Health and Environment Linked for Information Exchange, Atlanta (HELIX-Atlanta).

Linkage of Environmental and Health Data

Two sources of environmental data for HELIX-ATLANTA:
  1. U.S. EPA Air Quality System (AQS): Daily PM2.5 measurements
  2. NASA EOS Data Gateway: MODIS Aerosol Optical Depth (AOD), used to estimate ground-level PM2.5 concentrations.

Processing, Linkage and Data Exchange

  • The environmental data (PM2.5) are linked to the health data (acute asthma office visit data) provided by Kaiser Permanente of Georgia (KP-GA).
  • The linked data that includes individual health information are sent from NASA to KP-GA for further analysis.
  • The linked data are aggregated into surfaces of 10 km by 10 km resolution that will protect the privacy and confidentiality of KP-GA health members.
  • The aggregated data set are sent back to the CDC and published for the public.

The data and model components and linkages for the respiratory health activity within HELIX-Atlanta. Environmental data were provided by EPA and NASA. These were QCd and merged to provide daily spatial maps of PM2.5. Health data (acute asthma office visits) from Kaiser Permanente-Georgia, obtained via a Business Associate Agreement, were linked with the environmental data. The complete linked data set is protected health information and may only be shared with the HMO. Spatially aggregated data sets are shared with CDC and the general community.
HMO Members
-84.207 99.200 1 Child M 200301
-84.802 99.359 2 Adult M 200301
-83.798 99.993 4 Child F 200301
Visit counts by grid cell
Date Cell PM2.5 FC MC FA MA
200301 1 21.74 1 0 2 0
200301 2 12.79 0 0 0 0
200301 3 12.21 0 1 0 1
Acute asthma office visits
1811 Child -84.179 99.118 F 1/1/2003
54767 Adult -84.625 99.802 F 1/1/2003
84580 Adult -84.679 99.691 F 1/1/2003

The tables above illustrates data linkage of environmental (PM2.5) and health (asthma) for the HELIX-Atlanta study. The upper left table shows simulated residence locations for HMO members for which data were available for the study, and the lower left lists acute asthma office visits by date. The table on the right provides counts of these visits by day for each 10 km grid cell within the study area. These data are simulated; actual linked data sets constitute protected health information. F=female, M=male, C=child, A=adult.

Epidemiological findings for PM2.5 and asthma:
  • Even with small numbers of acute asthma visits, statistical significance can be detected with Poisson Generalized Linear Model.
  • There appears to be a relationship between PM2.5 and acute asthma visits.
  • Gender and age-group differences were found in relationships between PM2.5 and acute asthma visits.
  • Findings vary by grid cell and by county in significance, direction of association, and lags.

Additional Information

National EPHT Program (
Dale Quattrochi (
Doug Rickman (
Solomon Pollard(
Technical Contact: Dr. Dale Quattroci (
Responsible Official: Dr. James L. Smoot (
Page Curator: Diane Samuelson (