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.
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.
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