01515430

Component

An air quality study was recently conducted for the Gateway Cities (GC) portion of Los Angeles County as part of a health risk assessment. The GC region is composed of some 36 communities with a population of 2 million adjacent to the ports of Long Beach and Los Angeles and in the vicinity of the Interstate 710 freeway corridor. The study addressed current (2009) and projected future (2035) air quality of criteria pollutants (NOx, CO, SO2, PM10, PM2.5, and Pb) and air toxics (1-3-butadiene, benzene, hexavalent chromium, diesel particulate matter, and formaldehyde). In order to determine the relative contribution of mobile source emissions to air pollution, the study included all anthropogenic emission sources. Onroad vehicles emissions of criteria pollutants were estimated with the California’s EMFAC2011 model and a travel demand model, and were characterized as area source polygons approximating roadway links. For all other sources emissions of criteria pollutants, , and air toxics were taken from the South Coast Air Quality Management District’s 2008 Air Quality Management Plan emission inventory. Emissions of air toxics were derived by applying speciation factors to PM2.5 and TOG emissions. The CALPUFF air dispersion model was used to predict air concentrations at each of more than 1400 Census block group centroids. Meteorological inputs were prepared with the CALMET model. This fine spatial resolution of both emissions and modeling receptors allowed a more accurate estimate of the full range of air quality concentrations across the modeling domain than most previous studies. The results showed exceedances of NO2 and PM2.5 NAAQS at many block group centroids in 2009, with about two-thirds of NOx emissions and one-quarter of PM2.5 emissions, including road dust, from onroad vehicles. However, by 2035 the number of centroids in exceedance of NO¬2 and PM2.5 NAAQS were predicted to be reduced to 5 and 65, respectively, due to implementation of air quality improvement measures. Using California’s pollutant toxicity estimates, cancer health risk was dominated by diesel particulate matter with an average 2009 concentration of 4.0 µg/m3 (maximum = 15.1 µg/m3), falling 78% to 0.9 µg/m3 (maximum = 8.1 µg/m3) by 2035, despite an increase in heavy-duty VMT of 65%. In 2009 onroad vehicles risk contribute about 58%, reduced to 54% in 2035.

This paper was sponsored by TRB committee ADC20 Transportation and Air Quality.

01503729

14-5355

English

19p

2014

Transportation Research Board 93rd Annual Meeting

Digital/other

Figures; Maps; References; Tables

Air quality; Air quality management; Poisons; Pollutants; Public health

Interstate 710; South Coast Air Quality Management District

Los Angeles County (California)

Environment; Highways; I15: Environment

Transportation Research Board Annual Meeting 2014 Paper #14-5355

TRIS, TRB, ATRI

Jan 27 2014 3:52PM