Quantification of Sources of Variability of Air Pollutant Exposure Concentrations among Selected Transportation Microenvironments

Abstract

<jats:p> The National Research Council has identified the lack of sufficient microenvironmental air pollution exposure data as a significant barrier to quantification of human exposure to air pollution. Transportation microenvironments, including pedestrian, transit bus, car, and bicycle, can be associated with higher exposure concentrations than many other microenvironments. Data are lacking that provide a systematic basis for comparing exposure concentrations in these transportation modes that account for key sources of variability, such as time of day, season, and types of location along a route such as bus stops and intersections. The objectives of this work are: to quantify and compare particulate matter (PM<jats:sub>2.5</jats:sub>), CO, and O<jats:sub>3</jats:sub> exposure concentrations in selected active and passive transportation microenvironments; and to quantify the effect of season, time of day, and location with respect to variability in transportation mode exposure concentrations. Measurements were made with an instrumented backpack and were repeated for multiple days in each season to account for the effect of inter-run variability. Results include mean trends, spatial variability, and contribution to variance. Pedestrian and cycle mode exposure concentrations were approximately similar to each other and were substantially higher than for bus and car cabins for both PM<jats:sub>2.5</jats:sub> and O<jats:sub>3</jats:sub>. Based on over 30 days of field measurements conducted over three seasons and for two times of day on weekdays, transportation mode and season were the largest contributors to variability in exposure for PM<jats:sub>2.5</jats:sub> and O<jats:sub>3</jats:sub>, whereas location type alone and in combination with transport mode helped explain variability in CO exposures. </jats:p>

Spatial-temporal distribution characteristics and traceability analysis of NOx emission from vehicles based on real-time automatic vehicle identification data in Guangzhou, China

“…The Bulletin of China's Ecological and Environmental Conditions 2022 [1] shows that the proportion of heavily polluted days with O3 as the main pollutant increased from 16.9% to 47.9% between 2015 and 2022. Epidemiologic studies have shown that long-term exposure of humans to high concentrations of O3 pollution can lead to asthma, lung cancer and other diseases [2,3]. Therefore, the control of O3 emissions has become the focus of China's air pollution prevention and control.…”