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| Characterization and relationship of long-term visibility and air pollutant changes in the Hongkong region. |
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Abstract 40 years (1968~2007) visibility and 24 years (1984~2007) air quality monitoring data from Hongkong were analyzed to examine the relationship between atmospheric environmental degradation in terms of reduced visibility (RV) and air pollutant concentration change by multiple regression analysis method. The time with RV in Hongkong increased 3.1% during 1968~2007. The increase trend was mild during 1968~1989 (0.7% per decade), but being sharp from the 1990s (1990~2007, 7.3% per decade), simultaneously with increase in surface ozone concentration. Time with RV correlated well with NO2 and NOx before 1993, but with O3, SO2 and NO2 after 1993. The visibility degradation in Hongkong related to photochemical smog before 1993, but afterwards, it was also affected by aerosol smog associated with sulfate besides photochemical smog.
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Received: 20 October 2008
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