Fragrance and Lotion Use Diminishes Protective OH Radicals Indoors, Study Finds.

A recent study has found that using everyday personal care products like fragrance and body lotion significantly reduces levels of hydroxyl (OH) radicals near the human body, potentially altering the chemical makeup of indoor air. As people spend approximately 90% of their time indoors, understanding how such products interact with air chemistry is crucial, especially since the health effects of many resulting compounds remain largely unknown.

Indoor environments are saturated with chemical emissions originating from building materials, furniture, and daily human activities such as cooking and cleaning. Outdoor pollutants, particularly ozone (O₃), also infiltrate through ventilation and interact with indoor substances, forming a complex array of airborne compounds. When ozone encounters human skin, it triggers reactions that generate OH radicals—reactive molecules important in breaking down pollutants in the air.

In a groundbreaking study published in Science Advances, Jonathan Williams and his team from the Max Planck Institute for Chemistry examined how personal care routines affect this so-called "human oxidation field." This self-generated zone of chemical activity plays a vital role in shaping the air composition immediately surrounding a person.

“Since this oxidation field influences the chemical environment we inhale, it directly affects our chemical exposure and thus our health,” said Williams. The team collaborated with researchers from the University of California, Irvine, and Pennsylvania State University, employing advanced modeling techniques to simulate how human activities impact indoor chemistry.

Manabu Shiraiwa's team at UC Irvine developed a chemical model that mimics how ozone reacts with human skin and clothing to form semi-volatile organic compounds. Meanwhile, Donghyun Rim's group at Penn State applied a three-dimensional computational fluid dynamics model to map the spatial and temporal behavior of the oxidation field around individuals.

The study involved controlled experiments at the Technical University of Denmark in 2021, where four participants spent time in a specially designed climate-controlled chamber. Ozone was introduced into the chamber at safe yet realistic indoor levels, enabling researchers to observe how personal care products influenced OH levels.

Initial tests showed that applying body lotion reduced OH concentrations in the air surrounding the test subjects. When perfume was applied, the effect was similar. According to Williams, the primary component in perfume—ethanol—reacts with OH radicals without generating new ones. In the case of lotion, one explanation lies in phenoxyethanol, a common ingredient that similarly consumes OH without producing more. Additionally, the lotion physically blocks ozone from reaching skin compounds like squalene, further dampening OH production.

“The simultaneous use of perfume and lotion showed that perfumes have a more short-term effect on OH levels, while lotions cause a more prolonged reduction, aligning with the slower emission rates of their active compounds,” explained Nora Zannoni, the study’s lead author.

Despite the wide variety of formulations in commercial personal care products, researchers concluded that most lotions are likely to suppress the human oxidation field. This suppression results from both chemical reactions and the physical interference with skin-ozone interactions. Notably, preservatives like phenoxyethanol, commonly used for antimicrobial purposes, also play a role in depleting OH radicals.

These findings have important implications for indoor air quality. “Even well-tested furniture can emit chemicals that we transform through our own oxidation field when we interact with it. By applying products like lotion or perfume, we may be inadvertently muting this transformation process,” said Williams.

By combining real-time measurements with sophisticated simulations, the study provides new insight into how seemingly routine personal care choices can influence the air we breathe indoors—and ultimately, our health.

Source:https://phys.org/news/2025-05-fragrance-lotion-radicals-skin-affecting.html

This is non-financial/medical advice and made using AI so could be wrong.