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WHO links 7 million premature deaths annually to air pollution; 12.5% of total global deaths

The World Health Organization now estimates that in 2012 around 7 million people died—one in eight (12.5%) of total global deaths—as a result of air pollution exposure. This new estimate more than doubles previous estimates and confirms that air pollution is now the world’s largest single environmental health risk, according to WHO, which is the directing and coordinating authority for health within the United Nations system.

WHO says that the new data reveal a stronger link between both indoor and outdoor air pollution exposure and cardiovascular diseases, such as strokes and ischemic heart disease (an insufficient supply of blood—and thus oxygen—to the heart), as well as between air pollution and cancer. This is in addition to air pollution’s role in the development of respiratory diseases, including acute respiratory infections and chronic obstructive pulmonary diseases.

The new estimates are not only based on more knowledge about the diseases caused by air pollution, but also upon better assessment of human exposure to air pollutants through the use of improved measurements and technology. This has enabled scientists to make a more detailed analysis of health risks from a wider demographic spread that now includes rural as well as urban areas.

Regionally, low- and middle-income countries in the WHO South-East Asia and Western Pacific Regions had the largest air pollution-related burden in 2012, with a total of 3.3 million deaths linked to indoor air pollution and 2.6 million deaths related to outdoor air pollution—5.9 million deaths in total.

Cleaning up the air we breathe prevents noncommunicable diseases as well as reduces disease risks among women and vulnerable groups, including children and the elderly. Poor women and children pay a heavy price from indoor air pollution since they spend more time at home breathing in smoke and soot from leaky coal and wood cook stoves.

—Dr. Flavia Bustreo, WHO Assistant Director-General Family, Women and Children’s Health

Included in the assessment is a breakdown of deaths attributed to specific diseases, underlining that the vast majority of air pollution deaths are due to cardiovascular diseases as follows:

Outdoor and indoor air pollution-caused deaths – breakdown by disease. Data: WHO. Click to enlarge.

The new estimates are based on the latest WHO mortality data from 2012 as well as evidence of health risks from air pollution exposures. Estimates of people’s exposure to outdoor air pollution in different parts of the world were formulated through a new global data mapping. This incorporated satellite data, ground-level monitoring measurements and data on pollution emissions from key sources, as well as modeling of how pollution drifts in the air.

After analyzing the risk factors and taking into account revisions in methodology, WHO estimates indoor air pollution was linked to 4.3 million deaths in 2012 in households cooking over coal, wood and biomass stoves.

The new estimate is explained by better information about pollution exposures among the estimated 2.9 billion people living in homes using wood, coal or dung as their primary cooking fuel, as well as evidence about air pollution’s role in the development of cardiovascular and respiratory diseases, and cancers.

In the case of outdoor air pollution, WHO estimates there were 3.7 million deaths in 2012 from urban and rural sources worldwide.

Many people are exposed to both indoor and outdoor air pollution. Due to this overlap, mortality attributed to the two sources cannot simply be added together, hence the total estimate of around 7 million deaths in 2012.

Later this year, WHO will release indoor air quality guidelines on household fuel combustion, as well as country data on outdoor and indoor air pollution exposures and related mortality, plus an update of air quality measurements in 1,600 cities from all regions of the world.

Outdoor pollution. WHO estimates that some 80% of outdoor air pollution-related premature deaths were due to ischemic heart disease and strokes, while 14% of deaths were due to chronic obstructive pulmonary disease or acute lower respiratory infections; and 6% of deaths were due to lung cancer.

Some deaths may be attributed to more than one risk factor at the same time. For example, both smoking and ambient air pollution affect lung cancer. Some lung cancer deaths could have been averted by improving ambient air quality, or by reducing tobacco smoking.

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. (Earlier post.) 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 3.7 million premature deaths worldwide per year 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.

People living in low- and middle-income countries disproportionately experience the burden of outdoor air pollution with 88% (of the 3.7 million premature deaths) occurring in low- and middle-income countries, and the greatest burden in the WHO Western Pacific and South-East Asia regions. The latest burden estimates reflect the very significant role air pollution plays in cardiovascular illness and premature deaths—much more so than was previously thought.

The 2005 “WHO Air quality guidelines” offer global guidance on thresholds and limits for key air pollutants that pose health risks. The Guidelines indicate that by reducing particulate matter (PM10) pollution from 70 to 20 micrograms per cubic meter (μg/m3), can cut air pollution-related deaths by around 15%.

The Guidelines apply worldwide and are based on expert evaluation of current scientific evidence for particulate matter (PM); ozone (O3); nitrogen dioxide (NO2); and sulfur dioxide (SO2), in all WHO regions.

  • PM. PM affects more people than any other pollutant. The major components of PM are sulfate, nitrates, ammonia, sodium chloride, black carbon, mineral dust and water. It consists of a complex mixture of solid and liquid particles of organic and inorganic substances suspended in the air. The most health-damaging particles are those with a diameter of 10 microns or less, (≤ PM10), which can penetrate and lodge deep inside the lungs. Chronic exposure to particles contributes to the risk of developing cardiovascular and respiratory diseases, as well as of lung cancer.

    Air quality measurements are typically reported in terms of daily or annual mean concentrations of PM10 particles per cubic meter of air volume (m3). Routine air quality measurements typically describe such PM concentrations in terms of micrograms per cubic meter (μg/m3). When sufficiently sensitive measurement tools are available, concentrations of fine particles (PM2.5 or smaller), are also reported.

    There is a close, quantitative relationship between exposure to high concentrations of small particulates (PM10 and PM2.5) and increased mortality or morbidity, both daily and over time. Small particulate pollution have health impacts even at very low concentrations—indeed, no threshold has been identified below which no damage to health is observed. Therefore, the WHO 2005 guideline limits aimed to achieve the lowest concentrations of PM possible.

    WHO PM Guideline Values
    PM2.5 10 μg/m3 annual mean 25 μg/m3 24-hour mean
    PM10 20 μg/m3 annual mean 50 μg/m3 24-hour mean

    In addition to guideline values, the Air Quality Guidelines provide interim targets for concentrations of PM10 and PM2.5 aimed at promoting a gradual shift from high to lower concentrations.

  • Ozone. Ozone is a major factor in asthma morbidity and mortality. Ozone at ground level—not to be confused with the ozone layer in the upper atmosphere—is one of the major constituents of photochemical smog. It is formed by the reaction with sunlight (photochemical reaction) of pollutants such as nitrogen oxides (NOx) from vehicle and industry emissions and volatile organic compounds (VOCs) emitted by vehicles, solvents and industry. As a result, the highest levels of ozone pollution occur during periods of sunny weather.

    The current guideline value is 100 μg/m3 8-hour mean. This value was reduced from the previous level of 120 µg/m3 based on recent conclusive associations between daily mortality and lower ozone concentrations.

  • Nitrogen dioxide and sulfur dioxide. Nitrogen dioxide can play a role in asthma, bronchial symptoms, lung inflammation and reduced lung function. The major sources of anthropogenic emissions of NO2 are combustion processes (heating, power generation, and engines in vehicles and ships).

    Epidemiological studies have shown that symptoms of bronchitis in asthmatic children increase in association with long-term exposure to NO2. Reduced lung function growth is also linked to NO2 at concentrations currently measured (or observed) in cities of Europe and North America.

    Guideline values are 40 μg/m3 annual mean and 200 μg/m3 1-hour mean.

  • Sulfur dioxide. Sulfur dioxide can also play a role in asthma, bronchial symptoms, lung inflammation and reduced lung function. SO2 is produced from the burning of fossil fuels (coal and oil) and the smelting of mineral ores that contain sulfur. The main anthropogenic source of SO2 is the burning of sulfur-containing fossil fuels for domestic heating, power generation and motor vehicles.

    Studies indicate that a proportion of people with asthma experience changes in pulmonary function and respiratory symptoms after periods of exposure to SO2 as short as 10 minutes.

    Guideline values are 20 μg/m3 24-hour mean, 500 μg/m3 10-minute mean. The (2005) revision of the 24-hour guideline for SO2 concentrations from 125 to 20 μg/m3 was based on known association of health effects with much lower levels of SO2 than previously believed.



Air pollution is killing more and more people at a higher yearly rate and is only surpassed (so fasr) by WWII. If the increasing trend continues, it will soon become the all time number one killer.

We may have to stop BURNING wood, agriculture, industrial and domestic residues and all fossil and bio-fuels in power plants and ICEVs.

If we don't develop safer ways, many more will get sick and die from man made pollution.


It's been many times that i said to begin hydrogen cars commercialization to lessen air pollution. When they gonna give me for free a hydrogen car so I will be showing the way ? Hydrogen is way less polluting than gasoline, about 100x.

Nick Lyons

The big killers are coal power plants and indoor cooking with wood, dung, coal, etc. The world needs new paradigm cheap, safe nuclear power and a huge investment in electrification throughout the developing world.


Nick, as someone who watches with great frustration every time the industrialized world hides under the bedsheets at the mention of "nuclear", I am somewhat in agreement on the cheap nuclear power dream. But our desire for a "new paradigm" isn't coming fast enough to eliminate "dirty" but readily available fuel use by desperate people.

Think of the family in some miserably poor place, living in a cramped space with people huddled one to every available 2 or 3 square meter of living space. Without heat they die. But here comes a WHO doctor telling the head of household they are risking long-term respiratory disease, and we want them to stop burning cheap lignite in their crude stove to survive. Without an immediate solution, we are doing a blood lipid screening on a starving patient, telling him he really shouldn't eat the goat's milk products and occasional meat because it could lead to long-term circulatory problems. He will rightly tell Dr. WHO to GTFO.

Even coal-fired facilities creating the mass electrification you (correctly) desire are a far better alternative in the short run. You can put one up in two years, and burn coal in a modern co-gen facility far more cleanly than on a household basis while the right nuclear solution is brought to bear. PV is lovely, and do it if you'd like, but with limited rooftop area and winter intermittency it can't approach reliable large-scale power. (Witness even the advanced Germany, whose renewable investments are unprecedented, building TEN new coal-fired plants in the next two years


as the enormous wind and solar "resources" cannot run on hope and pure intent when Nature falls short.)


World population growing at a much faster rate (specially in the last 70 years or so) is certainly part of the higher pollution problem.

By 1927, world population growth had already increased to 1B/123 years. By 2010 the rate had increased 10X to 1B/12 years and reached a total of 7 B.

If the very high population growth rate of the last 70 years keeps up, the world could have 16 billion people by 2100.

After 2100, the world will probably run out of fossil fuels to burn and space to grow enough food. Both population and pollution may start to go down to a sustainable level of (10B to 12B?).


Much more than 90% of vehicle PM10 comes from road and tyre contact (for new vehicles, the share is much higher). The heavier the vehicle, the more PM10 you get. If you increase the weight of a car by 100 kg by adding batteries, such a car might be worse than a conventional ICE car regarding PM10. In particular, if we compare an EV with a diesel car with DPF or a gasoline car with GPF, the EV is not an apparent winner. The statement in the last issue of Engine Technology: “The engineers at TÜV Nord actually told me that the exhaust is cleaner than the ambient air”, require some contemplation (see link below). Should we ban such cars? Cars that clean the air… Well, that is if we only focus on the engine inlet and outlet and look at the net effect on PM (and PN, if we like).

For the moment, we cannot control emissions from road and tyre contact. There is simply no solution available. This also applies to rail traffic, albeit the lower PM emission per passenger km. With poor ventilation in the tunnels, the air in subways can be 10x more polluted than on the busy street above. However, EU’s ambient air quality limits do not apply down there, so it is not considered a problem; for the moment. We could just put a sign on the subway entrance: “Abandon hope, all ye who enter here”, as in Dante’s inferno. In the next few years, we will control exhaust emissions from new cars and replace the old dirty ones. As said, however, exhaust is not the only source. The biggest problem on a longer term horizon is that cities are too large and too dense. Put too many people in one spot and you will get problems with local pollution, no matter what you try to do to prevent this from happening.



I fully agree with you that we also have to deal with overpopulation…


If you don't have a billion dollars you just don't matter. You will not be allowed to live in the post resource world anyway.

Nick Lyons

The proven solution to excessive birthrates is economic development and the empowerment of women. In the developed world, children are a net economic cost and are much more likely to survive to adulthood, so birthrates go down. And when women have more education and control over their lives, birthrates go down. Electricification is key to development, but it must be cheap enough--renewables aren't going to work for developing economies. The developing world needs cheap, clean nuclear power.


Pollution is associated with many early fatalities. More and more babies are born with brain deformities such as autism and other critical internal and external body irregularities. They are not all included in the 7 million/year.

Roger Pham

The West has mastered the technologies necessary for pollution control, however, somehow the rest of the world have chosen NOT to employ those technologies...perhaps due to cost issue. The air pollution in Beijing is perhaps 10-100x safe level...yet, economic growth from dirt-cheap goods made for exporting must continue, or the people will revolt due to lack of jobs and hence threatening the legitimacy of the Party in power...Meanwhile, elsewhere in the West, jobs are being lost and gov. debts are piling up due to eroding tax base...

Yet, no one dares to put those two facts together to save lives in the East from pollution AND saving jobs from the West due to unfair cost advantage in the East due to undue pollution from dirt-cheap manufacturing practices...

Technologies are available to eliminate air and water and environmental pollutions...Economic and Political reasons are what kept them from being deployed elsewhere in the where.

Henry Gibson

One hundred percent nuclear electricity is possible in developed countries now, which leaves coal and natural gas available to convert into liquid fuels for automobiles which makes efficient liquid fuels available in more countries as well as making electricity available where wood was used before. Fifty watts is enough for any household for an efficient electric cooker. Buried plastic covered sodium filled tubes are low cost conductors that few would want to steal a second time. ..HG..

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