Assessment of personal exposure to PM for multiple transportation modes.

• PM concentrations and inhalation doses in Guangzhou presented the following trend: shared bikes > buses > cars > subways. • The counts of particle size range of 0.25–0.5 µm were highest in all travel modes. • Travel by "cars CW" (i.e., with closed windows) effectively prevented PM infiltration from outside air. • PM concentrations on weekends with peaks usually observed in the morning, were higher than those on weekdays. Travelers are severely exposed to traffic-related particulate matter (PM). To assess the personal exposure to PM for multiple transportation modes, we conducted a study on particle concentrations, size fractions, and inhalation doses in Guangzhou, China. PM concentrations and inhalation doses showed the following trend: shared bikes > buses > cars > subways. PM 0.25-1 concentrations in subway accounted for 56%–63% of all size fractions, while PM 2.5-10 dominated PM 0.25-2.5 in other modes. The highest particle counts were observed in the size range of 0.25–0.5 µm. PM concentrations on weekends were higher than those on weekdays. Peak concentrations were usually recorded in the morning on weekends but in the evening during weekdays. Females had higher exposure risks than males for the same distance covered using shared bikes due to longer travel duration. These results can provide theoretical guides for travelers to reduce personal exposure and health risks associated with PM. [ABSTRACT FROM AUTHOR]