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Data Review: How many people die from air pollution?

The diameter of human hair varies, 75µm is a commonly cited reference value https://en.wikipedia.org/wiki/Hair%27s_breadth Heft-Neal, S., Burney, J.,

  • The diameter of human hair varies, 75µm is a commonly cited reference value https://en.wikipedia.org/wiki/Hair%27s_breadth

  • Heft-Neal, S., Burney, J., Bendavid, E. et al. (2018) – Robust relationship between air quality and infant mortality in Africa. Nature 559, 254–258.

  • Burnett, R., Chen, H., Szyszkowicz, M., Fann, N., Hubbell, B., Pope, C. A., Apte, J. S., Brauer, M., Cohen, A., Weichenthal, S., Coggins, J., Di, Q., Brunekreef, B., Frostad, J., Lim, S. S., Kan, H., Walker, K. D., Thurston, G. D., Hayes, R. B., … Spadaro, J. V. (2018) – Global estimates of mortality associated with long-term exposure to outdoor fine particulate matter. Proceedings of the National Academy of Sciences, 115(38), 9592–9597.https://doi.org/10.1073/pnas.1803222115{/ref

    Natural and anthropogenic sources of air pollution

    Most major studies on outdoor air pollution – including the WHO and the IHME estimates – include the death toll from anthropogenic (man-made) and natural sources.

    Anthropogenic sources of outdoor air pollution originate in a variety of human activities: the production of electricity (in particular in coal power plants); the burning of solid fuels (wood, charcoal, coal, crop waste and dung) for cooking and heating in billions of poor households; agriculture; industry; and road transport. 

    The largest source of natural air pollution is airborne dust in the world’s deserts. This form of particulate matter is a very large threat to the health of people in the arid regions of the world. A second major natural source is the smoke from wildfires in forests and grasslands. Additional natural sources are sea spray, pollen, and volcanoes.

    It is possible to reduce natural air pollution to some degree. It is certainly possible to reduce exposure to it – better housing, less time outdoors during periods of high concentration, and filters in the household can all make a difference. 

    But anthropogenic sources of air pollution are of particular interest. We can massively reduce them by changing the technologies that we rely on. We can change the technologies that we rely on to produce electricity, to cook our meals, to heat our homes, to produce our food, and to power our transport. 

    The majority of studies considers both, natural and anthropogenic sources of air pollution. But there are exceptions: Lelieveld et al (2019) is a major recent study of indoor and outdoor air pollution that focuses on anthropogenic sources. According to this study 5.5 million people die prematurely every year due to anthropogenic air pollution. This includes the air pollution caused by agriculture, residential energy use, non-fossil industrial emissions, and fossil fuel burning. 

    These researchers study the impact of burning fossil fuels in particular. They find that the death toll from burning fossil fuels – in power generation, transportation and industry – 3.6 million premature deaths annually. This means that phasing out fossil fuels – and substituting them with clean sources of energy – would avoid an excess mortality of 3.6 million per year; this is more than 6-times the annual death toll of all murders, war deaths, and terrorist attacks combined (the death tolls are shown at the bottom of the chart above and sum up to about 545,000 deaths per year).

    Reference:

    For a big comparative overview of the impact of pollution on human health see: Landrigan PJ, et al. (2018) – The Lancet commission on pollution and health. In The Lancet.

    Study-by-study: The global death toll from air pollution

    Studies that estimate the death toll from outdoor and indoor air pollution

    WHO: 7 million premature deaths per year due to indoor and outdoor air pollution from anthropogenic and natural sources

    The WHO estimates that:

    • 4.2 million die prematurely every year from outdoor (ambient) air pollution.
    • 3.8 million die from indoor air pollution. 
    • 7 million die in total from all sources of air pollution.

    You will notice that the WHO estimates the total death toll to be lower than the sum of indoor and outdoor pollution deaths. This is because the deaths from risk factors are not summable. As the authors explain: “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.”{ref}Quoted from WHO (2021) – Fact sheet: Ambient (outdoor) air pollution

  • Health Effects Institute (2020) – State of Global Air 2020. Special Report. Boston, MA.

    1990: 4,358,000 deaths due to household air pollution from solid fuels –– 2019: 2,314,000 deaths due to household air pollution from solid fuels

    1990: 6,501,000 deaths due to air pollution (both within the household and outdoors) –– 2019: 6,672,000 deaths due to air pollution (both within the household and outdoors)

  • Lelieveld, J., Klingmüller, K., Pozzer, A., Burnett, R. T., Haines, A., & Ramanathan, V. (2019). Effects of fossil fuel and total anthropogenic emission removal on public health and climate. Proceedings of the National Academy of Sciences, 116(15), 7192-7197.

  • The WHO writes “The actual impact of air pollution on health presented here is a conservative figure, as it does not include the separate impacts of health from other air pollutants such as nitrogen oxides (NOx) or ozone (O3), and excludes health impacts where evidence is still limited (e.g. preterm birth or low birth weight).” World Health Organization (WHO) (2016) – Ambient Air Pollution: A Global Assessment of Exposure and Burden of Disease (WHO, Geneva).

  • The WHO writes “Some regions, such as the Eastern Mediterranean and Africa are highly affected by natural desert dust particles. This results in high health burden according to the current methods, which assume natural dust affects health the same way as PM2.5 from other sources.

    The health impacts associated with exposure to dust are not yet fully understood, and are currently treated the same way as those from air pollution in industrialized countries where most of the epidemiological studies have been performed.

    There is a need for a better assessment of the health impacts from natural dust, as it could result in much lower burden than those from anthropogenic particulate matter.” World Health Organization (WHO) (2016) – Ambient Air Pollution: A Global Assessment of Exposure and Burden of Disease (WHO, Geneva).

  • In their 2020 report they report the following figures:

    1990: 2,047,000 ambient PM deaths + 207,400 Ozone = 2,254,400

    2019: 4,141,000 ambient PM deaths + 365,200 Ozone = 4,506,200 as a result of exposure to ambient (outdoor) air pollution.

    Health Effects Institute (2020) – State of Global Air 2020. Special Report. Boston, MA.

  • Lelieveld, J., Evans, J., Fnais, M. et al. (2015) – The contribution of outdoor air pollution sources to premature mortality on a global scale. Nature 525, 367–371 (2015). https://doi.org/10.1038/nature15371

  • Vohra, K., Vodonos, A., Schwartz, J., Marais, E. A., Sulprizio, M. P., & Mickley, L. J. (2021) – Global mortality from outdoor fine particle pollution generated by fossil fuel combustion: Results from GEOS-Chem. In Environmental Research, 195, 110754.

  • A. Vodonos, Y. Abu Awad, J. Schwartz (2018) – The concentration-response between long-term PM2.5 exposure and mortality; A meta-regression approach. In Environ. Res., 166 (2018), pp. 677-689, 10.1016/j.envres.2018.06.021

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