The PM10 fraction of road dust in the UK and India: Characterization, source profiles and oxidative potential

Most studies of road dust composition have sampled a very wide range of particle sizes, but from the perspective of respiratory exposure to resuspended dusts, it is the PM<inf>10</inf> fraction which is of most importance. The PM<inf>10</inf> fraction of road dust samples was collected at two sites in Birmingham, UK (major highway and road tunnel) and one site in New Delhi, India. Dust loadings were found to be much higher for New Delhi compared to Birmingham, while concentrations of several species were much higher in the case of Birmingham. Detailed chemical source profiles were prepared for both cities and previously generated empirical factors for source attribution to brake wear, tyre wear, and crustal dust were successfully applied to the UK sites. However, 100% of the mass for the Indian site could not be accounted for using these factors. This study highlights the need for generation of local empirical estimation factors for non-exhaust vehicle emissions. A limited number of bulk road dust and brake pad samples were also characterized. Oxidative potential (OP) was also determined for a limited number of PM<inf>10</inf> and bulk road dust samples, and Cu was found to be a factor significantly associated with OP in PM<inf>10</inf> and bulk road dust.