The Neighborhood Scale Variability of Airborne Particulates

Abstract

Airborne particulates play a central role in both the earth's radiation balance and as a trigger for a wide range of health impacts. Air quality monitors are placed in networks across many cities glo-bally. Typically these provide at best a few recording locations per city. However, large spatial va-riability occurs on the neighborhood scale. This study sets out to comprehensively characterize a full size distribution from 0.25 -32 μm of airborne particulates on a fine spatial scale (meters). The data are gathered on a near daily basis over the month of May, 2014 in a 100 km 2 area en-compassing parts of Richardson, and Garland, TX. Wind direction was determined to be the domi-nant factor in classifying the data. The highest mean PM2.5 concentration was 14.1 ± 5.7 μg • m −3 corresponding to periods when the wind was out of the south. The lowest PM2.5 concentrations were observed after several consecutive days of rainfall. The rainfall was found to not only " cleanse " the air, leaving a mean PM2.5 concentration as low as 3.0 ± 0.5 μg • m −3 , but also leave the region with a more uniform PM2.5 concentration. Variograms were used to determine an appro-priate spatial scale for future sensor placement to provide measurements on a neighborhood scale and found that the spatial scales varied, depending on the synoptic weather pattern, from 0.8 km to 5.2 km, with a typical length scale of 1.6 km.