We all have a sort of chemical force field around us. It’s not a metaphor and it’s not science fiction — it’s a swarm of reactive molecules swirling around our bodies. Scientists call this the human oxidation field. And for the first time, they’re discovering just how fragile it can be.

A new study published in Science Advances has revealed that personal care products (especially perfumes and body lotions) can significantly disrupt this oxidation field. The effects are not clear, but they could reduce our chemical defenses and transform the very air we breathe.

Back in 2022, researchers at the Max Planck Institute for Chemistry discovered that humans can generate high levels of hydroxyl radicals (OH) indoors. These radicals are potent oxidizers, often described as the atmosphere’s “detergents” because they react with and neutralize airborne pollutants.

We don’t fully understand what this oxidation field does, but it seems to form when ozone reacts with natural oils from sebum in our bodies. But what happens when we add chemicals to the mix — specifically, those found in lotions and perfumes?

That’s what Jonathan Williams and an international team of researchers set out to find. They conducted a series of chamber experiments. Volunteers entered a climate-controlled room either bare-skinned or after applying a commercial lotion or a popular fragrance. Ozone was then introduced, mimicking indoor air conditions when outdoor pollution seeps inside.

“Our team took a unique approach to simulate concentrations of chemical compounds near humans in the indoor environment,” said co-author Manabu Shiraiwa from the University of California Irvine. “We developed a state-of-the-art chemical model that can simulate reactions of ozone with human skin and clothing that can lead to the formation of semi-volatile organic compounds.”

“We applied a three-dimensional computational fluid dynamics model to simulate the evolution of the oxidation field around human occupants,” added co-author Donghyun Rim’s from the Pennsylvania State University. “This integrated modeling approach highlights the impact of personal care products on the human oxidation field.”

Perfumes tamper with our chemical defenses

The results painted a clear picture: both perfumes and body lotions have an effect. Fragrances rapidly elevate OH reactivity but have short-lived effects. Lotions, on the other hand, release compounds more slowly but influence the oxidation field for much longer.

“The application of a fragrance and a lotion together showed that fragrances impact the OH reactivity and concentration over shorter time periods, whereas lotions show more persistent effects, consistent with the rate of emissions of organic compounds from these personal care products,” sums up Nora Zannoni, first author of the study. 

Even natural-sounding ingredients aren’t off the hook. In a sensitivity test, the researchers looked at linalool, a terpene found in lavender essential oils. It also increased OH reactivity, though to a lesser extent.

But what does this effect actually do?

Scientists are just beginning to understand the implications. On one hand, suppressing the oxidation field could reduce the formation of harmful byproducts from skin-oil reactions. On the other, it might expose us more directly to other volatile organic compounds (VOCs) that the OH field would otherwise neutralize.

Importantly, this field isn’t only about airborne pollutants. It also affects particles on surfaces and dust. Hydroxyl radicals help break down chemical residues in our homes, and when this process is altered, it could change what ends up in our lungs and on our skin.

Indoor chemistry matters more than we think

When we talk about pollution and chemicals in the air, we usually think about the outdoors. But increasingly, science is showing that indoor chemistry is affecting our health in ways we previously overlooked.

We spend up to 90% of our time indoors, and that means we’re constantly inhaling and interacting with indoor pollutants. Some of these come from furniture and building materials. Others are created in real-time by us. There’s more stuff indoors and less space for chemicals to disperse. That’s why concentrations of many chemicals (including CO₂) are significantly higher indoors than outdoors.

This is also the case for this study. Perfumes and lotions are typically applied in homes, offices, or other indoor settings. They linger more inside than outside. The human oxidation field is more prominent and stable indoors, and any changes to it would also be more impactful indoors.

Journal Reference: Nora Zannoni et al, Personal care products disrupt the human oxidation field, Science Advances (2025). DOI: 10.1126/sciadv.ads7908