Re ECF Project: 2009-07

Project Title: Study of photochemical air pollution in Hong Kong

Applicant: Prof. Tao WANG of The Hong Kong Polytechnic University

Total Approved Grant: $6,554,936

Duration: 2/7/2010 to 30/6/2014

Project Status/Remarks: Completed

The objectives of the proposed program are:

  • to obtain a comprehensive picture of oxidants pollution in Hong Kong;
  • to quantify the roles of synoptic and mesoscale meteorology in the trapping of air pollutants within Hong Kong, and in the transport of air pollutants to Hong Kong from other cities in the PRD (regional transport) and from other parts of Asia (super-regional transport);
  • to understand the sources and key chemical pathways involved in the formation of oxidants in a sub-tropical climate; and
  • to develop integrated tools and the human resources needed for the further study of air pollution and climate in PRD and other rapidly developing regions of China.

Summary of the Findings/Outcomes:
  • The ambient concentrations of NOx and CO have been decreasing at most of stations in Hong Kong. Meanwhile, the O3 concentrations have still shown an increasing trend in most areas in HK-PRD region. The local ozone production in Hong Kong has been reduced through the strict VOC control by the government. However, the background ozone levels have increased more significantly, which were mainly attributed to the regional transport from the PRD and eastern China. This regional impact has negated the local control efforts of Hong Kong.
  • HONO was found to be a dominant radical (OH) source at Tung Chung (TC), not only in the morning but also throughout the daytime. Some new insights about direct emission and heterogeneous production of HONO on aerosol and ground surfaces were obtained. ‘Missing' daytime source of HONO was found at TC, and further analysis revealed the possible contribution by aerosol surface. The emission factors of HONO were derived from the field measurement. Our results also suggested the important role of sea surface in the heterogeneous HONO formation and hence atmospheric photochemistry in the coastal areas like Hong Kong.