Linking in-vehicle ultrafine particle exposures to on-road concentrations

Abstract

For traffic-related pollutants like ultrafine particles (UFP, Dp < 100 nm), a significant fraction of overall exposure occurs within or close to the transit microenvironment. Therefore, understanding exposure to these pollutants in such microenvironments is crucial to accurately assessing overall UFP exposure. The aim of this study was to develop models for predicting in-cabin UFP concentrations if roadway concentrations are known, taking into account vehicle characteristics, ventilation settings, driving conditions and air exchange rates (AER). Particle concentrations and AER were measured in 43 and 73 vehicles, respectively, under various ventilation settings and driving speeds. Multiple linear regression (MLR) and generalized estimating equation (GEE) regression models were used to identify and quantify the factors that determine inside-to-outside (I/O) UFP ratios and AERs across a full range of vehicle types and ages. AER was the most significant determinant of UFP I/O ratios, and was strongly influenced by ventilation setting (recirculation or outside air intake). Inclusion of ventilation fan speed, vehicle age or mileage, and driving speed explained greater than 79% of the variability in measured UFP I/O ratios.

Personal day-time exposure to ultrafine particles in different microenvironments

“…Personal PNC fluctuated greatly within traffic related microenvironments. Large differences when driving may result from car ventilation settings (Hudda et al, 2012), traffic conditions (congested condition, busy or empty road and the emissions of nearby cars) and road/street characteristics (Dons et al, 2013;Scungio et al, 2013). In contrast, PNC were very steady when indoors without any activities.…”

Outdoor and indoor UFP in primary schools across Barcelona

“…The daily cycle of N in urban environments has been observed to be highly influenced by traffic emissions. Numerous studies have shown that N on or in the vicinity of roadways is frequently almost one order of magnitude higher than ambient levels (Westerdahl et al, 2005;Hudda et al, 2012). Daily N cycles showing new particles formation by nucleation coinciding with high solar radiation in warm climate regions are widely documented (e.g.…”

Fast response sequential measurements and modelling of nanoparticles inside and outside a car cabin

“…Therefore, it can be concluded that despite good performance for averaged PNCs, the 463 model might be further improved by using appropriate A E values at each time step. Existing 464 quantitative models, such as those proposed by Hudda et al (2012) can be implemented in 465…”