In-car particulate matter exposure across ten global cities

• Published in: The Science of the total environment Vol. 750; p. 141395
• Main Authors: Kumar, Prashant, Hama, Sarkawt, Nogueira, Thiago, Abbass, Rana Alaa, Brand, Veronika S., Andrade, Maria de Fatima, Asfaw, Araya, Aziz, Kosar Hama, Cao, Shi-Jie, El-Gendy, Ahmed, Islam, Shariful, Jeba, Farah, Khare, Mukesh, Mamuya, Simon Henry, Martinez, Jenny, Meng, Ming-Rui, Morawska, Lidia, Muula, Adamson S., Shiva Nagendra, S.M., Ngowi, Aiwerasia Vera, Omer, Khalid, Olaya, Yris, Osano, Philip, Salam, Abdus
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.01.2021
• Subjects: CArE-Cities Project; Commuters exposure; Developing countries; Exposure mitigation; Particulate matter; Transport mode; Developing countries; Transport mode; Commuters exposure; CArE-Cities Project; Particulate matter; Exposure mitigation
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2020.141395

Cars are a commuting lifeline worldwide, despite contributing significantly to air pollution. This is the first global assessment on air pollution exposure in cars across ten cities: Dhaka (Bangladesh); Chennai (India); Guangzhou (China); Medellín (Colombia); São Paulo (Brazil); Cairo (Egypt); Sulaymaniyah (Iraq); Addis Ababa (Ethiopia); Blantyre (Malawi); and Dar-es-Salaam (Tanzania). Portable laser particle counters were used to develop a proxy of car-user exposure profiles and analyse the factors affecting particulate matter ≤2.5 μm (PM2.5; fine fraction) and ≤10 μm (PM2.5–10; coarse fraction). Measurements were carried out during morning, off- and evening-peak hours under windows-open and windows-closed (fan-on and recirculation) conditions on predefined routes. For all cities, PM2.5 and PM10 concentrations were highest during windows-open, followed by fan-on and recirculation. Compared with recirculation, PM2.5 and PM10 were higher by up to 589% (Blantyre) and 1020% (São Paulo), during windows-open and higher by up to 385% (São Paulo) and 390% (São Paulo) during fan-on, respectively. Coarse particles dominated the PM fraction during windows-open while fine particles dominated during fan-on and recirculation, indicating filter effectiveness in removing coarse particles and a need for filters that limit the ingress of fine particles. Spatial variation analysis during windows-open showed that pollution hotspots make up to a third of the total route-length. PM2.5 exposure for windows-open during off-peak hours was 91% and 40% less than morning and evening peak hours, respectively. Across cities, determinants of relatively high personal exposure doses included lower car speeds, temporally longer journeys, and higher in-car concentrations. It was also concluded that car-users in the least affluent cities experienced disproportionately higher in-car PM2.5 exposures. Cities were classified into three groups according to low, intermediate and high levels of PM exposure to car commuters, allowing to draw similarities and highlight best practices. [Display omitted] •Particulate matter (PM) exposure in cars was measured across ten global cities.•Windows-open scenarios resulted in the highest PM10 and PM2.5 concentrations.•PM exposure was significantly higher during morning-peak hours in most cities.•Recirculation showed up to 80% less in-car PM2.5 compared to windows-open.•Off-peak trips showed up to 73% less PM2.5 exposure compared to morning-peak hours.