Catching Pneumonia from your Car


A form of bacteria responsible for respiratory illness – including the deadly pneumonia known as Legionnaire’s disease – may be able to grow in windshield washer fluid used in cars.

A recent study has revealed that the bacteria Legionella, commonly found in fresh water, is able to survive in certain automobile windshield washer fluids and can grow in washer fluid reservoirs, potentially exposing people to the bacteria.

The study was conducted by Otto Schwake, an Arizona State University student pursuing a doctoral degree in microbiology under the supervision of Morteza Abbaszadegan, a professor in the School of Sustainable Engineering and the Built Environment. Schwake examined windshield washer fluid from Arizona school buses, revealing frequent contamination with high levels of Legionella and demonstrating that washer fluid spray can release potentially dangerous numbers of these bacteria into the air. These results suggest that automobiles may serve as a source of transmission for Legionella infections.

This research was performed at the Tempe, AZ campus of ASU in Abbaszadegan’s Environmental Microbiology Lab, with field samples collected from buses belonging to a school district in central Arizona. Funding for the project came through the National Science Foundation Water and Environmental Technology Center at ASU. Schwake will give a presentation on this work at the 114th General Meeting of the American Society in Boston, MA on Tuesday, May 20 from 2:30-2:45 in the symposium session “We Are Not Alone: Microbial Revelations of the Built Environment.”

Although windshield washer fluid is not normally associated with spreading disease, this project was begun after a series of epidemiological studies found motor vehicle use to be associated with increased risk for Legionnaires’ disease. One such study attributed nearly 20 percent of Legionnaires’ disease cases in the United Kingdom not associated with hospitals or outbreaks to automobile windshield washer fluid.

It should be noted that the outlined study is the first to detect high levels of Legionella in automobiles or aerosolized by washer fluid spray, potentially due in part to the warm climate of Arizona providing a convenient environment for the survival of these heat-loving bacteria. While potential transmission of a deadly respiratory disease from a source as common as automobile windshield washing systems is significant, the study also points to the fact people can be exposed to pathogens – particularly those occurring naturally in the environment – in previously unknown and unusual ways.

David Schwake
Arizona State University
Tempe, AZ, United States
Phone: 602-819-4789