hotspots the top 50 monitoring stations in the U.S. that reported the highest average annual mean concentrations of PM-10 for the period 1990-1994, and the top 50 monitoring stations that reported the second highest 24-hour PM-10 concentration in 1994.

PM-10 Standards

The Notes provide reference levels of annual mean and 24-hour PM-10 concentrations to compare with the values reported for the MSA and for each monitoring station.

The National Ambient Air Quality Standards are the concentration levels established by U.S. EPA in 1987. EPA is now considering revisions to the standards to reflect the recent scientific evidence showing associations with premature death and illness at much lower concentrations.

The California Ambient Air Quality Standards are set at levels one-third the EPA standards.

The NRDC recommended standards represent the PM-10 levels that NRDC is advocating for the revised National Ambient Air Quality Standards. NRDC is also advocating that EPA establish new standards for fine particles. The PM-2.5 standards advocated by NRDC are 10 ug/m³ annual mean concentration, and 20 ug/m³ 24-hour average. These recommendations are based on levels at which adverse effects are reported in the epidemiological studies.

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