Scientists Raise Alarm Over New Invisible Indoor Air Pollution

Photo of a woman using carpet cleaner. Popular cleaning products often contain nano-sized specks of metals, which can be sent flying in the air when we walk near them.

Engineered specks of metal in consumer cleaning products might be contributing to a new form of indoor air pollution, scientists warn. Children may be particularly at risk even after the spray has settled, the results of a new study show.

Nanomaterials, often made from silver, copper and zinc, are widely used in a range of popular household products, including cleaners, disinfectants and hairsprays. These particles behave very differently compared to the metals when they are present “in bulk”—for example, they may be more magnetic, better at conducting heat and electricity, or more chemically reactive. The problem is that they may also be more toxic than their bulky counterparts, raising questions about their impact on human health.

“There is very limited knowledge of the potential for exposure to nanoparticles from consumer products and resulting health effects,” Gediminas Mainelis, a professor in the Department of Environmental Science at Rutgers School of Environmental and Biological Sciences who has been studying these substances for over a decade, said in a statement.

Many of us are aware of the potential risks associated with breathing in cleaning products as we spray them, but a new study, published in the journal Science of the Total Environment, has shown that these nanomaterials can become resuspended in the air long after they have settled.

“If an adult is walking in a room, and steps on some of these deposited particles, we found that the particles will be re-suspended in the air and rise as high as that person’s breathing zone,” Mainelis, who led the study, said. “A child playing on the floor inhales even more because the concentrations of particles are greater closer to the ground.”

To achieve these results, the researchers constructed an enclosed, air-controlled chamber with both carpeting and vinyl flooring. The researchers sprayed seven products containing these metal nanoparticles into the air and allowed them to settle. They then entered the chamber wearing protective suits and respirators and measured how many of the nanoparticles were re-released back into the air.

They also used small robots to simulate the actions of a child.

The seven products they tested included “a silver (Ag)-based shoe deodorizer, an Ag-based surface cleaner, an Ag-based immune system support hydrosol, two zinc (Zn)-based skin protectants, a Zn-based immune system defense booster, and a copper-based skin toner.”

Not only did their results show the re-suspension of these particles into a “person’s breathing zone,” but they also found that carpet flooring released a significantly high concentration of these particles compared to vinyl.

“Overall, this work could help us understand the resulting exposures and support future studies on human exposure reduction,” Mainelis said. “We can use this knowledge to minimize our exposures, in this case to various nanomaterials.”

At this point, it is unclear how serious a health risk these nanoscale metals pose to humans, but Mainelis said that research like this was still important to spread awareness about the particulate matter present in their own homes.

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