Trans-boundary air pollution in a city under various atmospheric conditions

Ming Luo; Xiangting Hou; Yefu Gu; Ngar-Cheung Lau; Steve Hung-Lam Yim

doi:10.1016/j.scitotenv.2017.11.001

Trans-boundary air pollution in a city under various atmospheric conditions

Sci Total Environ. 2018 Mar 15:618:132-141. doi: 10.1016/j.scitotenv.2017.11.001. Epub 2017 Nov 8.

Authors

Ming Luo¹, Xiangting Hou¹, Yefu Gu², Ngar-Cheung Lau³, Steve Hung-Lam Yim⁴

Affiliations

¹ Institute of Environment, Energy and Sustainability, The Chinese University of Hong Kong, Sha Tin, N.T., Hong Kong.
² Department of Geography and Resource Management, The Chinese University of Hong Kong, Sha Tin, N.T., Hong Kong.
³ Institute of Environment, Energy and Sustainability, The Chinese University of Hong Kong, Sha Tin, N.T., Hong Kong; Department of Geography and Resource Management, The Chinese University of Hong Kong, Sha Tin, N.T., Hong Kong.
⁴ Institute of Environment, Energy and Sustainability, The Chinese University of Hong Kong, Sha Tin, N.T., Hong Kong; Department of Geography and Resource Management, The Chinese University of Hong Kong, Sha Tin, N.T., Hong Kong; Centre for Environmental Policy and Resource Management, The Chinese University of Hong Kong, Sha Tin, N.T., Hong Kong. Electronic address: steveyim@cuhk.edu.hk.

PMID: 29127869
DOI: 10.1016/j.scitotenv.2017.11.001

Abstract

Trans-boundary air pollution (TAP) is a crucial factor affecting air quality, and its contribution may vary over time and differ under various atmospheric conditions. This study firstly applies an integrated statistical scheme to estimate the contributions of TAP and local sources to air pollutants in a city, and then investigate the influences of tropical cyclones (TC) on TAP. Hong Kong is chosen as an example because of its significant and special TAP characteristics. This study focuses on four major air pollutants, namely, respirable and fine suspended particulates (RSP/PM₁₀ and FSP/PM_2.5), sulfur dioxide (SO₂), and nitrogen dioxide (NO₂), from 2002 to 2013. Our results show that, on average, TAP is the major contributor of the annual RSP, FSP, SO₂, and NO₂ in Hong Kong. We estimate that when a TC is approaching, the increase in pollutant concentration in Hong Kong is mainly due to the increase in TAP contribution by the strengthened northerly wind at higher level of atmosphere (≥900hPa). These changes are accompanied by decreases in precipitation and increases in northerly/north-easterly wind, which may prolong the lifetime of pollutants, enhancing pollutant transport from mainland China to Hong Kong.

Keywords: Air pollution; Non-negative matrix factorization; Trans-boundary contribution; Tropical cyclones.