Is this why so many city dwellers have health issues? Air pollution found to radically increase stress hormones and alter metabolism

There really is something to be said for getting out into the fresh country air for a day. There is a tangible difference in how much better one feels in the country than in the city, especially if you have a very demanding job. While the stresses and strains of fast-paced city life may partly explain this feeling, new research by Dr. Haidong Kan and colleagues from Fudan University in Shanghai, China, indicates that the air pollution found in industrialized cities also causes a spike in stress hormones, resulting in the development of diseases like stroke, diabetes and heart disease, and ultimately shortening lifespan.

Reuters is reporting that the study, which was published in the journal Circulation, focused specifically on the long-term health effects of the inhalation of particulate matter (PM) smaller than 2.5 micrometers in diameter from industrial pollution. While the World Health Organization (WHO) recommends that the level of 2.5 PM be kept below 10 to maintain the health of city residents, in some cities these levels exceed 50.

For their study, researchers divided 55 healthy college students from the city of Shanghai, which has moderate pollution levels compared to other Chinese cities, into two groups. Functioning air purifiers were placed in the dorm rooms of one group, while non-working units were placed in the remaining students’ rooms for nine days. After a 12-day gap the machines were swapped and another nine-day test was conducted. The participants were given blood and urine tests at the end of each nine-day period to determine their exposure to PM.

Interestingly, the scientists determined that even over just the nine-day period, levels of the stress hormones cortisone, cortisol, norepinephrine and epinephrine rose when the participants were exposed to the dirtier air. Their blood sugar, amino acid, fatty acid and lipid levels also rose, as did their blood pressure levels. The students also exhibited other indicators of molecular body tissue stress. This combination of stressors would likely lead to heart disease, diabetes and other health problems over time. (Related: Discover other ways in which our environment affects our health at Environ.news)

“This research adds new evidence on how exposure to PM could affect our bodies, which may (ultimately) lead to higher cardiovascular risk,” Dr. Kan told Reuters Health. “Our result may indicate that particulate matter could affect the human body in more ways than we currently know. Thus, it is increasingly necessary for people to understand the importance of reducing their PM exposure.” (Related: Deep breathing of polluted air puts bike riders at higher risk of lung cancer and strokes.)

Exposure to pollution may not be the only way in which cities can negatively impact our health.

A 2014 study by researchers from the Central Institute of Mental Health in Mannheim, Germany, set out to determine the impact of stress on city dwellers’ brains. They discovered that in comparison to their country cousins, city slickers did not handle stress well at all.

The researchers purposely induced stress in study participants and then studied its effects on two areas of the brain: The amygdalas and the perigenual anterior cingulate cortex (pACC).

The Guardian explains their findings:

The amygdalas are known to be involved in assessing threats and generating fear, while the pACC in turn helps to regulate the amygdalas. In stressed citydwellers, the amygdalas appeared more active on the scanner; in people who lived in small towns, less so; in people who lived in the countryside, least of all.

And something even more intriguing was happening in the pACC. … Again, those with rural childhoods showed the least active pACCs, those with urban ones the most. In the urban group moreover, there seemed not to be the same smooth connection between the behaviour of the two brain regions that was observed in the others. An erratic link between the pACC and the amygdalas is often seen in those with schizophrenia too. And schizophrenic people are much more likely to live in cities.

Clearly, living in the city is not the best choice when it comes to either our mental or physical health. For those of us who have no option, however, it is important to get out into the country and breathe that fresh, clean air as often as possible.

Sources include:

Reuters.com

TheGuardian.com