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Chronic Disease and the Environment

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Chronic Disease and the Environment

Limitations and Inappropriate Uses of AQS Data with the BRFSS

Although the AQS data can be used with BRFSS data to compare measures of environmental risk factors and chronic disease, important restrictions affect how the data should be used and interpreted. These restrictions include, but are not limited to, the following:

  • Analysis levels and temporality. Because the environmental data from the AQS used in this project were collected during the data years 2001–2006 and reported at the metropolitan area-level, they should only be used in conjunction with 2001–2006 BRFSS data provided via the Chronic Disease and the Environment project. These data have been re-weighted for metropolitan area-level analysis.
  • Exposure assessment. The AQI only approximates the level of pollution in a metropolitan area. Because it does not measure the extent to which people are exposed to these pollutants, AQI values can not be used to identify exposures and risks for specific individuals. Individuals within a metropolitan area may have substantially higher or lower pollution exposures due to a number of factors, including variations in individual activity patterns and physical location within a metropolitan area. The AQI values for a metropolitan area should not be linked to an individual respondent from the BRFSS.
  • Comprehensiveness. The AQS is not an indicator of overall air quality. The criteria pollutants included in the AQS are only a subset of the 188 pollutants listed in the Clean Air Act. In addition, for certain chemicals, ingestion or dermal exposure, as well as indoor sources of inhalation exposure, may contribute substantially to the total exposures of concern. The AQS assessment does not address these other means of exposure.
  • Quality. Because air pollution measured in the vicinity of a particular source may not be representative of the prevailing air quality of a county or urban area, AQS data may not accurately reflect the air quality of an entire metropolitan area, particularly in geographically large metropolitan areas with few AQS monitors. Also, the BRFSS can only provide annual measures for health risks, necessitating the use of annual summary statistics for air quality measures.
  • Summary measures. A metropolitan area’s daily AQI value is based on the highest pollutant-specific AQI value for that day. It thus provides information about the predominant pollutant on a given day and some information about the levels of the other pollutants (i.e., they each had an individual AQI less than the daily AQI). However, the AQI does not fully characterize the contributions of the other criteria pollutants to air quality or take into account possible adverse effects associated with combinations of pollutants.

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Page last reviewed: 12/10/2008
Page last updated: 12/10/2008

United States Department of Health and Human Services
Centers for Disease Control and Prevention
National Center for Chronic Disease Prevention and Health Promotion
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