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EPA/Federal Highway Administration (FHWA) Near Road Collaboration Project: Las Vegas Near Road Study – MSAT Results
Citation:
Kimbrough, Sue, R. Baldauf, R. Shores, AND D. Whitaker. EPA/Federal Highway Administration (FHWA) Near Road Collaboration Project: Las Vegas Near Road Study – MSAT Results. To be Presented at CRC MSAT Workshop, Sacramento, CA, February 04 - 06, 2013.
Impact/Purpose:
The series of studies conducted as part of the National Near Road Study focused on the collection of criteria air pollutants and mobile source air toxics (MSATs). The six priority compounds of interest were diesel particulate matter, benzene, 1,3-butadiene, acrolein, acetaldehyde, and formaldehyde. One study in the series was conducted in Las Vegas, NV from mid-December 2008 to mid-December 2009. During this study continuous and integrated ambient air quality samples were collected. The volatile organic compound (VOC) and carbonyl measurements discussed herein were collected at four air monitoring stations located 100 meter (m) upwind, 20 m roadside, 100 m downwind, and 300 m downwind from Interstate15 (I-15). Specifically, this study was conducted, between the I-215 interchange and the Russell Road interchange. The premise of near-road studies is that MSAT concentrations are highest near the road with a spatial gradient change of concentrations as distance increases from the road. Results from the Las Vegas study indicated that MSAT concentrations were influenced by multiple sources including the target highway I-15, Las Vegas Boulevard (570 m east of 100 m downwind site), McCarran International Airport (700 m east of 100 m downwind site, and nearby parking lots (immediately south of the 100 m site). Higher concentrations of acetaldehyde were observed at the 100 m upwind site than at the 20 m roadside site for all wind conditions and downwind conditions. The median concentration of acetaldehyde at the 20 m roadside site and 100 m downwind site were 1.71 µg/m3 and 1.79 µg/m3 for all wind conditions, respectively. Under downwind conditions (winds from the west), the median concentration of acetaldehyde at the 20 m roadside site and 100 m downwind site was 2.01 and 2.06 µg/m3, respectively. Higher than expected concentrations were observed at the 100 m downwind site for benzene. The median concentration of benzene at the 20 m roadside site and 100 m downwind site was 0.52 µg/m3 and 0.85 µg/m3 for all wind conditions, respectively. Under downwind conditions (winds from the west), the median concentration of benzene at the 20 m roadside site and 100 m downwind site was 0.58 and 1.02 µg/m3, respectively. Median concentrations are higher at the site furthest from the roadway leading to the conclusion that nearby sources at this particular study location have influenced the results such that the typical spatial gradient change of concentrations is not well defined.
Description:
The series of studies conducted as part of the National Near Road Study focused on the collection of criteria air pollutants and mobile source air toxics (MSATs). The six priority compounds of interest were diesel particulate matter, benzene, 1,3-butadiene, acrolein, acetaldehyde, and formaldehyde. One study in the series was conducted in Las Vegas, NV from mid-December 2008 to mid-December 2009. During this study continuous and integrated ambient air quality samples were collected. The volatile organic compound (VOC) and carbonyl measurements discussed herein were collected at four air monitoring stations located 100 meter (m) upwind, 20 m roadside, 100 m downwind, and 300 m downwind from Interstate15 (I-15). Specifically, this study was conducted, between the I-215 interchange and the Russell Road interchange. The premise of near-road studies is that MSAT concentrations are highest near the road with a spatial gradient change of concentrations as distance increases from the road. Results from the Las Vegas study indicated that MSAT concentrations were influenced by multiple sources including the target highway I-15, Las Vegas Boulevard (570 m east of 100 m downwind site), McCarran International Airport (700 m east of 100 m downwind site, and nearby parking lots (immediately south of the 100 m site). Higher concentrations of acetaldehyde were observed at the 100 m upwind site than at the 20 m roadside site for all wind conditions and downwind conditions. The median concentration of acetaldehyde at the 20 m roadside site and 100 m downwind site were 1.71 µg/m3 and 1.79 µg/m3 for all wind conditions, respectively. Under downwind conditions (winds from the west), the median concentration of acetaldehyde at the 20 m roadside site and 100 m downwind site was 2.01 and 2.06 µg/m3, respectively. Higher than expected concentrations were observed at the 100 m downwind site for benzene. The median concentration of benzene at the 20 m roadside site and 100 m downwind site was 0.52 µg/m3 and 0.85 µg/m3 for all wind conditions, respectively. Under downwind conditions (winds from the west), the median concentration of benzene at the 20 m roadside site and 100 m downwind site was 0.58 and 1.02 µg/m3, respectively. Median concentrations are higher at the site furthest from the roadway leading to the conclusion that nearby sources at this particular study location have influenced the results such that the typical spatial gradient change of concentrations is not well defined.