Individual and population intake fractions of diesel particulate matter (DPM) in bus stop microenvironments

Diesel particulate matter (DPM) is associated with adverse human health effects. This study aims to investigate the relationship between DPM exposure and emissions by estimating the individual intake fraction (iF_i) and population intake fraction (iF_p) of DPM. Daily average concentrations of particulate matter at two bus stops during rush hours were measured, and then they were apportioned to DPM due to heavy-duty diesel bus emissions using Chemical Mass Balance Model. The DPM emissions of diesel buses for different driving conditions (idling, creeping and traveling) were estimated on the basis of field observations and published emission factors. The median iF_i of DPM was 0.67 and 1.39 per million for commuters standing at the bus stop and pedestrians/cyclists passing through the bus stop during rush hours, respectively. The median iF_p of DPM was 94 per million. Estimations of iF_i and iF_p of DPM are potentially significant for exposure assessment and risk management. - Highlights: • Methods to estimate the individual and population intake fraction in bus stop microenvironments were established. • Source apportionment was performed to estimate the DPM due to diesel bus emissions in bus stop microenvironments. • The DPM emission in bus stop microenvironments rather than in the entire urban area was considered. • The movement of people and their exposure duration were introduced in the estimation of population intake fraction. - This work established a method to estimate the individual and population intake fraction in transportation microenvironments on the basis of PM source apportionment.