Given that people spend up to 90% of their time indoors, ensuring good indoor air quality is crucial for minimizing exposure to pollutants.

The study highlights significant implications for indoor air chemistry and human health, as these products alter the chemical composition of the 'human oxidation field,' which is crucial for protecting individuals from ozone exposure.

Although the initial reaction of the oxidation field can prevent ozone inhalation, it leads to secondary reactions that release new chemicals into the air, the effects of which are still being studied.

Researchers found that fragrances and lotions change how skin oils react with ozone, leading to the formation of highly reactive hydroxyl (OH) radicals that create a protective barrier around the body.

With the global market for personal care products estimated at $646.2 billion in late 2024, the findings underscore the importance of understanding their impact on air quality, especially in densely populated areas.

While fragrances initially had a stronger impact on OH reactivity, they were less persistent than lotions, which maintained their effects longer due to slower emissions of organic compounds.

An international research team, including scientists from Penn State, published a study on May 28, 2025, in the journal 'Science Advances' that reveals how personal care products like perfumes and lotions disrupt the body's natural defenses against indoor air pollutants.

Lead author Nora Zannoni noted that the combination of lotion and fragrance shows differing impacts on OH reactivity over time, with lotions having longer-lasting effects.

Ethanol in fragrances reduces the strength of the oxidation field by acting as a hydroxyl radical sink, further complicating the body's defense mechanisms.

In controlled experiments, volunteers were tested for oxidative protection before and after applying personal care products, revealing significant disruption of their natural oxidation field.

The research utilized innovative multiphase chemical kinetic modeling and computational fluid dynamics to visualize chemical concentrations near humans indoors.

The oxidation field is formed when oils and fats on the skin react with ozone, a significant indoor oxidant, as detailed in the team's previous research.