University of Colorado at Boulder, April 23, 2014

The greater prevalence of asthma, allergies and other chronic inflammatory disorders among people of lower socioeconomic status might be due in part to their reduced exposure to the microbes that thrive in rural environments, according to a new scientific paper co-authored by a University of Colorado Boulder researcher.

The article, published in the journal Clinical & Experimental Immunology, argues *that people living in urban centers who have less access to green spaces may be more apt to have chronic inflammation, a condition caused by immune system dysfunction.*

When our immune systems are working properly, they trigger inflammation to fight off dangerous infections, but the inflammation disappears when the infection is gone. However, a breakdown in immune system function can cause a low level of inflammation to persist indefinitely. Such chronic inflammation can cause a host of health disorders.

"Chronic inflammation can lead to all kinds of problems from irritable bowel syndrome to asthma to allergies and even depression," said Christopher Lowry, an associate professor in CU-Boulder's Department of Integrative Physiology and a co-author of the paper. "The rise of chronic inflammation and these associated disorders, especially among people living in the cities of developed countries, is troubling."

"*...exposure to environmental microbes -- such as those found in rural environments, **like farms and green spaces** -- has likely become even more important.*

...In other words, city dwellers of low socioeconomic status might benefit both from being "cleaner" and "dirtier," depending on the context.

Like all people, better hygiene -- like washing their hands more frequently, for example -- could help them avoid crowd infections *while more opportunities to "play in the dirt," like visiting green spaces, could allow their immune systems to come into contact with more beneficial microbes.*

"You don't want the crowd infections," said Lowry. "But you do want to find ways to increase your exposure to 'old friends.' "