Toxic Air Pollution | Detox Health Blog

Smoggy Days Cause Mental Haze, Strokes


If you like to peruse those “Best Places to Live” articles that regularly appear in travel magazines, you might want to start paying attention to what the articles say regarding air quality in your fantasy locations. Although your ideal spot may have great recreational opportunities, perfect climate, and superb access to medical care, if it also has a high level of air pollution, it probably should be scratched from your list. That’s because two new studies, just published in The Archives of Internal Medicine, reveal that air pollution causes far more mischief than previously thought.1

The new studies show that exposure to even moderate levels of air pollution can trigger strokes and rapid cognitive decline. And it’s not just long-term exposure that ups the danger; short-term exposure over the course of a single day increases risk by a significant margin. Although previous research has confirmed that pollution triggers cardiovascular and respiratory damage, it’s turning out that polluted air circulates throughout the system and wreaks havoc throughout the body and brain.2

The first study, out of Brown University in Rhode Island, reviewed medical records of more than 1700 women living in the Boston area who had suffered an ischemic stroke. That’s the type of stroke that occurs when the main artery leading to the brain gets blocked — the most common type. According to the study, the risk of ischemic stroke rose by 34 percent on days when pollution nudged upward from “Good” to “Moderate.” Note: we’re not even talking about high levels of pollution here — just levels a bit elevated, though still acceptable by EPA standards. Take note of that, Beijing residents!3

“At levels that the Environmental Protection Agency says are safe, we’re seeing real health effects,” said Dr. Gregory A. Wellenius, the lead author of the study.4 “We saw these effects within 12 to 14 hours of when pollution levels went up.”

The study didn’t measure the impact of high levels of pollution since the research took place in Boston where smog rarely reaches so-called hazardous elevations. But, it turns out that the rise in risk was dose related, meaning that for every 6.4 µg/m3 increase in particulate matter, the risk of stroke rose another 11 percent.

And so it seems obvious that the higher the smog levels, the higher the risk, and very high smog levels that exceed EPA limits would indicate very high stroke-risk conditions. Also, as noted above, the risk increase occurs almost immediately upon exposure, peaking within 12 to 24 hours of breathing in the polluted air. The news makes it seem downright foolish to ignore the “stay inside” warnings on high-smog days, or even on moderate-smog days if you have conditions that put you at risk for stroke. It turns out, by the way, that the pollution emanating from car fumes has the most deleterious consequences and the most direct impact on stroke. And as Jon Barron noted five years ago, living near busy roads increases your risk of developing atherosclerosis — which itself puts you at greater risk of stroke. Makes the old real estate selling point “convenient to the highway” not so compelling, after all.

In the second study, researchers from Rush University in Chicago studied medical records of nearly 20,000 elderly women between the ages of 70 and 81. The participants had received biannual cognitive tests over a ten-year period. The tests measured their thinking skills, verbal memory, working memory, and attention. The researchers then looked at the geographic locale of each participant, examining the short- and long-term levels of pollution in that region both in the month preceding each cognitive test, as well as for the entire 14-year period preceding the study.

The results showed that the smoggier the location the participant lived in over the long-run, the faster the rate of cognitive decline they experienced. And this relationship held whether the source of pollution was fine or course particulate matter — meaning all types of smog can bring about loss of marbles, not just automobile fumes. According to study author Dr. Jennifer Weuve, in addition to car exhaust, the pollution can come from “…burning wood, burning fuels, burning coal, another source of dust… and that dust can come from agricultural sources. It can come from forest fires, and it can also come from industrial processes such as crushing or grinding operations, which is also how we get dust in rural areas when we think of trucks going up gravel roads.” In other words, if you live on a dusty dirt road with plenty of traffic, you live in a high-fume locale.

As with the stroke study, the cognitive-decline study also found a dose-related relationship, meaning that each 10 µg per cubic meter increase in concentration of particulate matter over the long term resulted in about two years of aging. According to Dr. Weuve, that’s approximately the difference between living in Boston versus the slightly more polluted Chicago. She says that the problem with particulate matter is that it gets into the brain and causes inflammation, and all evidence indicates that swelling is a trigger for dementia — which is yet another reason for getting on a regimen of proteolytic enzymes, which specifically reduce systemic inflammation on multiple levels.

Shaving a few years off of your mental acuity may not seem like such a high price to pay when you’re young and enjoying all the amenities present in your polluted living or working space, but remember that the two years may multiply to four or six years depending on just how much smog you live with. And also remember that it’s not just smarts that get compromised by smog, but also, physical health suffers, too.

The bad news is that no matter where you live, you probably get exposed to some degree of pollution. The good news is, that if you’re willing, you can choose a comparatively less polluted place to live, take a good antioxidant formula and get an air filtration system in place, and heed the warnings to stay inside when the smog grows thick. Also, you can work for a cleaner environment. According to Dr. Wellenius of the stroke study, reducing air pollution levels just 20 percent, “would have prevented about 6,000 of the 184,000 hospitalizations for stroke in the Northeast region” in 2007 alone.


1 Paddock, Catharine. “Air Pollution Tied to Cognitive Decline, Stroke.” 15 February 2012. Medical News Today. 20 February 2012. <>

2 Flatow, Ira. “Air Pollution Ups Risk of Stroke, Impaired Memory.” 17 February 2012. NPR. 20 February 2012. <>

3 Adrienne Mong. “Beijing residents call foul over the air.” 9 Nov 2011. MSNBC. (Accessed 20 Feb 2012.) <>

4 O’Connor, Anahad. “Air Pollution Linked to Heart and Brain Risks.” 15 February 2012. The New York Times. 20 February 2012. <>

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