Fields in the 'sites' datasets containing the monitoring site information for PM10 and PM2.5 ---------------------------------------------------------- siteID: unique text string identifying each site - equivalent to 'state-county-site' ID from EPA AQS siteNumber: unique (and arbitrary) number identifying each monitoring site network: character string identifying the monitoring network that the monitoring site belongs to. CMSA: character identifier of the Metropolitan Statistical Area (MSA) that the monitoring location is within. FIPS: two-digit state and three-digit county FIPS code for monitoring site lat: latitude of the monitoring site in decimal degrees lon: longitude of the monitoring site in decimal degrees landUse: land use at the monitoring site from USEPA AQS objective1: primary monitoring objective of the monitoring site from USEPA AQS objective2: secondary monitoring objective of the monitoring site from USEPA AQS locationSetting: location setting of the monitoring site from USEPA AQS albersX: the projected coordinate of the monitoring site (using the Albers Equal Area Conic USGS projection) in the east/west direction in thousands of kilometers (megameters) albersY: the projected coordinate of the monitoring site (using the Albers Equal Area Conic USGS projection) in the north/south direction in thousands of kilometers (megameters) cvSet: the cross-validation set to which the monitoring site belongs; 0 is states outside our prediction area, 10 is the fully held-out test set and 1-9 are validation sets popDensityBG: population density of the block group that the monitoring site is within from 1990 US Census popDensityTract: population density of the tract that the monitoring site is within from 1990 US Census popDensityCty: population density of the county that the monitoring site is within from 1990 US Census logDist1: log transformed distance from the monitoring site to the nearest road of class A1 logDist2: log transformed distance from the monitoring site to the nearest road of class A2 logDist3: log transformed distance from the monitoring site to the nearest road of class A3 urban: percentage of urban land use within 1 km of the monitoring site. elevation: elevation above sea level of the monitoring site at 30 m resolution. logPointEmit1km10,logPointEmit1km25: sum of the point-source PM10 or PM2.5 emissions within a radius of 1 km around the monitoring site logPointEmit10km10,logPointEmit10km25: sum of the point-source PM10 or PM2.5 emissions within a radius of 10 km around the monitoring site Fields in the 'monthly' datasets containing the monthly observations for PM10 and PM2.5 -------------------------------------------------------------- siteID: unique text string identifying each site - equivalent to 'state-county-site' ID from EPA AQS siteNumber: unique (and arbitrary) number identifying each monitoring site albersX: the projected coordinate of the monitoring site (using the Albers Equal Area Conic USGS projection) in the east/west direction in thousands of kilometers (megameters) albersY: the projected coordinate of the monitoring site (using the Albers Equal Area Conic USGS projection) in the north/south direction in thousands of kilometers (megameters) cvSet: the cross-validation set to which the monitoring site belongs; 0 is states outside our prediction area, 10 is the fully held-out test set and 1-9 are validation sets monthID: unique month identifier with 1=January 1985 and 216=December 2002 season: season in which the month falls: winter [Dec,Jan,Feb], spring [Mar,Apr,May], summer [Jun,Jul,Aug], fall [Sep,Oct,Nov]) monthOfYear: numeric variable indicating the month of the year in which the observation was taken (1-12) year: year in which the observation was taken nDays: the number of 24-hour average PM10 or PM2.5 values that were averaged to calculate the monthly average logPM10, logPM25: the log of the monthly average PM10 or PM2.5 mass concentration in micrograms per cubic meter of air at local conditions logAreaEmit10, logAreaEmit25: log of area-source emissions of PM10 or PM2.5 in short tons per year of the county that the monitoring site is within. stagnation: percentage of days in the month that met the definition of 'stagnant air day' from the NCDC Air Stagnation Index (http://lwf.ncdc.noaa.gov/oa/climate/research/stagnation/index.php) temp: monthly average air temperature, smoothed to each monitoring location, in tenths of degrees Fahrenheit. precip: monthly total precipitation, smoothed to each monitoring location, in hundredths of inches. pressure: monthly average barometric pressure, smoothed to each monitoring location, in millibars. windSpeed: monthly average wind speed at 10 m above ground level, smoothed to each monitoring location, in meters per second.