Comparisons of personal exposure to PM2.5 and CO by different commuting modes in Beijing, China

Epidemiological studies have shown that commuting in traffic is associated with adverse health effects. It is vital to investigate commuters' exposure to traffic-related air pollutants before considering potential health risks. However, there are relatively few publications considering commuters' personal exposure in China. We carried out a field investigation measuring commuters' personal exposure to particulate matter ≤2.5μm in aerodynamic diameter (PM2.5) and carbon monoxide (CO) by three commuting modes in Beijing. Both PM2.5 and CO personal concentrations and whole trip exposures were compared among the three commuting modes. After controlling confounding factors, we found that taxi commuters were exposed to lower concentrations of PM2.5 (31.64±20.77μg/m3) compared with bus commuters (42.40±23.36μg/m3) and cyclists (49.10±26.60μg/m3). By contrast, CO personal concentrations were significantly higher when commuting by taxi (5.21±1.52ppm) than by bus (2.41±0.99ppm) and bicycle (1.90±0.55ppm). However, when inhalation rates and trip duration were taken into consideration, cyclists experienced the highest whole trip exposures to both PM2.5 and CO (p