Particulate dust emission factors from unpaved roads in the U.S.–Mexico border semi-arid region

Abstract

Unpaved road dust emissions in El Paso in Texas, Las Cruces in New Mexico and Ciudad Juárez in Mexico were measured using the Testing Re-entrained Aerosol Kinetic Emissions from Roads (TRAKER) system. PM10 (particles with diameter < 10 μm) emissions factors from unpaved roads in Ciudad Juárez, Mexico increased by a factor of five as compared to those measured in El Paso, TX and Las Cruces, NM. The highest emission factors were observed in spring. A strong exponential dependence of PM10 emissions factors on vehicle speed was observed in Ciudad Juárez, Mexico and El Paso, TX, whereas they remained constant in Las Cruces, NM reflecting differences in soil surface characteristics. The highest PM10 emissions in Las Cruces and Ciudad Juárez originated from the sideline tire, indicating the possible influence of accumulated loose soil and debris on the side of the unpaved roads. Overall, strong spatial and temporal variability of PM10 emission factors were computed in the Paso del Norte region, reflecting differences in road surface and vehicle traffic characteristics and further underscored the need for high spatiotemporal resolution of emission inventories to accurately identify the most susceptible unpaved roads and control their burden on particulate pollution.