COLORADO, March 14 ― New US research has found that exposure to air pollution could be affecting our gut bacteria, which could be increasing our risk of chronic illnesses such as obesity, diabetes, and gastrointestinal disorders.

Carried out by researchers at the University of Colorado Boulder, the new study recruited 101 young adults in Southern California and analysed their fecal samples to look at their gut microbiome, which is the community of bacteria, viruses and fungi which live mainly in our small and large intestines.

The researchers also analysed data gathered from air-monitoring stations near the participants' addresses to calculate their exposure to ozone (which is formed when emissions from vehicles, power plants, chemical plants and other sources are exposed to sunlight), particulate matter (or PM10, which are particles with a diameter of 10 micrometres or smaller) and nitrous oxide (which is a byproduct of burning fossil fuel) over the past year.

The findings, published online in the journal Environment International, showed that out of all of the pollutants measured in the study, ozone by far had the biggest impact on the gut.


The researchers found that ozone accounted for about 11 percent of the variation seen in the gut microbiome of the participants and appeared to have a bigger effect than gender, ethnicity or even the participants' diet.

Moreover, those who were exposed to higher levels of this pollutant had less variety of bacteria living in their gut and more of the species of bacteria which are associated with obesity and disease called Bacteroides caecimuris.

“This is important since lower (bacteria) diversity has been linked with obesity and Type 2 diabetes,” noted senior author Tanya Alderete.


The study is the first to link air pollution to changes in the structure and function of the human gut microbiome. However, Alderete pointed out that, “We know from previous research that air pollutants can have a whole host of adverse health effects,” with previous research linking pollution with Type 2 diabetes, weight gain and inflammatory bowel diseases.

“The takeaway from this paper is that some of those effects might be due to changes in the gut.”

“Ozone is likely changing the environment of your gut to favour some bacteria over others, and that can have health consequences,” said Alderete.

The researchers did note that their sample size was small and the study did have some limitations, such as taking stool samples just once. However, Alderete added that, “A lot of work still needs to be done, but this adds to a growing body of literature showing that human exposure to air pollution can have lasting, harmful effects on human health.” ― AFP-Relaxnews