TITLE:
The Neighborhood Scale Variability of Airborne Particulates
AUTHORS:
William A. Harrison, David Lary, Brian Nathan, Alec G. Moore
KEYWORDS:
PM2.5, Variograms, Neighborhood Scale, Spatial Length
JOURNAL NAME:
Journal of Environmental Protection,
Vol.6 No.5,
May
11,
2015
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
glob-ally. Typically these provide at best a few recording locations per city.
However, large spatial var-iability 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
km2 area encompassing parts of Richardson, and Garland, TX. Wind direction was
determined to be the dominant 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 appropriate 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.