Health and Medical News and Resources

General interest items edited by Janice Flahiff

[News release] Air pollution linked to increased risk of anxiety and stroke

Remember, correlation does not mean cause! See also the rebuttal below

From the 24 March 2015 MedicalExpress item

Air pollution is linked to a higher risk of stroke, particularly in developing countries, finds a study published in The BMJ today. In a second article, new research also shows that air pollution is associated with anxiety.

Stroke is a leading cause of death and kills around 5 million people each year worldwide. Common risk factors include obesity, smoking and . But the effect of the environment, such as, air pollution is uncertain because evidence is lacking.

In a  and meta analysis, a team of researchers from Edinburgh University looked at the association between short term air pollution exposure and stroke related hospital admissions and deaths. In total, they analysed 103  that covered 28 countries across the world.

Gaseous pollutants included in the analysis were , nitrogen dioxide and ozone. In addition, particulate matter was included: PM 2.5 ( less than 2.5 µm in size) and PM 10 (coarse particles less than 10 µm in size).

Results showed an association between carbon monoxide (1.5% increased risk per 1 ppm), sulphur dioxide (1.9% per 10 ppb) and  (1.4% per 10 ppb) and stroke related hospital admissions or death. The weakest association was found for ozone.

Both PM 2.5 and PM 10 were associated with hospital admissions or deaths due to stroke, by 1.1% and 0.3% per 10 µg/m3 increment respectively. The first day of air pollution exposure was found to have the strongest association.

Low- to middle-income countries experienced the strongest associations compared to high-income countries. Only 20% of analysed studies were from low- to middle-income countries – mostly mainland China – despite these countries having the highest burden of stroke.

Both studies were observational and no definitive conclusions can be drawn about cause and effect, and the teams of researchers call for more research.

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March 26, 2015 - Posted by | Public Health | , , , ,

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