The characteristics and size of lung-depositing particles vary significantly between high and low pollution traffic environments

TUBE Project: Transport-Derived Ultrafines and the Brain Effects

“…While existing scientific information underlines the role of ambient air pollution in human population health, information related to the spatial differences in UFP concentrations and the characteristics of UFPs in different environments is scarce. For example, although recent studies have shown that traffic can emit significant amounts of extremely small particles (<30 nm) into the urban atmosphere [ 27 ], routine monitoring is currently not required by legislation in any of the EU member states. Moreover, although particle emission regulations limit the emission of many traffic modes with respect to solid particles larger than 23 nm, information regarding their atmospheric concentrations is incomplete or suboptimal.…”

“…The first results of studies on ambient aerosols were published by Salo et al [ 27 ]. Based on their experimental observations, particle size distribution and particle concentrations can differ significantly between the roadside environments of relatively clean and highly polluted cities, i.e., Helsinki and the Delhi area.…”

Reply on CC1

“…However, the impact of larger particles (>400 nm) to alveolar LDSA might be significant, for example a recent study on LDSA concentrations in polluted urban environment in India observed high LDSA contribution from relatively large accumulation mode particles although the experiment was conducted in close proximity of traffic (Salo et al, 2021a) and in mining environment the mineral dust and other pollutants being typically in larger particle sizes can also contribute to the LDSA concentrations (Salo et al, 2021b). In HMA, the impact of >400 nm might also be significant during PM2.5 long-range transport episodes or when there are many particles from very low-quality residential burning in detached housing areas (Pirjola et al, 2017).…”

“…Since the vehicular combustion emits smaller particles which elevate the LDSA concentration but meanwhile do not substantially influence the value of PM2.5 (e.g. Salo et al, 2021a); therefore, LDSA/PM2.5 has a diurnal pattern similar to the LDSA concentrations which peaks in the morning rush hour during workdays.…”

“…nm) might be significant due to regional background in very polluted cities (e.g. Delhi, Salo et al, 2021a) or very low-quality residential burning in detached housing areas (e.g. HMA, Pirjola et al, 2017).…”