Impacts of atmospheric environment on mortality of respiratory and cardiovascular diseases in Chinese megacities: a retrospective study based on long time series visibility observations

Epidemiological studies showed that PM2.5 was one main air pollutant that associated with adverse health effects. However, nationwide observation of PM2.5 began after 2013, which resulted a lack of assessment of air pollution on human health before that time. Visibility is an important indicator strongly correlated with meteorological factors and air pollutants and it could be regarded as an effective alternative index for atmospheric environment. Studies have shown significant associations between visibility and health outcomes. Using long-term visibility data, we applied a semi-parametric generalized additive model to explore the association between different visibility grades and mortality risk in 8 cities from 2005 to 2016. Our results indicated that decrease of visibility levels in Beijing, Shanghai, Guangzhou, Chengdu, Urumqi, and Shenyang would significantly increase mortality risk among sensitive populations on different lag days. These findings were consistent with the analytical results from the PM2.5 model. The association between visibility and mortality risk can serve as an indicator of air quality in areas and periods where fine particulate matter observations were lacked, effectively filling the gap in health effect assessment, and providing basic information for decision-making.