Data source: WHO & International Energy Agency
Map created by CUHK SpatioEpi Group
Apart from ozone, nitrogen dioxide and sulphur dioxide, particulate matter (PM) is another common urban air pollutant. The map shows the mean annual exposure to PM10 in urban population and the proportion of fossil fuel used in national energy consumption.
As depicted by graduated colours, the concentration of PM10 in outdoor air was higher in Asian urban areas. Of these, some were from countries with high dependence on fossil fuel, as indicated by coloured symbols. According to World Health Organization guidelines, the air quality standard for annual average of PM10 is below 20 micrograms per cubic metre. Cities achieving this standard were however limited to those in North America, Oceania and a few countries in Europe. In addition to developing cleaner fuels, energy saving through lifestyle change and enforcing air quality regulations are two feasible ways to change the current situation.
The data for the map were obtained from World Health Organization and International Energy Agency.
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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