WHO releases country estimates on air pollution exposure and health impact (27 September 2016)

The World Health Organization (WHO) has released global and country estimates on air pollution exposure.

Background information:

Air pollution is a major environmental risk to health.

It is categorized as Ambient (outdoor) air pollution and Indoor (household) air pollution.

WHO estimates that in 2012, some

  • 72% of outdoor air pollution-related premature deaths were due to ischaemic heart disease and strokes, while
  • 14% of deaths were due to chronic obstructive pulmonary disease or acute lower respiratory infections, and
  • 14% of deaths were due to lung cancer.

By reducing air pollution levels, countries can reduce the burden of disease from stroke, heart disease, lung cancer, and both chronic and acute respiratory diseases, including asthma.

The lower the levels of air pollution, the better the cardiovascular and respiratory health of the population will be, both long- and short-term.

The “WHO Air quality guidelines” provide an assessment of health effects of air pollution and thresholds for health-harmful pollution levels.

Particulate Matter

Particulate matter consists of a complex mixture of solid and liquid particles of organic and inorganic substances suspended in the air.

The major components of PM are sulphates, nitrates, ammonia, sodium chloride, black carbon, mineral dust and water. The most health-damaging particles are those with a diameter of 10 μm or less, which can penetrate and lodge deep inside the lungs. Both short- and long-term exposure to air pollutants have been associated with health impacts.

PM2.5: Particulate Matter with a diameter less than 2.5 microns

PM10: Particulate Matter with a diameter less than 10 microns

While a number of air pollutants are associated with significant excess mortality or morbidity, including NOx, ozone, carbon monoxide and sulfur dioxides in particular, PM2.5 is the air pollutant that has been most closely studied and is most commonly used as proxy indicator of exposure to air pollution more generally.

Guideline values

10 μg/m3 annual mean
25 μg/m3 24-hour mean

PM2.5 includes pollutants such as sulfate, nitrates and black carbon, which penetrate deep into the lungs and in the cardiovascular system, posing the greatest risks to human health.

20 μg/m3 annual mean
50 μg/m3 24-hour mean

Air pollution and Sustainable Development Goals

Air pollution is used as a marker of sustainable development, as sources of air pollution also produce climate-modifying pollutants (e.g. CO2 or black carbon).

Policies to address air pollution also generate a range of benefits to human health, not only through air quality improvements but also other health benefits, such as injury prevention or enabling physical activity.

SDG Indicator 3.9.1: Mortality rate attributed to household and ambient air pollution for the health goal (SDG 3).

SDG Indicator 11.6.2: Annual mean levels of fine particulate matter (PM2.5) in cities (population-weighted) for the urban sustainable development goal (SDG 11).

SDG Indicator 7.1.2: Proportion of population with primary reliance on clean fuels and technologies for the sustainable energy goal (SDG 3).

Key Messages:

In 2014, 92% of the world population was living in places where the WHO air quality guidelines levels were not met.

The modelled estimates indicate that in 2014 only about one in ten people breathed clean air, as defined by the WHO Air quality guidelines.

A 2013 assessment by WHO’s International Agency for Research on Cancer (IARC) concluded that outdoor air pollution is carcinogenic to humans, with the particulate matter component of air pollution most closely associated with increased cancer incidence, especially cancer of the lung. An association also has been observed between outdoor air pollution and increase in cancer of the urinary tract/bladder.

Ambient (outdoor air pollution) in both cities and rural areas was estimated to cause 3 million premature deaths worldwide in 2012. This mortality is due to exposure to small particulate matter of 10 microns or less in diameter (PM10), which cause cardiovascular and respiratory disease, and cancers.

Some 88% of those premature deaths occurred in low- and middle-income countries, and the greatest number in the WHO Western Pacific and South-East Asia regions.

Policies and investments supporting cleaner transport, energy-efficient housing, power generation, industry and better municipal waste management would reduce key sources of urban outdoor air pollution.

Reducing outdoor emissions from household coal and biomass energy systems, agricultural waste incineration, forest fires and certain agro-forestry activities (e.g. charcoal production) would reduce key rural and peri-urban air pollution sources in developing regions.

Reducing outdoor air pollution also reduces emissions of CO2 and short-lived climate pollutants such as black carbon particles and methane, thus contributing to the near- and long-term mitigation of climate change.

In addition to outdoor air pollution, indoor smoke is a serious health risk for some 3 billion people who cook and heat their homes with biomass fuels and coal.

The latest burden estimates reflect the very significant role air pollution plays in cardiovascular illness and premature deaths – much more so than was previously understood by scientists.

 “WHO Air Quality Guidelines” estimate that reducing annual average particulate matter (PM10) concentrations from levels of 70 μg/m3, common in many developing cities, to the WHO guideline level of 20 μg/m3, could reduce air pollution-related deaths by around 15%.

Useful Links:

Link to the WHO news release:


Link to WHO fact sheet on ambient (outdoor) air quality and health (updated September 2016):


Link to the WHO document ‘Ambient Air Pollution: a global assessment of exposure and burden of disease’:


Link to interactive maps on air pollution levels based on the latest estimates:


Link to WHO’s Air Quality Guidelines, 2005 page (several languages):


Link to WHO’s Urban Ambient (outdoor) Air Pollution Database Summary- Update 2016:


Link to WHO’s Frequently Asked Questions (FAQs) page for Ambient Air Pollution:


Link to WHO’s Burden of Disease from the combined effects of household and Ambient air pollution (2012):


Link to WHO IARC news release regarding outdoor air pollution as a major cause for cancer deaths:


Link to the Technical Report of the Review of evidence on health aspects of air pollution:


Link to WHO’s 2014 FAQ document on the health impact of ambient air pollution:


Link to WHO Europe Region Document on the health effects of particulate matter:


Link to WHO FAQ document on the health effects of air pollution:


Link to WHO’s BreatheLife campaign page:


Link to Breathe Life campaign social media kit (PDF):


Link to WHO’s video related to the Breathe Life campaign:

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