15-Year PM2.5 Trends in the Pearl River Delta Region and Hong Kong from Satellite Observation

Changqing Lin; Ying Li; Alexis K.H. Lau; Chengcai Li; Jimmy C.H. Fung

doi:10.4209/aaqr.2017.11.0437

15-Year PM2.5 Trends in the Pearl River Delta Region and Hong Kong from Satellite Observation

Changqing Lin¹^,2, Ying Li³, Alexis K.H. Lau ¹^,2^,4, Chengcai Li⁵, Jimmy C.H. Fung²^,4^,6

¹Department of Civil and Environmental Engineering, the Hong Kong University of Science and Technology, Hong Kong, China
²Institute for the Environment, the Hong Kong University of Science and Technology, Hong Kong, China
³Department of Ocean Science and Engineering, Southern University of Science and Technology, Shenzhen, China
⁴Division of Environment and Sustainability, the Hong Kong University of Science and Technology, Hong Kong, China
⁵Department of Atmospheric and Oceanic Sciences, School of Physics, Peking University, Beijing, China
⁶Department of Mathematics, the Hong Kong University of Science and Technology, Hong Kong, China

Received: November 1, 2017
Revised: February 10, 2018
Accepted: April 9, 2018
Download Citation: ||https://doi.org/10.4209/aaqr.2017.11.0437

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Cite this article:
Lin, C., Li, Y., Lau, A.K., Li, C. and Fung, J.C. (2018). 15-Year PM2.5 Trends in the Pearl River Delta Region and Hong Kong from Satellite Observation. Aerosol Air Qual. Res. 18: 2355-2362. https://doi.org/10.4209/aaqr.2017.11.0437

HIGHLIGHTS

PM_2.5 trends in the PRD region and HK were in line with those of emissions.
PM_2.5 increased more in the central PRD region from 2001 to 2005.
PM_2.5 reduced greatly in the non-central PRD region from 2011 to 2015.
PM_2.5 changes in HK were greatly affected by the regional transport.
PM_2.5 declines in central HK suggested the beneficial effect of local efforts.

ABSTRACT

Rapid economic development and urbanization have caused severe pollution from PM_2.5 in the Pearl River Delta (PRD) region of China. Characterizing the long-term PM_2.5 trends is a basic requirement for evaluating the effectiveness of the implemented control measures and for guiding future policies. Traditional characterization has relied on fixed-site measurements, leading to incomplete spatial and temporal coverage. In this study, we took advantage of satellite-derived PM_2.5 data at a resolution of 0.01° × 0.01° and assessed the long-term PM_2.5 trends on a city scale in the PRD region and on a district scale in Hong Kong from 2001 to 2015. The results of our analysis showed that the PM_2.5 concentration in the PRD region and Hong Kong worsened during the 10^th Five-Year-Plan (FYP) period (2001–2005) and started to improve during the 11^th FYP period (2006–2010). The improvement accelerated during the 12^th FYP period (2011–2015). These trends were in line with the trends of air-pollutant emissions. In addition, the cities in the central area of the PRD region experienced higher PM_2.5 concentration increase during the 10^th FYP period and a greater reduction in the concentration afterward during the 11^th FYP period than those in the non-central area of the PRD region. During the 12^th FYP period, PM_2.5 concentrations substantially lessened for most of the cities in the PRD region, particularly for those in the non-central area of the PRD region. For Hong Kong, the rates of increase and decrease in the PM_2.5 concentration generally exhibited gradients from the northwest to the southeast, suggesting effects from the regional transport of air pollutants. A group of districts in the central urban area of Hong Kong also experienced a substantial decline in the PM_2.5 concentration during the 11^th and 12^th FYP periods, suggesting the beneficial effects of local control efforts.