A public health expert has raised concerns about a surprising source of bacterial infection—windshield wiper fluid. According to Dr Alex Sundermann, an epidemiologist and assistant professor at the University of Pittsburgh, certain types of wiper fluids can harbour Legionella bacteria, which can cause Legionnaires’ disease, a severe form of pneumonia.
Dr Sundermann revealed that when drivers activate their windshield wipers, the fluid can aerosolise, spreading fine particles of bacteria into the air. When inhaled, these bacteria can infect the lungs and lead to respiratory illness. In one study conducted on school buses, over 80 percent of wiper fluid tanks were found contaminated with Legionella bacteria, showing high concentrations capable of triggering infection.
The risk is not limited to buses—truck drivers and car owners could also be affected. In a reported case, two truck drivers developed Legionnaires’ disease after exposure to contaminated windshield wiper reservoirs. Tests confirmed the presence of Legionella in the wiper systems of their vehicles, suggesting a direct link between the fluid and the illness.
To prevent bacterial growth, Dr Sundermann recommends using wiper fluids that contain methanol, an ingredient that works both as an antifreeze and disinfectant. He explains that higher methanol levels can effectively kill Legionella bacteria. “All-season windshield wiper fluids usually contain enough methanol to prevent bacterial contamination,” he adds, warning against summer or methanol-free variants that could actually promote bacterial growth.
Drivers are advised to check product labels carefully and ensure their wiper fluids list “contains methanol.” This small precaution can significantly reduce the risk of inhaling harmful bacteria during routine driving.
Dr Sundermann concludes that infectious diseases can arise from common environmental sources—not just from exotic or unfamiliar origins. Everyday habits, like using windshield wipers, can expose people to hidden microbial threats if preventive steps aren’t taken.
