Spatial and Temporal Characteristics and Main Contributing Regions of High PM2.5 Pollution in Hong Kong

Abstract

Fine particulate matter (PM 2.5 ) pollution episodes occur frequently in most Chinese metropolises. Because Hong Kong is affected by the East Asian monsoon, its high PM 2.5 pollution is potentially contributed to by a combination of local and regional emissions. This study identified the spatial and temporal characteristics and contributing regions of PM 2.5 pollution episodes in Hong Kong. We analyzed the hourly monitoring data collected at various monitoring stations in Hong Kong for the year 2014 in addition to spatial distributions of PM 2.5 in China in the days preceding high pollution episodes, and we identified the spatial and temporal characteristics of high PM 2.5 pollution in Hong Kong. The relative contributions of local and regional sources to high PM 2.5 episodes were then quantified. Finally, backward trajectories of air masses arriving in Hong Kong during high PM 2.5 episodes were generated to determine the main contributing regions. The results indicated that PM 2.5 levels were higher in the northwestern and southeastern parts of Hong Kong and the Yuen Long station observed the most serious pollution, with a highest daily average PM 2.5 concentration of 118 µg m -3; other areas noted relatively lower concentrations, with maximum daily average concentrations less than 100 µg m -3. Regional sources accounted for almost 70% of the PM 2.5 pollution and were mostly from the northern and northeastern areas of Hong Kong. Six main contributing regions were identified: the northern region of Guangdong province, Henan-Shandong, the Yangtze River Delta, Jiangxi, Fujian, and Anhui-Hubei. Among these, Guangdong province contributed the highest proportion of the pollution. Because PM 2.5 is a major air pollutant in Hong Kong, the findings of this study will be useful for forecasting PM 2.5 pollution episodes. Moreover, the developed methodology can be extended to other pollutants if their characteristics and main contributing regions can be identified.

Differences in the Vertical Distribution of Aerosols, Nitrogen Dioxide, and Formaldehyde between Islands and Inland Areas: A Case Study in the Yangtze River Delta of China

“…DOAS has been widely used in studies of the vertical distribution characteristics of atmospheric components in different environments (suburban, regional, island, and offshore) in different regions, e.g., the Beijing-Tianjin-Hebei [9,[17][18][19], the Pearl River Delta region [13,20,21] and the YRD region [22][23][24][25][26][27]. This technology provides a promising method for the accurate monitoring and management of air pollution.…”

“…The most important advantage of the MAX-DOAS is that it can simultaneously monitor various atmospheric components, including aerosols, NO 2 , and HCHO, thereby overcoming the errors of atmospheric component monitoring using different instruments. MAX-DOAS has been widely used in studies of the vertical distribution characteristics of atmospheric components in different environments (suburban, regional, island, and offshore) in different regions, e.g., the Beijing-Tianjin-Hebei [9,[17][18][19], the Pearl River Delta region [13,20,21] and the YRD region [22][23][24][25][26][27]. This technology provides a promising method for the accurate monitoring and management of air pollution.…”