MODELING SPATIOTEMPORAL VARIABILITY OF INTRA-URBAN AIR CONTAMINANTS IN THE DETROIT AIRSHED: A PRAGMATIC APPROACH
This study combined a three-year air contaminant time series from the Michigan Air Sampling Network (MASN) with spatially detailed data sets for two two-week periods in September 2008 and June 2009 to produce monthly contaminant concentration maps across the city of Detroit, Michigan, from January 2008 through December 2010. Two geochemical analytes, NO2 and total BTEX, as well as two particulate matter size fractions, PM2.5 and PM10 were investigated. The September 2008 and June 2009 data sets were modeled using ordinary kriging to produce high spatial density concentration maps with 300m by 300m resolution across the city. A weighted average was applied to these maps to interpolate monthly concentration estimates between September 2008 and August 2009. Temporal variability was then incorporated by adjusting the weighted average spatial maps using a monthly average bulk shift derived from MASN time series measurements. The resulting maps incorporate seasonal trends while preserving neighborhood scale spatial variation. Results are being applied in a larger study designed to assess the relationship between adverse birth outcomes and air pollution in the city of Detroit.