1. Air quality on UK diesel and hybrid trains.
- Author
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Font, Anna, Hedges, Michael, Han, Yiqun, Lim, Shanon, Bos, Brendan, Tremper, Anja H., and Green, David C.
- Subjects
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AIR quality , *DIESEL particulate filters , *DIESEL motors , *PARTICULATE matter , *AIR travel , *NITROGEN dioxide , *CARBON-black - Abstract
[Display omitted] • In-train air quality in UK diesel trains tested for 13 different train classes. • Means were PM 10 : 8–52; PM 2.5 : 4–36; BC: 1–11; NO 2 : 28–201 (µg/m3); UFP: 225–9131 #/cm3. • Large in-train variability was observed and associated with multiple factors. • Trains under 10 years old had the lowest in-train PM concentrations. • UK diesel trains measured lower PM 2.5 and PNC than other transport modes. Concentrations of particulate matter (PM 10 , PM 2.5), ultrafine (UFP), particle number (PNC), black carbon (BC), nitrogen dioxide (NO 2) and nitrogen oxides (NO X) were measured in train carriages on diesel and bi-mode trains on inter-city and long-distance journeys in the United Kingdom (UK) using a high-quality mobile measurement system. Air quality on 15 different routes was measured using highly-time resolved data on a total of 119 journeys during three campaigns in winter 2020 and summer 2021; this included 13 different train classes. Each journey was sampled 4–10 times with approximatively 11,000 min of in-train concentrations in total. Mean-journey concentrations were 7.552 µg m−3 (PM 10); 3.936 µg m−3 (PM 2.5); 333–11,300 # cm−3 (PNC); 225–9,131 # cm−3 (UFP); 0.6–11 µg m−3 (BC); 28–201 µg m−3 (NO 2); and 130–3,456 µg m−3 (NO X). The impact of different factors on in-train concentrations was evaluated. The presence of tunnels was the factor with the largest impact on the in-train particle concentrations with enhancements by a factor of 40 greater than baseline for BC, and a factor 6 to 7 for PM and PNC. The engine fuel mode was the factor with the largest impact on NO 2 with enhancements of up to 14-times larger when the train run on diesel compared to the times running on electric on hybrid trains. Train classes with an age < 10 years observed the lowest in-train PM, BC and NO X concentrations reflecting improvements in aspects of rail technology in recent years. Air quality on UK diesel trains is higher than ambient concentrations but has lower PM 2.5 and PNC than most other transport modes, including subway systems, diesel and petrol cars. This paper adds significantly to the evidence on exposure to poor air quality in transport micro-environments and provides the industry and regulatory bodies with reference-grade measurements on which to establish in-train air quality guidelines. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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