Abstract
Millions of pulmonary diseases, respiratory diseases, and premature deaths are caused by poor ambient air quality in developing countries, especially in China. A proven indicator of ambient air quality, atmospheric visibility (AV), has displayed continuous decline in China’s urban areas. A better understanding of the characteristics and the factors affecting AV can help the public and policy makers manage their life and work. In this study, long-term AV trends (from 1957–2016, excluding 1965–1972) and spatial characteristics of 31 provincial capital cities (PCCs) of China (excluding Taipei, Hong Kong, and Macau) were investigated. Seasonal and annual mean values of AV, percentage of ‘good’ (≥20 km) and ‘bad’ AV (<10 km), cumulative percentiles and the correlation between AV, socioeconomic factors, air pollutants and meteorological factors were analyzed in this study. Results showed that annual mean AV of the 31 PCCs in China were 14.30 km, with a declining rate of −1.07 km/decade. The AV of the 31 PCCs declined dramatically between 1973–1986, then plateaued between 1987–2006, and rebounded slightly after 2007. Correlation analysis showed that impact factors (e.g., urban size, industrial activities, residents’ activities, urban greening, air quality, and meteorological factors) contributed to the variation of AV. We also reveal that residents’ activities are the primary direct socioeconomic factors on AV. This study hopes to help the public fully understand the characteristics of AV and make recommendations about improving the air environment in China’s urban areas.
Highlights
Atmospheric visibility is defined as the maximum horizon distance between a person’s eye and the visible target against the background of the sky at certain weather conditions [1]
This indicated that atmospheric visibility (AV) in the provincial capital cities (PCCs) of China were relatively poor
We found that industrial SO2 emission and industrial dust emissions showed no significant correlation with the change of AV in the 31 PCCs that were observed, which is inconsistent with other study results
Summary
Atmospheric visibility is defined as the maximum horizon distance between a person’s eye and the visible target against the background of the sky at certain weather conditions [1]. Atmosphere 2018, 9, 318 temperature, etc.) and air pollutants (e.g., particulate matter, SO2 , NO2 , etc.). By eliminating specific weather conditions (e.g., fog, snow, and rain), the scattering and absorption of light by air pollutants occurs. AV is regarded as an applicable indicator for air quality [3,4,5,6,7,8,9,10,11,12]. Huang et al (2009) demonstrated the association between AV, air quality and death rates. They suggested that AV is significantly associated with elevated death rates and cardiovascular disease in Shanghai, China [13].
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