From: Andy Soos, ENN
Published September 28, 2011 02:47 PM

Most Polluted Cities in the World

In many cities air pollution is reaching levels that threaten people's health according to an unprecedented compilation of air quality data released today by WHO (World Health Organization). The information includes data from nearly 1100 cities across 91 countries, including capital cities and cities with more than 100,000 residents. WHO estimates more than 2 million people die every year from breathing in tiny particles present in indoor and outdoor air pollution. PM10 particles, which are particles of 10 micrometers or less, which can penetrate into the lungs and may enter the bloodstream, can cause heart disease, lung cancer, asthma, and acute lower respiratory infections. The WHO air quality guidelines for PM10 is 20 micrograms per cubic meter (µg/m3) as an annual average, but the data released today shows that average PM10 in some cities has reached up to 300 µg/m3.

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India, Pakistan and Mongolia were also amongst the worst for pollution in cities whilst Canadian and American cities had some of the best scores. For example, Washington has a score of just 18 micrograms per cubic meter of airborne particles smaller than 10 micrometers.

The WHO report found that the Iranian city of Ahvaz had the highest measured level of airborne particles smaller than 10 micrometres. The recommended upper limit for these particles set by the WHO is 20 micrograms per cubic metre- in Ahvas the annual average was a substantial 372 micrograms per cubic metre which is 19 times over the limit. Another Iranian city, Sanandaj had 254 micrograms per cubic meter.

In both developed and developing countries, the largest contributors to urban outdoor air pollution include motor transport, small-scale manufacturers and other industries, burning of biomass and coal for cooking and heating, as well as coal-fired power plants. Residential wood and coal burning for space heating is an important contributor to air pollution, especially in rural areas during colder months.

“Local actions, national policies and international agreements are all needed to curb pollution and reduce its widespread health effects" said Dr Michal Krzyzanowski, Head of the WHO European Center for Environment and Health in Bonn, Germany. "Data from air quality monitoring that is released today, identify regions where action is most needed and allows us to assess the effectiveness of implemented policies and actions.”

The world's average PM10 levels by region range from 21 to 142 ug/m3, with a world's average of 71 ug/m3.   The eastern Mediterranean have some of the worst area followed by Africa and the Western Pacific.

For further information:  http://www.who.int/mediacentre/news/releases/2011/air_pollution_20110926/en/index.html or http://www.who.int/phe/health_topics/outdoorair/databases/en/index.html

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