Exploring Indoor Nanoparticle Formation

Last month, the American Chemical Society (ACS) Fall 2026 Meeting took place at the McCormick Place Convention Center, in Chicago, Illinois, from August 23–27^th.¹ At the meeting, there were several talks dedicated to environmental analysis and specifically on analyzing air quality. One of those talks, titled “Indoor Atmospheric Nanoparticle Formation from Scented Cleaning Products,” was given by Brandon E. Boor, who is the Dr. Margery E. Hoffman Associate Professor in Purdue University's Lyles School of Civil and Construction Engineering.^1,2

In a retrospective of the ACS Fall 2026 Meeting, Boor sat down with Spectroscopy to recap his talk and highlight his group’s research. In this article, we preview our upcoming interview with Boor and recap his talk at the ACS Fall 2026 Meeting.

What was the main premise of the talk?

Boor’s research was anchored around the premise that surface cleaning and disinfection with scented products can trigger nanoparticle formation events indoors at rates and concentrations that exceed those from outdoor combustion sources such as vehicle traffic.² At the ACS Fall 2026 Meeting, Boor presented findings from a few of the studies he and his team conducted, showing that terpenes and terpenoids released by conventional and botanical cleaning products react with indoor ozone to rapidly nucleate and grow airborne nanoparticles.²

What was the main goal of Boor’s research?

The main research objective was to gain a better understanding how routine cleaning affects indoor air chemistry at the smallest particle scales. Although scented volatile chemical products have long been recognized as major sources of reactive organic emissions, their specific role in driving nanoparticle formation had not been well characterized until now.²

Boor’s team used real-time, high-resolution instrumentation capable of measuring particles down to the nanocluster aerosol regime (1 to 3 nanometers) to monitor controlled residential and office environments during cleaning and disinfection activities.² The application of scented cleaning agents produced terpene and terpenoid mixing ratios of 10 to 1,000 parts per billion (ppb).² These are levels the researchers noted often exceeded those measured in outdoor forested environments, where such compounds are naturally abundant.

The compounds reacted with the ozone already present indoors. Because of this, nucleation events are triggered, with rates approximately 100,000 particles per cubic centimeter per second.² Condensational growth rates reached up to 300 nanometers per hour, and transient nanoparticle concentrations climbed to between 100,000 and 100 million particles per cubic centimeter.²

Why do these growth rates matter?

The growth rates matter because they determine whether particles survive long enough, and reach a size, that allows efficient deposition throughout the human respiratory tract.² Boor explained during his presentation that the dose rates were comparable to or greater than those associated with primary combustion sources like traffic emissions.²

Boor's team found that both conventional cleaning products and botanical, or "natural," disinfectants generated similarly complex exposure scenarios, involving mixtures of reactive gases and secondary organic aerosol.²

What will the upcoming interview with Boor cover?

Boor's presentation, "Indoor Atmospheric Nanoparticle Formation from Scented Cleaning Products," was delivered as part of the ACS Fall 2026 meeting's technical program. Our full interview with Boor will be released next week in three parts. Part 1 of our conversation with Boor will focus on the instrumentation and methodology behind measuring nanoparticle size distributions at the nanocluster scale (1–3 nm), outlining the technical challenges of acquiring reliable, real-time data at these dimensions. Part 2 of our interview will delve into how his team controls experimental variables during cleaning experiments in order to obtain interpretable data. And finally, Part 3 will explore the respiratory deposition model Boor’s team used to analyze indoor particle exposure.

References

1. Wetzel, W.; Spectroscopy Staff. Why Spectroscopists Should Attend the ACS Fall 2026 Conference. Spectroscopy Online, 2026. https://www.spectroscopyonline.com/view/why-spectroscopists-should-attend-the-acs-fall-2026-conference (accessed September 9, 2026).
2. Boor, B. E. Indoor Atmospheric Nanoparticle Formation from Scented Cleaning Products. Presented at the American Chemical Society Fall 2026 Meeting, in Chicago, Illinois. Available at: https://acs.digitellinc.com/live/37/session/591663