HK government admits holes in ozone understanding

Poor visibility across Hong Kong’s iconic harbour: the city has yet to fully achieve its current Air Quality Objectives

Hong Kong needs to intensify its efforts to fully understand the range of volatile organic compounds (VOCs) which cause smog and ozone, admits the government’s Environmental Protection Department (EPD), as leading environmental scientists call on the city to urgently enhance its database of key pollutants.

According to an EPD spokesman, “VOCs comprise a variety of chemical species which have different ozone formation potential. We see a need to collect more information on the key VOC species for better understanding of which species have higher contribution to ozone formation in the region, through air modelling and analysis.”

The spokesman told Blue Skies China the government is already actively working to improve the VOC database. “We will expand the VOC monitoring network in Hong Kong in the near future so as to capture more spatial variation information,” he says. In addition, the spokesman says a three-dimensional air quality monitoring system will be developed in Hong Kong to monitor ozone and PM2.5 formation and their transportation into and around Hong Kong. The HK$55 million system will use light detection and ranging (LiDAR) technology for tracking particulates, wind and ozone across a network of 15 LiDAR stations, and will be fully commissioned by May 2021.

The EPD’s comments come in response to criticism of the government’s emissions inventory from environmental campaigners: last month, two leading Hong Kong scientists wrote a submission to the Legislative Council’s Panel on Environmental Affairs claiming VOCs and other emissions are not adequately measured by the Hong Kong government. Professor Alexis Lau and Professor Xiang-qian Lao, of HKUST and Chinese University respectively, called on the government to urgently enhance Hong Kong’s emissions inventories with respect to VOCs which cause smog and ozone.

“Unfortunately, [Hong Kong’s] understanding of VOC is very limited, and hence it is difficult for the Air Quality Objectives (AQO) review working groups to identify and prioritize VOC control policies that can help reduce ozone. What we urgently need is to enhance our understanding of VOCs (in term of both the VOC emission inventory, and the ambient VOC concentrations) before we can decide which policy would be more effective for controlling the reactive VOCs and ozone,” they wrote.

According to the professors, the latest AQO review has identified a number of data and knowledge gaps, including, but not limited to:

  • sources and ambient concentrations of reactive VOCs
  • emission impacts for different traffic policies
  • updated health and economic data for impact analyses.

Lau and Lao urged the government to take stock of its knowledge gaps and make sure data connections and studies can be done the start of the next review, slated for 2024, while making gap-identification a formal and integral part of the AQO review process.