U of S research shows hydrogen peroxide-based cleaners pollute indoor air

Cleaning with hydrogen peroxide-based disinfectants may give you more than dish pan hands.

New research led by the University of Saskatchewan shows it has the potential to be detrimental to the air quality in your house and to your health.

The research team found that mopping a floor with a commercially available hydrogen peroxide-based disinfectant raised the level of airborne hydrogen peroxide to more than 600 parts per billion — about 60 per cent of the maximum level permitted for exposure over eight hours and 600 times the level naturally occurring in the air,

"Just breathing in the hydrogen peroxide probably won't hurt our health," said University of Saskatchewan chemistry researcher Tara Kahan, senior author of the study and Canada research chair in environmental analytical chemistry.

"But there's enough hydrogen peroxide in the air after these cleaning events that it could react, undergo chemical reactions with other things that are in the air, which might then make the air quality not so good."

The results of the study were just published in the journal Environmental Science & Technology. 

According to the U.S. Centres for Disease Control, too much exposure to hydrogen peroxide could lead to respiratory problems like asthma or skin and eye irritation.

The experiment was done in 2018, before COVID-19, but Kahan said the results are especially relevant now that people are cleaning more often.

"At the time we just wanted to know what was happening when we were washing floors and counters and stuff, how that might be affecting air quality," she said. "Now people are doing an awful lot of washing surfaces." 

The project involved research groups from the U of S and York University in Ontario, and researchers at University of York in England and Syracuse University in the U.S.

The experiment

The experiments were done in an "atmospheric" at Syracuse University.

"That's a fancy way of saying it's a big box with air inside of it where we can study chemistry that's relevant to the atmosphere," Kahan said.

They were able to mimic the inside of a house, or at least one room. There were windows, doors, vinyl flooring, drywall and even huge fluorescent lighting to simulate the sun.

"This sort of fake room that's inside a lab lets us control things like temperature and humidity and also what gases are present."

Kahan and her team spent a couple of weeks spraying the vinyl floor with 0.88 per cent hydrogen peroxide disinfectant and wiping it dry with paper towel either immediately or after letting it soak in for an hour. The team then tested the air at human head height.   

She said it wasn't surprising the results showed hydrogen peroxide in the air.

"But this had never been done before and we had no idea how much hydrogen peroxide would get into the air," she said.

Normally the levels of hydrogen peroxide are at such low levels that instruments can't detect it.

"When we cleaned it, we saw that the levels went up by a factor of 100 or 1,000 to quite high levels that are very easy to measure."

Those levels were at the top end of what is recommended as a long-term exposure limit.

Conclusions

Kahan said the risk is more pronounced for people who are janitors or housecleaners.

"My takeaway from this is not that hydrogen peroxide is awful, but just that people should recognize that when they do things like clean surfaces, they are changing what's in the air and we can do things to mitigate any risks that are caused by this," Kahan said.

That includes:

• Using soap and water [which can kill the virus that causes COVID-19] instead of a disinfectant when possible.

• Ventilating the house by opening a window or turning on the range hood or central air systems.

"I don't want to say that cleaning with hydrogen peroxide is necessarily bad or that what we saw was really worrying. We need more information," said Kahan, who has previously studied the effects of gas stoves in houses.

Kahan said she will still clean with hydrogen peroxide if she thinks she needs to, because it is less harmful than bleach.

She said they are now in the process of taking measurements in houses and apartments. 

One problem researchers had over the summer was getting cleaning products.

"Everybody was buying them up. We couldn't even buy hydrogen peroxide," Kahan said.

"But once we did get our hands on some over the summer, we've done some measurements in a house looking at things like what happens when you open a window, when you clean larger areas versus smaller areas of the floor, that sort of thing. And that data is being analyzed right now."

The research funded by the Canada Research Chairs program and the Alfred P. Sloan Foundation,