A spray of perfume or a swipe of lotion could mess with highly reactive chemicals clouding your body, according to new research, leading to unknown health effects.
This chemical shield is known as the human oxidation field, and scientists think it reacts quickly with molecules surrounding us, neutralizing some volatile compounds.
A new study has found, however, that when perfume or lotion is applied to the skin, it can transform the air chemistry in its immediate vicinity, potentially sending toxic chemical byproducts wafting up our noses or sinking into our skin.
“Given that the human oxidation field influences the chemical composition of air in the breathing zone and close to the skin, it affects our intake of chemicals, which, in turn, affects human health,” says Max Planck Institute atmospheric scientist Nora Zannoni and colleagues.
Much is still unknown about the human oxidation field and how it impacts our health. It was only discovered in 2022, when a team led by several of the same scientists found that oil from the skin reacts with ozone pollutants in the air to form a field of hydroxyl (OH) radicals around the human body.
OH radicals are sometimes described as an atmospheric ‘detergent’, because they can react with and neutralize a wide range of airborne pollutants.
At the same time, it’s possible that some of these chemical reactions may produce potentially dangerous byproducts right next to our skin and airways.
Figuring out how the human oxidation field interacts with chemicals in our indoor and outdoor environments is a new field in health research.
In the current study, four young adults sat in a temperature-controlled indoor environment, and scientists measured the chemicals around their body and in the air when they had and had not applied personal care products.
When some participants had applied lotion just prior to entering, researchers noticed that two chemicals – phenoxyethanol and ethanol – drifted upward from the skin on ‘thermal plumes’, dispersing into the ambient air with body heat.
The concentrations of these lotion chemicals around each participant continued to steadily rise, even a whole 10 minutes after their application. Concentrations near the nose, for instance, were 2.8 times higher than those in the ambient air.
Then, researchers released ozone from an inlet in the floor below participants. Ozone is formed when sunlight interacts with volatile organic compounds, and while it exists at higher concentrations outdoors, it can seep into buildings, reacting with our skin oil to create a human oxidation field.
The team found that body lotion reacted with the human oxidation field from head to toe, hampering ozone’s generation of a key OH precursor, and reducing its concentration around participants by 34 percent.
A similar result occurred when participants applied a fragrance to the backs of their hands before entering the controlled environment.
Both ethanol and monoterpenes rose around the participants, with levels 10 times higher above the participants’ heads than in the surrounding ambient air.
These chemicals also reacted with the OH radicals surrounding the human body, reducing their concentrations in the oxidation field.
“This study has determined that the human oxidation field generated by people exposed to ozone indoors is substantially disrupted when personal care products are worn,” write the authors.
The team did not investigate the health effects, just the chemical changes surrounding the human body, but they are concerned by the volatile reactions happening around us.
“We need to rethink indoor chemistry in occupied spaces because the oxidation field we create will transform many of the chemicals in our immediate vicinity,” said atmospheric chemist Jonathan Williams, project leader of the 2022 study that discovered the human oxidation field.
“OH can oxidize many more species than ozone, creating a multitude of products directly in our breathing zone with as yet unknown health impacts.”
The study was published in Science Advances.
