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Air Pollution

Air is polluted by the multiple chemicals which are emitted into the atmosphere. Air pollutants can be gases or small particles, which arise from natural and anthropogenic (man-made) sources. Globally, polluted air is recognized as a significant risk to human health. 

 

The World Health Organisation and governments around the world have set safe limits for air pollutants, however research has shown that any level of exposure can cause harm. Beyond the major air pollutants, there are many other compounds that pollute our air and can affect our health. 

 

The amount of air pollution in an area is influenced by the sources of pollutants, the weather, and the landscape.

Where Do They Come From?

Air pollutants can arise from indoor and outdoor (ambient) sources, and outdoor air pollutants can penetrate the indoor environment.  The six major categories of air pollutants include:

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  • Sulphur dioxide: burning of fuel sources such as coal, volcanic eruptions, shipping emissions, oil refineries, industrial boilers. 

  • Carbon monoxide: traffic emissions, burning of fossil fuels, forest fires, indoor biomass burning

  • Particulate matter: burning of fossil fuels, indoor biomass burning, diesel exhaust, dust storms, bush fires, dirt roads, pollen

  • Nitrogen oxides: traffic emission, burning of fossil fuels, kerosene and gas heaters 

  • Ozone: formed when sunlight reacts with nitrogen oxides and volatile organic compounds in the atmosphere

  • Polycyclic aromatic hydrocarbons: fossil fuels, bitumen, burning of biomass, gas heating, volcanic eruptions and traffic emissions

How They Affect You

There is a significant body of evidence to show that air pollution is associated with significant harm to health. The World Health Organisation (Prüss-Üstün et al. 2016) has shown that outdoor air pollution is associated with around 25% of the disease burden from ischaemic heart disease and stroke, 14% of lung cancer burden, and just under 10% of the burden of lower respiratory tract infections and chronic obstructive pulmonary diseases (such as emphysema and chronic bronchitis).

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The health effects from air pollution include:

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Cardiovascular disease
Both indoor and outdoor sources of air pollution are associated with cardiovascular disease. Even in countries with good air quality, small increases in air pollutants have been associated with an increase in elderly people requiring hospitalisation for cardiovascular disease. 

 

Mortality
Several good quality studies have shown that mortality from all causes increases as levels of air pollutants increase. People with cardiovascular disease are at increased risk of mortality from outdoor air pollution. 

 

Birth outcomes
A women’s exposure to both indoor and outdoor air pollution has been linked to adverse outcomes such as lower birthweights, pre-term birth and infant mortality. Second-hand tobacco smoke increases the risk of stillbirth, as well as low birthweight. 

 

Asthma
Research in children has shown an increase risk of hospital presentations due to asthma, and other respiratory conditions, with higher levels of air pollution.

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Chronic obstructive pulmonary disease (COPD)
The WHO have estimated that around 10% of the burden of COPD globally is due to air pollution, most of which occurs indoors. Environmental tobacco smoke and the burning of biomass fuels provides much of the exposure to air pollution associated with COPD. 

 

Respiratory tract infections 
Breathing in air pollutants increases the risk of acute lower respiratory tract infections. Women and children are particularly at risk if they live in a home where biomass (coal, wood, dung) is burnt for cooking and heating. Outdoor air pollution is also a significant contributor to the risk of lower respiratory tract infections.

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Cancer
Epidemiological research has explored the association of air pollution and various cancers. Cancers that have been found to be associated with air pollutants are the following:

  • Lung cancer: Both indoor and ambient air pollution is associated with lung cancer. The World Health Organization estimates that 14% of lung cancers can be attributed to outdoor air pollution and 17% to indoor air pollution. 

  • Cancers of the larynx have been associated with occupational exposure to polycyclic aromatic hydrocarbons and with exposure to particulate matter. 

  • Gastrointestinal cancers: Particulate matter has been associated with a 35-40% higher risk of mortality from various cancers of the gastrointestinal system, in a population exposed to high levels of air pollution. 

  • Breast cancer: The evidence for breast cancer and air pollution is far less clear as published studies have inconsistent reports. There is some evidence that particulate matter is associated with a higher risk of mortality from breast cancer, and that nitrogen dioxide (and other nitrogen oxides) is associated with a slight increase in risk. However a meta-analysis has found that the overall body of evidence is not supportive of an increased risk in breast cancer from exposure to air pollution

  • Bladder and kidney cancers: Fine particulate matter (PM2.5) has been associated with increased risk of both bladder and kidney cancer in a small number of studies.

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Neurological conditions

  • Cognitive decline: Evidence in emerging to show that exposure to air pollution over an extended period may lead to cognitive decline in older persons.

  • Dementia: Particulate matter has been associated with an increased risk of developing dementia in two meta-analyses, however the association with Alzheimer’s disease is less clear. There is some evidence that the negative effects on the cardiovascular system from exposure to particulate matter may lead to the onset of dementia.

  • Mental health: Small increases in the odds of developing depression, anxiety and suicide have been found for exposure to particulate matter, however these results may not be reliable. The most recent meta-analysis of this topic shows the results are not statistically significant.  The link between air quality and mental health must be considered cautiously, and more research is required to further explore the issue.

  • Headache and migraine: All of the major air pollutants (with the exception of polycyclic aromatic hydrocarbons) have been associated with increased odds of hospitalisation for migraine or headache. The increased risk is small, but has been found in several studies globally.

  • Epilepsy: a small number of studies have found an increase in medical support seeking for epilepsy with an increase in the level of ambient air pollution.

  • Autism: The evidence for an association between air pollution and autism remains unclear, with inconsistent findings among studies. Meta-analysis has been conducted, with the most recent showing small increases in the odds of having a child with autism after exposure to fine particulate matter and nitrogen dioxide

How To Protect Yourself

The best way to protect yourself from outdoor air pollutant is to be informed. Most cities around the world publish live-time air quality monitoring. Being aware of the air quality in your city allows you to take action on high pollution days.


Avoid outdoor activities on high pollution days, particularly exercise or other activities that increase respiration rate. Keep windows closed, or only open them for limited periods. On extreme pollution days, or during events such as bush fires, block doors with towels to reduce penetration of the air polluted into the home.


If you have pre-existing heart or lung diseases have an action plan for high pollution days. Ensure you have medications and supplements on hand.  Be aware of any symptoms and seek help early.


Avoid high traffic areas where reasonable. Change walking and cycling routes to quiet streets where safe and try commuting outside of peak hour traffic times. Avoid exercising at night in cold areas where a lot of wood burning stoves/fireplaces are used. Avoid spending excessive time in industrial areas.


To improve indoor air quality, reduce combustion sources in the home. Avoid excessive wood burning, and ensure any stoves or heaters have an adequate and functioning flue. Minimise the burning of incense and mosquito coils (except in areas with significant mosquito-borne disease transmission). Do not allow smoking in the home.


Reduce your production of air pollutants. Choose active transport or public transport rather than driving. Reduce your energy use as much as possible.

Work with a naturopathic doctor / naturopath to help you assess for environmental pollutants and to understand how they may be affecting your health. The information on this website is a guide for ways to protect you and your family from environmental pollutants.  It is not meant to replace advice from a healthcare professional.

3 Essentials

  1. Be aware of the air quality in your city

  2. Clean up sources of air pollution in your home

  3. Do not exercise outside on high pollution days.

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References

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  2. Barnett, A. G., Williams, G. M., Schwartz, J., Best, T. L., Neller, A. H., Petroeschevsky, A. L., & Simpson, R. W. (2006). The Effects of Air Pollution on Hospitalizations for Cardiovascular Disease in Elderly People in Australian and New Zealand Cities. Environmental Health Perspectives, 114(7), 1018-1023. doi:10.1289/ehp.8674

  3. Barnett, A. G., Williams, G. M., Schwartz, J., Neller, A. H., Best, T. L., Petroeschevsky, A. L., & Simpson, R. W. (2005). Air pollution and child respiratory health: a case-crossover study in Australia and New Zealand. Am J Respir Crit Care Med, 171(11), 1272-1278. doi:10.1164/rccm.200411-1586OC

  4. Brauer, M., Lencar, C., Tamburic, L., Koehoorn, M., Demers, P., & Karr, C. (2008). A Cohort Study of Traffic-Related Air Pollution Impacts on Birth Outcomes. Environmental Health Perspectives, 116(5), 680-686. doi:10.1289/ehp.10952

  5. Choi, H., Rauh, V., Garfinkel, R., Tu, Y., & Perera, F. P. (2008). Prenatal exposure to airborne polycyclic aromatic hydrocarbons and risk of intrauterine growth restriction. Environmental Health Perspectives, 116(5), 658-665.

  6. Chun, H., Leung, C., Wen, S. W., McDonald, J., & Shin, H. H. (2020). Maternal exposure to air pollution and risk of autism in children: A systematic review and meta-analysis. Environ Pollut, 256, 113307. doi:10.1016/j.envpol.2019.113307

  7. Di, Q., Wang, Y., Zanobetti, A., Wang, Y., Koutrakis, P., Choirat, C., . . . Schwartz, J. D. (2017). Air Pollution and Mortality in the Medicare Population. New England Journal of Medicine, 376(26), 2513-2522. doi:10.1056/NEJMoa1702747

  8. Farmer, S. A., Nelin, T. D., Falvo, M. J., & Wold, L. E. (2014). Ambient and household air pollution: complex triggers of disease. American journal of physiology. Heart and circulatory physiology, 307(4), H467-H476. doi:10.1152/ajpheart.00235.2014

  9. Frumkin, H. (2016). Environmental health: from global to local: John Wiley & Sons.

  10. Hahad, O., Lelieveld, J., Birklein, F., Lieb, K., Daiber, A., & Münzel, T. (2020). Ambient Air Pollution Increases the Risk of Cerebrovascular and Neuropsychiatric Disorders through Induction of Inflammation and Oxidative Stress. International journal of molecular sciences, 21(12), 4306. doi:10.3390/ijms21124306

  11. IARC Working Group on the Evaluation of Carcinogenic Risks to Humans. (2016). Outdoor Air Pollution: IARC Monographs on the Evaluation of Carcinogenic Risks to Humans.

  12. Kampa, M., & Castanas, E. (2008). Human health effects of air pollution. Environmental Pollution, 151(2), 362-367. doi:https://doi.org/10.1016/j.envpol.2007.06.012

  13. Kim, H.-B., Shim, J.-Y., Park, B., & Lee, Y.-J. (2018). Long-Term Exposure to Air Pollutants and Cancer Mortality: A Meta-Analysis of Cohort Studies. International journal of environmental research and public health, 15(11), 2608. doi:10.3390/ijerph15112608

  14. Lam, J., Sutton, P., Kalkbrenner, A., Windham, G., Halladay, A., Koustas, E., . . . Woodruff, T. (2016). A Systematic Review and Meta-Analysis of Multiple Airborne Pollutants and Autism Spectrum Disorder. PLoS One, 11(9), e0161851. doi:10.1371/journal.pone.0161851

  15. Nuvolone, D., Petri, D., & Voller, F. (2018). The effects of ozone on human health. Environmental Science and Pollution Research, 25(9), 8074-8088. doi:10.1007/s11356-017-9239-3

  16. Prüss-Üstün, A., Wolf, J., Corvalán, C., Bos, R., & Neira, M. (2016). Preventing disease through healthy environments: a global assessment of the burden of disease from environmental risks: World Health Organization.

  17. Shah, A. S., Lee, K. K., McAllister, D. A., Hunter, A., Nair, H., Whiteley, W., . . . Mills, N. L. (2015). Short term exposure to air pollution and stroke: systematic review and meta-analysis. Bmj, 350, h1295. doi:10.1136/bmj.h1295

  18. Tsai, T. L., Lin, Y. T., Hwang, B. F., Nakayama, S. F., Tsai, C. H., Sun, X. L., . . . Jung, C. R. (2019). Fine particulate matter is a potential determinant of Alzheimer's disease: A systemic review and meta-analysis. Environ Res, 177, 108638. doi:10.1016/j.envres.2019.108638

  19. Wong, C. M., Tsang, H., Lai, H. K., Thomas, G. N., Lam, K. B., Chan, K. P., . . . Thach, T. . (2016). Cancer Mortality Risks from Long-term Exposure to Ambient Fine Particle. Cancer Epidemiology Biomarkers & Prevention, 25(5), 839. doi:10.1158/1055-9965.EPI-15-0626

  20. Yin, P., He, G., Fan, M., Chiu, K. Y., Fan, M., Liu, C., . . . Zhou, M. (2017). Particulate air pollution and mortality in 38 of China’s largest cities: time series analysis. 356, j667. doi:10.1136/bmj.j667 %J BMJ

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