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Practical Dermatology® recently sat down with Mark Birch-Machin, PhD, a professor of molecular dermatology at New Castle University, to talk about the effects that air pollution can have on skin. Dr. Birch-Machin also talks about a recent study his team published in FASEB BioAdvances looking at the effects of air pollution on human skin equivalents, as well as what can be done to reverse damage caused by ozone. Read partial transcript of the interview below.

Describe your study and its findings.

The title of the study is “Biological effects of air pollution on the function of human skin equivalents,” that was published in FASEB Bioadvances back in November 2023. We’re particularly happy with the publication because it actually made, one of the figures made the front cover. What the study did was to look at the pollution effects on 3D skin equivalents (living skin equivalents, full thickness skin, both the epidermis and the dermis). What we did was to expose these 3D skin equivalents to ozone on its own and to particulate matter on its own, but then a combinational aspect as well to look to see if there was any synergy that was going on.

We know as individuals walking around in 21st century that we were very rarely exposed to just one stressor, either ozone or particulate matter. That’s why we then mimicked that by combining the two and to see what happened. That was the study. Its findings really relate to the synergistic effects of the ozone and the particulate matter together. Ozone in particular had a matrix-degrading phenotype on the skin, but when it was combined with particulate matter, these effects were enhanced. And so really the surprise finding from our study was the fact that these two pollutants actually worked together to enhance damage to full thickness skin.

What surprised you about the study results?

It has been shown that there is synergistic induction of proinflammatory markers in the skin’s response to various stressors, including UV ozone, smoke temperature, and humidity. We know the fact that environmental exposure induces pro-inflammatory markers. However, in this study what we did was to take it further and look at combinations of some of these external stressors. We took ozone and particulate matter and asked the questions: what happens separately in terms of anti-aging markers or markers of matrix degradation in skin? What happens when you mix the two? What happens when you choose ozone? And what happens when you combine the two?

What was surprising is the fact it was this combinational approach—this synergistic effect of ozone and particulate matter—that was the interesting feature of this study (which is why it was highlighted on the front cover of FASEB). What we noticed was the fact that when you expose the skin to ozone on its own, it induces a kind of matrix-degrading phenotype. It actually decreased the amount of collagen content in the skin, which is a bad thing, but also increased matrix metalloproteinase. […] Ozone has two effects. One is that it decreases the collagen, and two, is that it increases an enzyme which degrades the matrix of the skin. Obviously, that’s not good either. That’s ozone. But when you throw in particulate matter, it enhances these effects a bit more. You’ve got this profound effect of ozone in its own, but when you add particulate matter, it seems to increase [this effect] more, whereas when you look at particulate matter on its own, that effect is not seen. There’s obviously a synergistic effect that is going on. That was the surprising thing from that point of view.

Source: Reynolds R, Christensen P, Li W, et al. Biological effects of air pollution on the function of human skin equivalents. FASEB BioAdvances. 2023;5(11):470-483.

Disclosure: The study referenced in the interview was supported by Kenvue and Croda. Dr. Birch-Machin was an investigator and author on the study, and has received research funding from Kenvue and Croda.