The Nurse's Health Study provides information on health, diet and lifestyle of thousands of women across the country. It is a valuable source of information and has been utilized in many different types of studies to learn more about risk factors for various health conditions. One of the recent uses for the study was to try to answer the question of whether pollution has an affect on mental health, particularly anxiety disorders. The results were published in BMJ in March, 2015
Researchers were able to look at health and lifestyle information for over 70,000 women across the country, focusing on exposure to pollution (by proximity to large roads) and incidents of anxiety. According to the researchers, 15 percent of all respondents reported having high anxiety symptoms, such as use of avoidance to minimize symptoms, experiencing fearfulness and a tendency for worry. This number is consistent with other research. The Anxiety and Depression Association of America states that "Anxiety disorders are the most common mental illness in the U.S., affecting 40 million adults, age 18 and older (18 percent of the U.S. population.)"
The results of the study showed that those women who had higher exposure to pollution were more likely to have multiple anxiety symptoms. More recent exposure was associated with higher levels of anxiety. The levels of anxiety seemed to decrease as the time since the exposure increased.
The results of the study show an association, not a link between pollution and anxiety symptoms. It is possible, according to Michael Brauer, in an editorial that accompanied the published study, the reason behind the association may be systemic inflammation, which has been linked to anxiety behaviors in mice and rats. Exposure to pollution can cause systemic inflammation.
According to Melinda Powers, the lead author in the study, the researchers took into account other factors, such as where the person lived (big city or rural area) or whether there were other medical conditions present, such as lung or heart conditions. She believes that it is possible that other types of pollution (such as noise pollution in the city) could also be causing stress and therefore contribute to anxiety symptoms.
Powers looks forward to discovering whether further research will confirm the association between exposure to pollution and anxiety symptoms and believes that further studies should look at possible connections between pollution and other mental health issues.
If pollution is found to be a potential trigger for anxiety symptoms, regulations might help to cut down on the exposure. Individual behaviors, such as avoiding being outdoors on days when the air quality is poor, might also help.
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