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Most Cities Fail WHO Guidelines on Air Quality

Most cities in the world fail to meet WHO guidelines for safe air quality levels, putting people - particularly young children and the elderly - at additional risk of respiratory disease and other health problems.

That's the key result of a World Health Organisation (WHO) survey of 1600 cities that monitor outdoor (ambient) air pollution in 91 countries the.

The survey does not, however, reveal the least and most polluted cities in the world because many cities, including some expected to be among the most polluted, do not collect information or report on outdoor air quality. WHO therefore cannot compare cities based on their levels of outdoor air pollution.

Rather, WHO has brought together the available information on ambient air pollution in order to raise awareness and facilitate adequate responses to protect public health from the adverse impacts of outdoor air pollution.

The overriding message though is that it does appear that living in cities is bad for your health. and, whereas cities in Europe and North America do fare better, many of them still have room for improvement.

City breakdown

 map of the world showing cities with air pollution

Of the cities for which data is available (right: click on the image for a larger version), some of the highest rates of air pollution are in the poorest regions, especially where cooking is done on open fires and climate contributes to the problem:

  • Kabul and other cities in Afghanistan;
  • Ahvaz in Iran;
  • Karachi and other cities in Pakistan;
  • Delhi, Gwalior and several cities in India;
  • most cities in Bangladesh;
  • various Mongolian cities such as Ulaanbaatar;
  • Dakar in Senegal;
  • Beau Bassin/Rose Hill, Coromandel in Mauritius;
  • Kathmandu in Nepal;
  • and cities in Bahrain, Oman, Qatar, Saudi Arabia and United Arab Emirates.

Several Turkish cities also score highly but not as high as these, and about the same as Chinese cities such as Lanzhou and Beijing.

Compared to the last study in 2011, more cities are monitoring outdoor air quality, reflecting growing recognition of air pollution's health risks.

Only 12% of the people living in these monitored cities breathe air that complies with WHO air quality guideline levels. About half of the urban population is exposed to air pollution at least 2.5 times higher than the recommended levels.

What's more, as car ownership and the use of coal burning power stations increase,  air quality is getting worse in most cities where there is sufficient data to enable comparison with previous years.

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.

Sporadic data

Data is sporadic: in high-income countries, 816 cities reported on the smaller PM2.5 particulate 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 were available 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 that 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.

"We cannot buy clean air in a bottle, but cities can adopt measures that will clean the air and save the lives of their people," said Dr Carlos Dora, Coordinator, Interventions for Healthy Environments, WHO Department of Public Health, Environmental and Social Determinants of Health.

Improving air quality

Recommended measures include:

  • ensuring that houses are energy efficient;
  • compact urban development;
  • good access to public transport routes;
  • appealing and safe street design for pedestrians and cyclists;
  • good management of waste;
  • plenty of trees to clean the air;
  • the use of pollution-free energy supplies.

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.

Souces of ambient air pollution

Industries, households, cars and trucks emit complex mixtures of air pollutants, many of which are harmful to health. Of all of these pollutants, fine particulate matter has the greatest effect on human health.

Most fine particulate matter comes from fuel combustion, both from mobile sources such as vehicles and from stationary sources such as power plants, industry, households or biomass burning.

Health effects

Lung cancer, chronic obstructive pulmonary disease (COPD) and cardiovascular diseases are all associated with breathing particulates in the air. Worldwide, this is estimated to cause about 16% of lung cancer deaths, 11% of COPD deaths, and more than 20% of ischaemic heart disease and stroke.

Low- and middle-income countries suffer disproportionately from this burden.

Despite the improvement in the number of cities conducting air quality monitoring, many cities in low and middle income countries still lack the capacity to do so. There is a particular shortage of data in WHO's Africa and Eastern Mediterranean regions.

The organisation hopes that by the time the next survey is conducted many more cities will be publishing this type of data in the interests not only of their citizens' health but of their economies.