Updated August 12, 2015.

We constantly interact with the environment around us. What happens on the inside of our bodies  is directly related to what is going on in the environment outside of our bodies. That is because we are continually breathing in the air that surrounds us- including whatever materials happen to be present in that air. Air pollution and contamination have a known and well-understood impact on our respiratory health.

And, interestingly, the noxious particles in the air we breathe have also been shown to contribute to the risk of stroke.

 

Does Pollution Have an Effect on Stroke?

Air pollution varies throughout the world- both in the levels of contamination and in the types of pollutants that are present in different settings. Researchers from numerous regions around the world have examined the impact of air pollution on stroke and the results are surprising.

A recent scientific article published in the September 2014 issue of the Sao Paulo Medical Journal reported on the relationship between stroke and air pollution in San Paulo, Brazil, a city considered to have low air pollution. The results demonstrated that exposure to particulate matter and sulfur dioxide air pollutants increased the risk of stroke deaths by 7%-10%. Similarly, an investigation conducted in Taipei, Taiwan determined that a high level of fine particles in the air was correlated with an increase in the number of hospitalizations for hemorrhagic strokes.

Numerous scientific research analysis from different cities, populations and settings show similar findings, all of which which suggest that pollution exposure produces a small to moderate increase in the incidence of stroke.

What Types of Stroke are Associated with Air Pollution?

An analysis conducted in London sought to differentiate the specific types of strokes associated with exposure to high levels of nitric oxide and particulate matter. The study determined that patients were indeed more likely to have strokes, but that the strokes tended to be mild to moderate strokes, not severe strokes.

How Long Does it Take for Pollution to Cause a Stroke?

Another study in Brazil specifically identified ozone exposure and same day exposure to particulate matter and sulfur dioxide as a risk for stroke requiring hospital admission. A Meta-analysis that examined a total of 34 separate studies on this subject, published in the August 2014 International Journal of Cardiology confirmed a short-term relationship between exposure to air pollution and the occurrence of stroke.

Is the Damage Permanent?

The good news is that the Meta-analysis specifically noted that pollution has only a transient (short -term) effect on stroke risk, which probably means that the risk of stroke related to air pollution may not last for long after the exposure to air pollutants drops. So getting some fresh air can help reverse the stroke risk of pollution!

 

Sources:

Amancio CT, Nascimento LF, Environmental pollution and deaths due to stroke in a city with low levels of air pollution: ecological time series study, Sao Paulo Medical Journal, September 2014

Nascimento LF, Francisco JB, Patto MB, Antunes AM, Environmental pollutants and stroke-related hospital admissions, Cad Saude Publica, July 2014

Chiu HF, Chang CC, Yang CY , Relationship between hemorrhagic stroke hospitalization and exposure to fine particulate air pollution in Taipei, Taiwan, Journal of Toxicology and Environmental Health, August 2014

Maheswaran R, Pearson T, Beevers SD, Campbell MJ, Wolfe CD, Outdoor air pollution, subtypes and severity of ischemic stroke - a small-area level ecological study, International journal of Health Geographics, July 2014

Yang WS, Wang X, Deng Q, Fan WY, Wang WY, An evidence-based appraisal of global association between air pollution and risk of stroke, International Journal of Cardiology, August 2014

Jacqui Wise, Researchers find no clear link between air pollution and heart attack or strokes, British medical Journal, June 2014