“Spray drops” hang in the air after washing the toilet


By Cara Murez

HealthDay Reporter

THURSDAY, APRIL 22, 2021 (HealthDay News) – If you are in a public restroom, you may not want to spend too much time, because there are many airborne pathogens as well.

Researchers from the Florida Atlantic University College of Computer Engineering and Science conducted washing tests in a public restroom with a toilet and urinal.

“After about three hours of testing involving more than 100 flushes, we found a substantial increase in the aerosol levels measured … with the total number of drops generated in each wash test going up to the tens of thousands, ”said Siddhartha, co-author of the study. Verma. He is an assistant professor of mechanical and ocean engineering at the university.

The pathogens that can cause Ebola, norovirus, and even COVID-19 can be found in stagnant water, as well as in urine, feces, and vomiting. According to the research team, washing can generate large amounts of airborne germs, depending on the washing power, toilet design and water pressure.


For the study, the researchers placed a particle counter at various heights of the toilet and urinal to capture the size and number of drops generated by washing. They did the same with a covered toilet. (Few public restrooms in the United States have lids and urinals are not covered.)

The findings detected drops at heights of up to 5 feet for 20 seconds or more after starting the wash.

Investigators detected fewer drops when the lid was closed before washing, but the number was no less. This suggests that spray drops escaped through small gaps between the deck and the seat.

Verma noted that both the toilet and urinal generated large amounts of droplets of less than 3 micrometers, presenting a significant risk of transmission if they contained infectious microorganisms.

“Because of their small size, these drops can remain suspended for a long time,” Verma explained in a university press release.

The researchers reported a 69.5% increase in measured levels of particles between 0.3 and 0.5 micrometers in size; a 209% increase for particles from 0.5 to 1 micrometer; and a 50% increase for particles between 1 and 3 micrometers.


According to the study’s co-author, Masoud Jahandar Lashaki, “the significant accumulation of aerosolized droplets generated by flush over time suggests that the ventilation system was not effective in removing them from the enclosed space even though there is no there was a noticeable lack of airflow inside the sink. ”Lashaki is an assistant professor of civil, environmental and geomatics engineering.

“In the long run, these aerosols could increase with currents created by the ventilation system or by people moving in the toilet,” he explained.

Even larger aerosols can add risk, the study authors noted.

Co-author Manhar Dhanak, president of ocean and mechanical engineering, noted that the study suggests that “incorporating adequate ventilation in the design and operation of public spaces would help prevent the buildup of aerosols in areas with high occupancy, such as public toilets “.

The sink was thoroughly cleaned and closed 24 hours before the experiments were performed and the ventilation system was functioning normally.

The report was recently published in the journal Fluid physics.

Stella Batalama is the school’s dean of engineering and computer science. He concluded that “aerosolized droplets play a central role in the transmission of various infectious diseases, including COVID-19, and this latest research from our team of scientists provides additional evidence to support the risk of infection transmission in confined spaces. and poorly ventilated “.


More information

U.S. Centers for Disease Control and Prevention have more to consider COVID-19[feminine[feminine.

SOURCE: Florida Atlantic University, press release, April 20, 2021

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