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Pollution linked to stroke and anxiety

Fri, 27th Mar 2015

Chris Smith

Bad air days correlate with higher anxiety levels and are also linked to strokes, new research has revealed. Pollution

The potential health consequences of exposure to airborne pollution have been highlighted for many years. The WHO attributes one death in every eight to air pollution, and other recent evidence suggests a role of pollution in the development of diabetes, pre-term birth risk and low birthweight.

Now two papers in the British Medical Journal this week add further weight to the argument, demonstrating a link to stroke risk and anxiety.

One of the studies combined the data from 103 independent other studies carried out in 28 countries and logged over 6 million data points. Bad air days, it concluded, are significantly associated with hospital admissions for stroke.

In a second study, which used data from over 70,000 nurses who have been followed up over a long period of time, pollution exposure was significantly linked to anxiety. Greater exposure to smaller pollutant particles, referred to as PM2.5, the team found, was associated with increased reported anxiety scores in the study subjects, an effect that remained even when effects such as stroke risk where controlled for.

The findings tally with previous observations showing an association between pollution and suicide risk. However, the researchers acknowledge in their BMJ report that there are some confounding variables, like noise, which may also be playing a role.People exposed to the greatest levels of pollution may be exposed to greater noise pollution too. That said, fine airborne pollutant particles have been shown to trigger inflammatory responses in the body, and it has been shown that systemic inflammation can lead to mood disorders including anxiety and depression.

The findings are therefore biologically plausible although, as an accompanying editorial emphasises, further study is warranted to establish and confirm how these links occur.


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Correlation is not proof of causation.Where do you find lots of pollution? In cities. where do you find stress and anxiety? In crowds. Where do you find crowds? In cities. alancalverd, Fri, 27th Mar 2015

Alan - with respect, it does say "associated with" and reference is made to the confounders. But, if you read the paper you'll see that they have actually attempted to control for many of these variables, suggesting that the findings are robust and biologically plausible. chris, Sat, 28th Mar 2015

Interesting studies Chris. Now I just have this nagging feeling left, that as long as we don't reach a 'critical thresh hold', related to the balance between what a 'individual' need to have done, or if you like society expects him to have done, before his or her demise, nothing will be done, except more studies. That 'critical thresh hold' should probably have some parameters being 'instinctive' as in 'ageless', other dynamically introduced by different ways of living through history. It would explain a lot of it existed, as we do react even if it comes late. Environmental causes, as our general pollution of the Earth is a very slow mechanism humanly seen, though. So by the time global warming will be in full gear, I'm afraid we will be to late reacting, to really change anything. I hope I'm wrong. yor_on, Sat, 28th Mar 2015

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