Fine-scale spatial structure of air pollutant concentrations along bus routes

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review

16 Scopus Citations
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Original languageEnglish
Pages (from-to)1-7
Journal / PublicationScience of the Total Environment
Online published3 Dec 2018
Publication statusPublished - 25 Mar 2019


Air pollution measurements were made at 5 s intervals along a bus route in Hong Kong, chosen to avoid frequent intersections or traffic jams. This allowed periodic pollutant concentration patterns in bus-derived pollutants to be explored using Fourier analysis. The analysis showed the defining role of the bus stops in terms of NOX and PM2.5 concentrations, which have profiles with a sawtooth form. Early in inter-stop segments, concentrations are high, followed by a decline. This arises from high emissions during the acceleration away from the bus stop, then lower emissions during cruise and de-acceleration. This pattern can be enhanced on sections of the route where buses are frequent as pollutants accumulate from the larger number of buses. The high concentrations just beyond bus stops may have implications for planning bus routes and the positioning of bus stops.

Research Area(s)

  • Bus stops, Diesel pollutants, Fourier analysis, On-road measurements, Roadside pollution, Vehicle emission model