Use of Satellite Remote Sensing for Public Health Applications: The HELIX-Atlanta Experience

Transcription

1 Use of Satellite Remote Sensing for Public Health Applications: The HELIX-Atlanta Experience Bill Crosson Mohammad Al-Hamdan, Maury Estes, Ashutosh Limaye, Dale Quattrochi, Doug Rickman NASA/MSFC/NSSTC Partners: Centers for Disease Control and Prevention Kaiser-Permanente Georgia U.S. Environmental Protection Agency Georgia Environmental Protection Division Georgia Division of Public Health Emory University Georgia Institute of Technology

2 HELIX-Atlanta Overview Health and Environment Linked for Information Exchange in Atlanta (HELIX-Atlanta) was developed to support state and local environmental public health tracking (EPHT) programs to implement data linking demonstration projects. NASA/MSFC and CDC are partners in linking environmental and health data to enhance public health surveillance.

3 HELIX-Atlanta Respiratory Health Team RH Team Pilot Data Linkage Project: Link environmental data from the MODIS sensor related to ground-level fine particulate matter (PM 2.5 ) with health data related to asthma Goal: Produce and share information on methods useful for integrating and analyzing data on asthma and PM 2.5 for environmental public health surveillance. Environmental Hazard Measure: Daily PM 2.5 Public Health Measure: Daily acute asthma office visits to Kaiser Permanente-GA medical facilities Time period: Domain: 5-county metropolitan Atlanta

4 Sources of PM 2.5 data: EPA AQS EPA Air Quality System (AQS) ground measurements National network of air pollution monitors Concentrated in urban areas, fewer monitors in rural areas Time intervals range from 1 hr to 6 days (daily meas. every 6 th day)

5 Quality Control of AQS PM 2.5 data Adapted from NSSTC CHARM rain gauge network Eliminates anomalous measurements Applied to all daily AQS PM 2.5 measurements before spatial surfaces are built PM 2.5 Concentration High : 50 µg/m 3 Low : 0 µg/m 3 EPA sites Before After Suspicious value

6 Spatial surfacing - AQS PM 2.5 data Two algorithms examined: 1 st degree recursive B- spline in x- and y directions Inverse Distance Weighting Daily surfaces created on a 10x10 km grid Variable number of daily measurements available PM 2.5 Concentration High : 50 µg/m 3 Low : 0 µg/m 3 EPA sites Data-rich day

7 Sources of PM 2.5 data: MODIS MODIS Aerosol Optical Depth (AOD) Provided on a 10x10 km grid Available twice per day (Terra ~10:30 AM, Aqua ~1:30 PM) Clear-sky coverage only Available since spring 2000 Used in NOAA/EPA Air Quality Forecast Initiative to produce air quality forecasts for northeastern US; forecasts for entire US in 2009

8 MODIS AOD - PM 2.5 Relationship micrograms/m /1/2002 2/1/2002 PM 2.5 and MODIS AOD Mean PM 2.5 Mean MODIS AOD 3/1/2002 4/1/2002 5/1/2002 6/1/2002 7/1/ /1/2002 Date 9/1/ /1/ /1/ /1/ MODIS AOD Mean PM 2.5 PM 2.5 and MODIS AOD Mean MODIS AOD Daily 5-site means of observed PM 2.5 and MODIS AOD MODIS data not available every day due to cloud cover MODIS AOD follows seasonal patterns of PM 2.5 but not the day-to-day variability in fall and winter micrograms/m MODIS AOD /1/2003 2/1/2003 3/1/2003 4/1/2003 5/1/2003 6/1/2003 7/1/2003 8/1/2003 Date 9/1/ /1/ /1/ /1/2003

9 PM 2.5 MODIS AOD Correlations April - September MODIS-Terra MODIS-Aqua > > > > July-September only Correlations between PM 2.5 and MODIS AOD are generally high (> 0.55) for the warm season.

10 PM2.5 (micrograms/m 3 ) Observed (AQS) and Predicted PM 2.5 South Dekalb 31-day mean Observed PM day mean MODIS-Estimated PM 2.5 April 2000 Dec /1/00 10/1/00 4/1/01 10/1/01 4/1/02 10/1/02 4/1/03 10/1/03 Date 40 MODIS-based predictions follow seasonal PM 2.5 patterns MODIS AOD is nearly constant in fall and winter, while observed PM 2.5 is not. Some major events are not captured by MODIS estimates. PM2.5 (micrograms/m 3 ) Doraville 31-day mean Observed PM day mean MODIS-Estimated PM /1/00 10/1/00 4/1/01 10/1/01 4/1/02 10/1/02 4/1/03 10/1/03 Date

11 PM 2.5 Estimated from MODIS-Terra PM2.5 Value Miles June 24, 2003

12 Merging MODIS and AQS PM 2.5 Data Merged MODIS Only 65 µg/m 3 0 µg/m 3 AQS only

13 Cross-Validation a.k.a. bootstrapping or omit-one analysis Objective: Estimate errors associated with daily spatial surfaces Procedure: Omitting one observation, create surface using N-1 observations Compare value of surface at location of omitted observation with the observed value Repeat for all observations Calculate error statistics by day or site

14 Cross-Validation Comparison B-Spline and IDW Surfacing Techniques AQS only Data Source Merged AQS-MODIS Root Mean Square Error in PM 2.5 estimates B-Spline IDW Use of MODIS data decreases RMS errors by 12% using B- Spline surfacing and 40% using IDW. Use of IDW surfacing decreases RMS errors by 15% using AQS-only data and 42% using merged MODIS-AQS data.

15 Linkage of Environmental and Health Data Data Linkage Outputs Visit rates by grid cell (visits/1000 members) Visits Members Rates Date Cell ---- Lat/Lon ---- FC MC FA MA Tot FC MC FA MA Tot FC MC FA MA Tot Linked data products have been developed for various spatial (10, 25, 50 km) and temporal (daily, weekly, monthly) aggregation levels. These data tables have been converted to spatial surfaces for visual comparison to PM 2.5 surfaces.

16 Public Health Surveillance Asthma vs. PM 2.5 Monthly Value Mean PM 2.5 (ug/m 3 ) 30 0 January 2002 Monthly Asthma Value Visits Rate (Per 10,000) 80 0

17 MODIS Limitations Poor correlations between ground-level PM 2.5 and MODIS AOD in the cold season MODIS AOD does NOT provide aerosol speciation that may be critical for evaluating health outcomes MODIS AOD does NOT provide vertical profile information that could be used to improve PM 2.5 estimation algorithms

18 NPOESS Era Aerosol Sensors Visible/Infrared Imager/Radiometer Suite (VIIRS on NPOESS) Aerosol optical thickness Particle size Suspended matter VIIRS Aerosol Polarimetry Sensor (APS on Glory) Aerosol optical thickness Particle size (effective radius, effective variance for fine and coarse modes Shape (sphericity) Refractive index Single scatter albedo Speciation APS

19 Linking Environmental and Health Data NASA Terra and Aqua Aerosol Optical Depth NASA/MSFC Linkage Aggregation Local/State Health Dept. PM2.5 (ug/m 3 ) HELIX-Atlanta RH team NASA MODIS Gateway Environ. Hazard Data Figure (PM Day Mean Concentrations) of all PM2.5 B-Spline Surfaces of year 2003 Aggregated Linked Data Health Outcome Data (Asthma Doctor Visits) PM2.5 (ug/m 3 ) Ground-Based PM 2.5 Concentrations EPA Figure Day Mean of all PM2.5 B-Spline Surfaces of year 2003 CDC EPA Air Quality Systems (AQS)

20 RMSD (micrograms/m 3 ) Cross-Validation for B-Spline Surfaces Daily Error Statistics Bootstrap-Observed Day of Year 8 Time Series Rank Order RMSD (micrograms/m 3 ) Bootstrap-Observed Day of Year