Via WHO, a news release: Air quality deteriorating in many of the world’s cities. Excerpt:
The latest available data have prompted WHO to call for greater awareness of health risks caused by air pollution, implementation of effective air pollution mitigation policies; and close monitoring of the situation in cities worldwide.
“Too many urban centres today are so enveloped in dirty air that their skylines are invisible,” said Dr Flavia Bustreo, WHO Assistant Director-General for Family, Children and Women's Health. “Not surprisingly, this air is dangerous to breathe. So a growing number of cities and communities worldwide are striving to better meet the needs of their residents - in particular children and the elderly."
In April 2014, WHO issued new information estimating that outdoor air pollution was responsible for the deaths of some 3.7 million people under the age of 60 in 2012. The Organization also emphasised that indoor and outdoor air pollution combined are among the largest risks to health worldwide.
There are many components of air pollution, both gaseous and solid. But high concentrations of small and fine particulate pollution is particularly associated with high numbers of deaths from heart disease and stroke, as well as respiratory illnesses and cancers. Measurement of fine particulate matter of 2.5 micrometers or less in diameter (PM2.5) is considered to be the best indicator of the level of health risks from air pollution.
In high-income countries, 816 cities reported on PM2.5 levels with another 544 cities reporting on PM10, from which estimates of PM2.5 can be derived. In low- and middle-income countries, however, annual mean PM2.5 measurements could be accessed in only 70 cities; another 512 cities reported on PM10 measurements.