Cleaning Products May Push Indoor Air Pollution to Traffic-Like Levels, Purdue Researcher Says

A presentation at the American Chemical Society's (ACS) fall symposium says everyday household cleaning and disinfecting products may push indoor air pollution to levels comparable with outdoor traffic pollution. Purdue University engineer Brendan Boor, who led a team of students studying the chemistry of cleaning agents, told the meeting that indoor cleaning and disinfection products are key drivers of nanoparticle formation – tiny airborne particles small enough to travel deep into the lungs.

The culprits are terpenes – the fragrance compounds behind cleaning products' lemon, pine, thyme or lavender scent. Plants make terpenes to ward off pests, and the compounds are generally considered safe in small ingested amounts. Boor's team found that spraying and wiping a surface can push indoor terpene levels higher than levels found in a forest. When terpenes react with ozone – a three-atom oxygen molecule produced by photocopiers, UV lamps and HEPA air purifiers – they condense into nanoparticles.

To measure this, the researchers took high-resolution readings of terpenes and other airborne compounds inside a purpose-built tiny house at Purdue, comparing results with outdoor air. "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," Boor said.

Boor said the nanoparticles can settle deep in the lungs and pass into the bloodstream, adding: "by the time you finish cleaning up an indoor space, you've already formed a lot of nanoparticles and inhaled them." The particles can irritate airways and promote inflammation, though the researchers stressed nobody is claiming this indoor terpene haze is as risky as standing at a busy city intersection.

Boor's advice is to open a few windows while cleaning, choose low-fragrance cleaning products, and get used to a home's natural scent. The findings were presented at the ACS symposium session "Healthy Indoor Spaces: Bridging the Microbiome and Chemistry."