Author: Antonio Da Roza

Date: 5/8/10

A time-based analysis shows that Hong Kong is affected by local pollution 53% of the days of a year, whilst mainland sources are the primary influence only 36% of the time. [1]

The time-based apportionment method shows that the average concentrations for most pollutants in Hong Kong are higher during winter than summer.

The Pearl River Delta affects Hong Kong’s air pollution in winter, and local sources play the biggest role through summer.

Overall, regional sources are the primary influence on Hong Kong’s air 132 days a year; while local sources are the crucial factor nearly 53% of the time (on 192 days), meaning that Hong Kong can indeed control the source of its air pollution problem more often that not.

Health impacts are a function of the concentrations at which pollutants are inhaled, as well as the duration of exposure, making a time-based analysis the most sensitive way to measure the health impact air pollution has.

See Also

  1. Cross-border pollution
  2. Total emissions calculation
  3. Source-based calculation
  4. Seasonal influences on air pollution


  1. ‘Relative Significance of Local Vs Regional Sources’, Civic Exchange and Hong Kong University of Science and Technology, March 2007 - last accessed 7/8/10