September 1, 2026
Health & Air Quality | September 1, 2026 | 2 min read
A team of researchers presented findings at the American Chemical Society's fall 2026 meeting on August 27, showing that scented cleaning products can react with ordinary indoor air to generate large quantities of nanoparticles, some small enough to reach deep into the lungs within minutes of use. The study was led by Brandon Boor, a civil and construction engineering researcher at Purdue University.
Most coverage of the study has focused on the chemistry: what terpenes are, how they react with ozone, and how quickly that reaction happens. The practical question for most households is simpler. If routine cleaning is adding measurable amounts of fine particles to the air, what does that mean for the filtration already running in your home? Here is what the study found and what it changes about indoor air.
Boor's team tested common scented cleaning products inside a controlled model home. When fragrance compounds called terpenes, found in citrus- and pine-scented cleaners, evaporate into the air, they react with ozone that's already present indoors. That reaction doesn't just create a smell. It creates particles.
The numbers are notable. A single cleaning session produced billions to trillions of nanoparticles, most measuring just 1 to 30 nanometers wide, a size so small that standard home air quality monitors typically miss them entirely. Indoor particle concentrations reached as high as 100 million particles per cubic centimeter, with terpene levels spiking 10 to 1,000 parts per billion, tens to hundreds of times higher than what you'd find walking through a forest.
According to Boor's team, in some cases it's worse. "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," the researchers noted. The formation also happens fast. By the time you've finished wiping down a counter, you may have already inhaled a meaningful share of those particles.
It can. The study found that running germicidal UV-C lamps at the same time as scented cleaning products pushed indoor ozone levels up to 20 to 40 parts per billion, comparable to outdoor readings during the experiment, which fed even more particle formation. Combining the two habits in the same space compounds the problem rather than canceling it out.
Part of the issue is regulatory. Under current U.S. labeling rules, manufacturers can list "fragrance" as a single ingredient even when it represents a blend of dozens or hundreds of individual chemicals. The EPA has separately noted that concentrations of volatile organic compounds, the broader chemical category fragrances fall into, are routinely up to 10 times higher indoors than outdoors, and there are currently no federally enforceable indoor air quality standards for VOCs in homes.
Researchers point to a few practical habits: reach for unscented or low-fragrance cleaning products when possible, run exhaust fans or crack a window while cleaning, and avoid pairing scented products with ozone-generating devices like UV-C lamps. Ventilation does a lot of the work here, since ozone and terpenes both need to be present at the same time, in the same space, for the reaction to happen.
Where filtration fits in
None of those habits do anything about particles already moving through your ducts between cleanings, and that's a job ventilation can't finish on its own. That's what your HVAC filter is there for.
Sources: ACS Pressroom, Phys.org, Respiratory Therapy, News-Medical, Newswise, U.S. EPA
