There may be more to the “poop and scoop” laws that most districts and municipalities have than we know.  Apart from struggling to wipe dog fecal matter off of your shoe (should the unfortunate situation occur) it turns out that the bacteria from dog fecal matter may be a major source of airborne bacteria in some urban communities.

The study, published in Applied and Environmental Microbiology on July 29 2011, was funded by CIRES Innovative Research Program, the US Environmental Protection Agency, the National Science Foundation, the Howard Hughes Medical Institute and the National Institutes of Health.  The study revealed that of the four Midwestern cities that were in the experiment, two cities had a significant amount of fecal bacteria in the atmosphere.  Dog fecal matter was the most likely source of the bacteria.

Lead author and graduate student of CU-Boulder’s ecology and evolutional biology department and of CU-headquartered Cooperative Institute for Research in Environmental Sciences (also known as CIRES) Robert Bowers said, “We found unexpectedly high bacterial diversity in all of our samples, but to our surprise the airborne bacterial communities of Detroit and Cleveland most closely resembled those communities found in dog poop.

“This suggests that dog poop may be a potential source of bacteria to the atmosphere at these locations.”

The study also included an assistant professor of CU-Boulder’s ecology and evolutionary biology department and CIRES fellow Noah Fierer, an associate professor in CU-Boulder’s chemistry and biochemistry department Rob Knight, as well as Amy Sullivan and Jeff Collet Jr. of Colorado State University and Elizabeth Costello from the Stanford University School of Medicine.

The purpose of the study was to gain a further understanding of what types of microbes are in urban environments.  The team started by analyzing the local atmospheres of the Great Lake region of the United States in both the summer and the winter months.  Three of the selected locations were those of major populations – Cleveland, Detroit, and Chicago – and one location was of Mayville, Wisconsin with a population of fewer than 6000 people.

Close to 100 air samples from a previous study, carried out by the Colorado State University, were used.  The CSU experiment was intended to investigate the impact of biomass burning and the study then looked into the impacts of residential wood burning and prescribed fires on the airborne fine particle concentrations of the United State’s Midwest. That bacteria’s DNA was then compared to the bacteria they had collected in the more recent air samples, and it was then compared against database from well known source such as soil, leaf surfaces, cow, human and dog feces.

The discovery: in Cleveland and Detroit, canine fecal matter was a greater than expected source of bacteria in the atmosphere during the winter months.

As Fierer stated, “We breathe in bacteria every minute we are outside, and some of these bugs may have potential health implications.”  The research team admitted that more research had to be done to come to any finite conclusions, but the team does plan to build up a continental-scale atlas of airborne bacterial communities to further understand the implications of air quality on our health.