WHO data: global annual PM10 increased by 6% during recent 3-year period; based on data from 851 cities
8 May 2014
Air quality in most cities worldwide that monitor outdoor (ambient) air pollution fails to meet World Health Organization (WHO) guidelines for safe levels, putting people at additional risk of respiratory disease and other health problems, according to WHO’s expanded ambient (outdoor) air pollution (AAP) in cities database 2014.
WHO’s 2014 AAP database consists mainly of urban air quality data—annual means for PM10 and/or PM2.5—and covers 1,600 cities across 91 countries. Only 12% of the people living in cities reporting on air quality reside in cities where this complies with WHO air quality guideline levels. About half of the urban population being monitored is exposed to air pollution that is at least 2.5 times higher than the levels WHO recommends—putting those people at additional risk of serious, long-term health problems, the UN organization said.
The 2014 database covers the period from 2008 to 2013, with the majority of values for the years 2011 and 2012. A total of 851 cities in 72 countries are present in both the 2011 and 2014 versions of the database, with air quality data for different years. The 2011 version of the database contains data for 2010 or earlier, and the 2014 version for 2012 or earlier.
Globally, annual PM10 levels are estimated to increase by 6% during the recent three‐year periods (2009 to 2012 or earlier period) as assessed in cities present in both databases and weighted by regional urban population.
WHO notes that the results for the 851 cities are to be interpreted with caution, as yearly variations due, for example, to climatic changes can be important and 3‐year comparisons do not necessarily represent trends, in particular when changes are limited.
Primary source of data has been compiled from official national/sub-national reports, national/ sub-national web sites containing measurements of PM10 or PM2.5, and relevant national agencies.
Measurements reported by the following regional networks were used: the Asian Clean Air Initiative for Asia, and Airbase for Europe. In the absence of data from the previous sources, data from: (a) UN agencies; (b) Development agencies; and (c) articles from peer-reviewed journals were used.
Annual mean concentrations of particulate matter (PM10 and/or PM2.5) based on daily measurements, or data which could be aggregated into annual means, were included in the database. In the absence of annual means, measurements covering a more limited period of the year were exceptionally used.
In most cities where there is enough data to compare the situation today with previous years, air pollution is getting worse, WHO said. Many factors contribute to this increase, including reliance on fossil fuels such as coal-fired power plants, dependence on private transport motor vehicles, inefficient use of energy in buildings, and the use of biomass for cooking and heating.
But some cities are making notable improvements, demonstrating that air quality can be improved by implementing policy measures such as banning the use of coal for “space heating” in buildings, using renewable or “clean” fuels for electricity production, and improving efficiency of motor vehicle engines.
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 centers today are so enveloped in dirty air that their skylines are invisible. 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.—Dr. Flavia Bustreo, WHO Assistant Director-General for Family, Children and Women’s Health
Earlier this year, 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 emphasized that indoor and outdoor air pollution combined are among the largest risks to health worldwide. (Earlier post.)
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.
The report notes that individual cities can take local action to improve air quality and thus go against regional trends. And good air quality can go hand in hand with economic development, as indicated by some major cities in Latin America which meet, or approach, the WHO air quality guidelines.
Measures include ensuring that houses are energy efficient, that urban development is compact and well served by public transport routes, that street design is appealing and safe for pedestrians and cyclists, and waste is well managed. Such activities not only clean the air but can also serve as a catalyst for local economic development and the promotion of healthy urban lifestyles.
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