Long-term variation and evaluation of air quality across Hong Kong

Study of Air Quality Objectives (AQOs) and long-term changesofairpollutionplaysadeci-siveroleinformulatingandrefiningpollutioncontrolstrategies.Inthisstudy,10-yearvaria-tionsofsixmajorairpollutantswereanalyzedatsevenmonitoringsitesinHongKong.ThecontinuousdecreaseofannualaveragedconcentrationsofNO2,SO2,CO,PM2.5andPM10andnumbersofdayswithseverepollutionconditionsvalidatedtheefficiencyoftheseriesofairpollutioncontrolschemesimplementedbytheHongKonggovernment.However,thereisstillabiggaptomeettheultimatetargetsdescribedbytheWorldHealthOrganization.Be-sides,theconcentrationofO3atroadsideandurbanstationsincreasedby135%+/- 25%and37%+/- 18%from2011to2020,respectively,meanwhilethehighest8hraveragedO3con-centrationwasobservedas294 mu g/m3atbackgroundstationin2020,whichpointedouttheincreasingozonepollutioninHongKong.Therewasagreatdecreaseintheannualtimesofairqualityhealthindex(AQHI)layinginhigh,veryhigh andserious categoriesfrom2011to2020withthedecreaserateof89.70%,91.30%and89.74%atroadsidestations,and79.03%,95.98%and72.73%aturbanstations,respectively.Nevertheless,thenumberofdayscategorizedashigh oraboveatroadsidestationwastwicemorethanthatintheurbanstationduringthepasttenyears.Thus,morepoliciesandattentionsshouldbegiventotheroadsideairqualityanditsadversehealtheffecttopedestriansonstreet.(c) 2022TheResearchCenterforEco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V

Automated summary

The study examines the changes in six major air pollutants in Hong Kong over a ten-year period. It finds that the implemented pollution control schemes have been effective in reducing the concentrations of these pollutants, but there is still a gap to meet the targets set by the World Health Organization. The study also highlights an increasing trend in ozone pollution and the slower improvement in air quality health index at roadside stations, suggesting the need for more policies and attention to roadside air quality and its impact on pedestrians' health.