Grids were matched to monitoring sites and a filter applied to created baseline concentrations of PM2.5.
Briefly, meteorological conditions and criteria pollutant emissions are input into CMAQ, which simulates atmospheric processes and estimates gridded concentrations of ambient air pollutants; grids were matched to monitoring sites and a filter applied to created baseline concentrations of PM2.5 species (Hogrefe et al. 2009).
Since the EPA does not collect data daily at all locations, we allowed subjects to be matched to the nearest monitor with available data for that day.
sICAM-1 and sVCAM-1 were measured from 1999-2008 and matched to air pollution monitoring for fine particulate matter (PM2.5) black carbon, and sulfates (SO4).
Demographics of the NBDPS controls and CHD defect groupings providing residential address information and eligible to be matched to the closest air monitor for each pollutant are presented in Table 1.
Each geocoded address during weeks 2 8 of pregnancy was matched to the closest air monitor for each pollutant, with > 50% of the data available using ArcGISv10 (ESRI, Redlands, CA) and monitor locations obtained from U.S. EPA's Air Quality System (U.S. EPA 2013).
Pollutant monitors were matched to U.S. census tracts, which are geographic units representing small subdivisions of a county and are the smallest spatial unit for which demographic variables of interest were available.
Two chlorpyrifos and two diazinon monitoring locations matched to meteorologic stations nearby (within 3 miles), whereas the two other chlorpyrifos and two other diazinon monitoring locations matched to stations farther away (9 and 15 miles).
The difference between these planes should not matter given the high accuracy with which the directions of hand movements can be matched to directions presented on the monitor [16].
