Project Background

On many days of the year, the poor air quality of the Hong Kong and Pearl River Delta region is easily observed by the naked eye. Commonly known as “smog” or “photochemical smog”, the air quality of the region affects the health of the residents and visitors, the natural environment, and can have direct impacts on industries such as air travel and tourism.

Two important pollutants that create photochemical smog are ozone (O3) and PM2.5 (particles with diameters smaller than 2.5 micrometers). While ozone is needed in the upper level atmosphere to provide protection against UV rays, at the ground level it is known to have negative impacts on human and environmental health. PM2.5 is a lesser-known pollutant that is currently gaining interest worldwide, proving to have significant impacts on human health, visibility, and regional climate.

A view looking towards Hong Kong's mountains from Shenzhen, China. The top view was after several days of heavy rain, the bottom one taken on a very hazy day. The buildings in the picture are approximately 1 km away.

A challenge in understainding the air pollutant concentrations in the Pearl River Delta is not only the emissions of air pollutant and related precursors in the region, but also the complexity of the terrain and weather patterns. The meteorology of the region is complex, affected by the mountainous landscape, the river delta, and the surrounding ocean.

A view from Victoria Peak, Hong Kong - showing the moutainous region, surrounded by the ocean. Below the clouds, a brownish haze can be seen over the city.