Estimation of PM10 in the traffic-related atmosphere for three road types in Beijing and Guangzhou, China

The levels of roadside PM₁₀ in Beijing, China, were investigated in 2011 and 2012 on a seasonal basis to estimate the population exposure to particulates for three road types. The measurements of PM₁₀ were also conducted in the southern Chinese megacity of Guangzhou for comparison purposes. The results showed that roadside PM₁₀ in Beijing correlated strongly with the PM₁₀ background in the urban atmosphere. The levels of PM₁₀ in street canyons were markedly higher than those along the open roads and in crossroad areas because of limited ventilation. An elevation of PM₁₀ was observed in April, which was possibly due to the sand storms that frequently occur in the spring. Based on these observations, roadside PM₁₀ in Beijing could have multiple origins and was to some extent dispersiongoverned. In Guangzhou, the roadside PM₁₀ did not closely relate to the background values. The PM₁₀ pollution was greatly affected by local traffic conditions. The simulation of PM₁₀ for different road types was completed during the study period using the Motor Vehicle Emissions Factor Model (MOBILE6.2) as an emission model and the California Line Source Dispersion Model (CALINE4) and Operational Street Pollution Model (OSPM) as dispersion models. The MOBILE6.2/CALINE4 software package was demonstrated to be sufficient for the simulation of PM₁₀ in the open roads and crossroad areas in both Beijing and Guangzhou, and the simulation results of roadside PM₁₀ in the street canyons by the MOBILE6.2/OSPM package were in close agreement with those of the measurements.