Comparing on-road real-time simultaneous in-cabin and outdoor particulate and gaseous concentrations for a range of ventilation scenarios

Abstract

Advanced automobile technology, developed infrastructure, and changing economic markets have resulted in increasing commute times. Traffic is a major source of harmful pollutants and consequently daily peak exposures tend to occur near roadways or while traveling on them. The objective of this study was to measure simultaneous real-time particulate matter (particle numbers, lung-deposited surface area, PM2.5, particle number size distributions) and CO concentrations outside and in-cabin of an on-road car during regular commutes to and from work. Data was collected for different ventilation parameters (windows open or closed, fan on, AC on), whilst traveling along different road-types with varying traffic densities. Multiple predictor variables were examined using linear mixed-effects models. Ambient pollutants (NOx, PM2.5, CO) and meteorological variables (wind speed, temperature, relative humidity, dew point) explained 5–44% of outdoor pollutant variability, while the time spent travelling behind a bus was statistically significant for PM2.5, lung-deposited SA, and CO (adj-R2 values = 0.12, 0.10, 0.13). The geometric mean diameter (GMD) for outdoor aerosol was 34 nm. Larger cabin GMDs were observed when windows were closed compared to open (b = 4.3, p-value = <0.01). When windows were open, cabin total aerosol concentrations tracked those outdoors. With windows closed, the pollutants took longer to enter the vehicle cabin, but also longer to exit it. Concentrations of pollutants in cabin were influenced by outdoor concentrations, ambient temperature, and the window/ventilation parameters. As expected, particle number concentrations were impacted the most by changes to window position / ventilation, and PM2.5 the least. Car drivers can expect their highest exposures when driving with windows open or the fan on, and their lowest exposures during windows closed or the AC on. Final linear mixed-effects models could explain between 88–97% of cabin pollutant concentration variability. An individual may control their commuting exposure by applying dynamic behavior modification to adapt to changing pollutant scenarios.

Black Carbon and Particulate Matter Concentrations in Eastern Mediterranean Urban Conditions: An Assessment Based on Integrated Stationary and Mobile Observations

“…We verified that by comparing co-located measurements in-car and on-road [23]. This issue was also investigated in several previous studies focusing the indoor-to-outdoor relationship of aerosols [73][74][75][76][77][78][79][80][81][82][83][84]; here, indoor refers to "in-vehicle", whereas outdoor refers to "on-road". The studies agree on the fact that the indoor-to-outdoor ratio (I/O) of UFPs and concentrations is affected by the car speed and fan mode (low, medium, and full), as well as the type of air filter installed in the air-exchange system for the car cabin.…”

Personal Exposure to PM2.5 in the Megacity of Mexico: A Multi-Mode Transport Study

“…However, consistent with our results, cyclists exhibited the highest exposure among the transport modes studied. By contrast, exposure concentrations for CC and HEC when travelling with open windows in our study are around 50% lower than those observed in St. Louis, MO, USA, by Leavey et al [25].…”

“…However, the link between plumes and traffic density could be improved significantly by performing vehicle counts or conducting visual recording. Leavey et al [25] observed that concentrations of PM 2.5 in-cabin followed closely with outdoor levels when travelling with open windows, which may explain the peak observed for the CC. Our results contrast with observations made in California by Quiros et al [17], who reported an increase in the levels of ultrafine particles but not in PM 2.5 when walking close to a diesel bus during the accelerating phase after a complete stop.…”

Chemistry and sources of PM2.5 and volatile organic compounds breathed inside urban commuting and tourist buses

“…Given the sometimes radical differences in atmospheric microenvironments experienced by city travellers using different transport modes, many of these publications have turned their attention specifically to air quality found inside moving vehicles (e.g. Alameddine et al, 2016;Fruin et al, 2011;Hudda et al, , 2012Hudda and Fruin 2018;Jo and Yu, 2001;Leavey et al, 2017;Lee et al, 2015;Madl et al, 2015;Moreno et al, 2015;Tartakovsky et al, 2013;Xing et al, 2018;Yang et al, 2015;Zhu et al, 2007). In the context of legislative demands imposed by environmental authorities, the main focus of these studies has been on PM 10 and PM 2.5 mass, numbers of ultrafine particles (UFP), concentrations of gaseous pollutants such as NOx, CO and CO 2 and, more recently, volatile organic compounds (VOCs).…”