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(added on 2017/11/24)

Toxic air 毒氣熏天

Map created by CUHK SpatioEpi Group

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Ambient air pollution is emerging as one of the leading risk factors for ill health in the human population. The recent problem faced by people in India is particularly worrisome. In early November 2017, the Air Quality Index reached a historically high level, paralleling heavy smog in some cities. The Indian government had to close schools for 3 days in Delhi in their Capital region.

The map shows the distribution of particulate matter (PM) 2.5 over Indian subcontinent on 16 November 2017, and the disability-adjusted life-years (DALY, an index reflecting lost years of healthy life) of four selected diseases associated with air pollution in different states of India. As depicted by the coloured isolines of PM2.5 concentration, air pollution problem was more severe in the north-western part of India. As shown by graduated colours, the burden of three respiratory diseases, i.e. chronic obstructive pulmonary disease (COPD), tuberculosis and asthma, in north-western states of India was particularly higher. A higher burden of ischaemic heart disease was observed in south-western India, where PM 2.5 concentration level was moderate. Although both respiratory and cardiovascular diseases were associated with exposure to air pollutants, impact of air pollution on respiratory disease appears to be more direct.

The air pollutant data in the maps were obtained from the World Air Quality Index Website (, whereas corresponding epidemiological data were extracted from an article published in Lancet.


地圖顯示2017年11月16日印度次大陸的微細懸浮粒子的水平,並標示出印度各邦內四種與空氣污染相關的疾病的殘疾調整生命年(指數反映因病喪失的健康壽命)。顏色等值線標示出圖中地區的微細懸浮粒子的濃度,當中印度西北部的空氣污染問題明顯比較嚴重。依圖中顏色所示,印度西北各邦的三種呼吸系統疾病(慢性阻塞性肺病、肺結核及哮喘)的疾病負擔亦較高。缺血性心臟病則對印度西南部的人口影響較大,但該地區錄得中等濃度的微細懸浮粒子。雖然呼吸系統及心血管疾病同樣 地與空氣污染物相關,但空氣污染對呼吸道疾病的影響更為直接。