Characteristics of PM₂.₅, CO₂ and particle-number concentration in mass transit railway carriages in Hong Kong

Hailong ZHENG, Wenjing DENG, Yan CHENG, Wei GUO

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8 Citations (Scopus)

Abstract

Fine particulate matter (PM₂.₅) levels, carbon dioxide (CO₂) levels and particle-number concentrations (PNC) were monitored in train carriages on seven routes of the mass transit railway in Hong Kong between March and May 2014, using real-time monitoring instruments. The 8-h average PM₂.₅ levels in carriages on the seven routes ranged from 24.1 to 49.8 µg/m³, higher than levels in Finland and similar to those in New York, and in most cases exceeding the standard set by the World Health Organisation (25 µg/m³). The CO₂ concentration ranged from 714 to 1801 ppm on four of the routes, generally exceeding indoor air quality guidelines (1000 ppm over 8 h) and reaching levels as high as those in Beijing. PNC ranged from 1506 to 11,570 particles/cm3, lower than readings in Sydney and higher than readings in Taipei. Correlation analysis indicated that the number of passengers in a given carriage did not affect the PM₂.₅ concentration or PNC in the carriage. However, a significant positive correlation (p < 0.001, R² = 0.834) was observed between passenger numbers and CO₂ levels, with each passenger contributing approximately 7.7–9.8 ppm of CO₂. The real-time measurements of PM₂.₅ and PNC varied considerably, rising when carriage doors opened on arrival at a station and when passengers inside the carriage were more active. This suggests that air pollutants outside the train and passenger movements may contribute to PM₂.₅ levels and PNC. Assessment of the risk associated with PM₂.₅ exposure revealed that children are most severely affected by PM₂.₅ pollution, followed in order by juveniles, adults and the elderly. In addition, females were found to be more vulnerable to PM₂.₅ pollution than males (p < 0.001), and different subway lines were associated with different levels of risk. Copyright © 2016 Springer Science+Business Media Dordrecht.
Original languageEnglish
Pages (from-to)739-750
JournalEnvironmental Geochemistry and Health
Volume39
Issue number4
Early online dateJun 2016
DOIs
Publication statusPublished - Aug 2017

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Particulate Matter
Carbon Dioxide
railway
particulate matter
Carbon dioxide
carbon dioxide
Pollution
Subways
Time measurement
Air quality
train
Health
pollution
Air Pollutants
particle
Monitoring
World Health Organization
indoor air
Air
Industry

Citation

Zheng, H.-L., Deng, W.-J., Cheng, Y., & Guo, W. (2017). Characteristics of PM₂.₅, CO₂ and particle-number concentration in mass transit railway carriages in Hong Kong. Environmental Geochemistry and Health, 39(4), 739-750.

Keywords

  • CO₂
  • Hong Kong
  • Mass transit railway (MTR)
  • Particle-number concentration (PNC)
  • PM₂.₅