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Toxic air 毒氣熏天

(added on 2017/11/24)

©2017 SpatioEpi.com
Map created by CUHK SpatioEpi Group


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 (http://aqicn.org/city/delhi/dtu/), 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。


Related Article

Particulate matter (PM) 懸浮粒子

Particulate matter represents a complex mixture of small particles and liquid droplets suspended in the air. Major sources of particulate matter include construction activities, road dust re-suspension and combustion.

Particulate matter with aerodynamic diameter smaller than 10 micrometres (μm) (PM10) is already small enough to pass through nose and respiratory tract and enter our lungs. Chronic exposure to particulate matter increases the risk of cardiovascular and respiratory diseases, or even lung cancer. Those particulate matter smaller than 2.5 μm (PM2.5), also known as fine suspended particles, is especially harmful. It is one of the most important parameters for air pollution monitoring.

In Hong Kong, Air Quality Health Index (AQHI) was introduced to replace the late Air Pollution Index in December 2013 from Environmental Protection Department, HKSAR. Individuals with lung and heart disease, influenza, asthma, elderly people and children are sensitive to PM. They are advised to reduce physical exertion and outdoor activities and avoid prolonged stay in areas with heavy traffic when AQHI is at high health risk category or higher.


氣動力學直徑小於十微米的顆粒物可以經鼻腔及呼吸道進入肺部,長期暴露於此類可吸入顆粒物會增加患上心血管病、呼吸系統疾病甚至肺癌等風險。 其中小於2.5微米的懸浮粒子,亦稱微細懸浮粒子,尤其有害。它是衡量空氣污染指標的其一重要成份。

香港政府環境保護署於2013年12月以空氣質素健康指數代替舊有的空氣污染指數。心肺疾病、感冒或哮喘患者與及長者和小童都可能對可吸入顆粒物特別敏感,當空氣質素健康指數健康風險級別為高或以上水平時 ,他們都應減少體力消秏及戶外活動,亦應避免長時間在交通繁忙的街道上逗留以減少顆粒物的吸入數量。

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