This “tiny house lab,” which sits outside Purdue’s Delon and Elizabeth Hampton Hall of Civil Engineering, allows researchers to study indoor air quality more comprehensively than has been possible in other settings. Credit: Purdue University photo/Kelsey Lefever
Fragrance compounds in common cleaning products react with ozone in the air to form billions of invisible nanoparticles, creating a respiratory dose that can rival or exceed exposure from standing near a busy road, according to new research.
Terpenes—the fragrance compounds responsible for scents like pine, lemon, thyme and lavender—are already known to react with ozone in outdoor air, forming airborne nanoparticles that can eventually grow large enough to seed clouds. In forests, where terpenes like pinene occur naturally at low concentrations, that particle formation happens slowly. But scented cleaning products release terpenes at concentrations 10s to 100s of times higher than what's found outdoors.
To study what happens during routine cleaning, researchers at Purdue tested scented conventional products and botanical disinfectants in a model house on campus equipped with a working kitchen, wood flooring and a bathroom. They found that mopping, spraying countertops and wiping surfaces with scented products formed billions or trillions of nanoparticles, most between 1 and 30 nanometers wide—a size range often missed by home air quality monitors. Because these particles are small enough to travel deep into the lungs, they can contribute to respiratory irritation and inflammation, or potentially enter the bloodstream. The particles formed within minutes of starting to clean.
The research team also found that combining scented cleaning products with germicidal far-UV lamps, which generate ozone as a byproduct, intensified particle formation even further, raising ozone levels in the tiny house to between 20 and 40 parts per billion.
“We showed that indoor ozone reactions with fragrances from cleaning produce nanoparticles that carry a respiratory dose comparable to, or greater than, what you would experience from standing outside along a busy road,” said Brandon Boor, assistant professor of civil and construction engineering at Purdue University. “The particles are different in terms of their composition, but the total dose can be higher. You're not seeing smoke, dust, or haze in the air. Instead, you think the air smells great so it must be clean.”
Boor said the goal is to help people clean more safely without giving up the practice altogether. The project and results were presented at the fall meeting of the American Chemical Society,
Data from American Chemical Society