The Exposome || Pollution and Skin
Earlier this month, we delved into the two processes behind skin ageing, the intrinsic and extrinsic ageing factors. To understand the background to this week’s article, have a little read here. In this week’s article, we will focus on another extrinsic factor that can alter the functioning and integrity of our skin as we age.
While we addressed this before, it always bears repeating: the biggest culprit in exposome, or extrinsic skin ageing, is the damage caused by UV rays. See the following article on how to best protect your skin with the right sunscreen for you.
Pollution and the Skin
A lesser discussed extrinsic skin ageing factor is air pollution. The WHO has determined air pollution to be “a major environmental risk to health”.(1) Ambient Air Pollution (AAP) is a term used to refer to outdoor environmental pollution and comprises the following key pollutants; particulate matter (PM), Ozone (O3), Nitrogen Dioxide (NO2) and Sulfur Dioxide (SO2). The link between AAP and cardiopulmonary disease and certain cancers has led researchers to consider the possible deleterious effects on other organs. The contribution of AAP to the process of skin ageing is beginning to be revealed. As our skin is the organ most exposed to the elements, it is logical that it could be vulnerable to the negative impacts of pollution. Certainly, in the instance of pre-existing skin diseases, AAP can exacerbate many conditions – as seen in a longitudinal study examining AAP and atopic dermatitis (eczema).
The Science
The landmark SALIA study demonstrates an association between airborne particulate matter and signs of skin ageing. It was a cross-sectional, epidemiological study conducted on 400 Caucasian female participants, evenly distributed between rural and urban regions of Germany.(2) Following SALIA, there are signs that a link between facial solar lentigines (sun spots) and exposure to higher levels of traffic emissions exists. Other possible associations found included more prominent nasolabial folds (nose to mouth lines) with exposure to soot and more pigment spots associated with closer proximity to a busy road.
Follow-up studies have indicated similar results. In 2016, a further epidemiological study was carried out, focusing on the association between chronic exposure to NO2 and sun spot formation and included findings from an independent cohort study of Asian females. This study further supports the possible association between pollution and solar lentigines.(3) An additional analyses of the data, implicated the potential interplay of sun and AAP on the formation of SL.
The role pollution has to play in extrinsic ageing is believed to relate to the oxidative stress caused by AAP. Additionally, some aspects of AAP have been shown to have the ability to activate melanocytes and produce melanin in the absence of sunlight. It has been suggested that this may explain the prevalence of sun spots as manifestations of premature ageing in Asian populations who typically avoid sun exposure.
One component of AAP that is slightly better understood is O3, a distinct entity from the ozone layer. O3 is a major component of smog and results from a chemical reaction between O2 and UVR, and is a highly reactive molecule that is readily oxidised in the stratum corneum due to its rich polyunsaturated fatty acids (PUFA) and lipids content. This lipid peroxidation process results in reactive oxygen species formation and can trigger a series of free radical reactions. Furthermore, O3 has been shown to deplete cutaneous vitamin C and E concentrations, induce pro-inflammatory markers, and result in heat shock proteins. The culmination of these processes results in the disruption to the integrity of the skin leading to irritation, loss of radiance and reduced hydration.
Maintaining Skin Health
The importance of identifying these mechanistic intricacies lies in the possibility of identifying potential interventions to counteract them. As in the case of O3 induced damage, antioxidant supplementation/ a diet rich in antioxidants can mitigate the effects by reducing the formation of oxidation products. Short of moving to the countryside, it is very difficult to avoid daily encounters with air pollution, particularly if you live in a busy city. At Le Formulaire we have a few golden rules to help our community combat AAP.
We advise everyone to incorporate a powerful antioxidant into their daytime routine to minimise this damage.
It is also vital to wear a sunscreen daily as the effects of pollution appear to be accelerated in the presence of UV rays.
After a day in the city (or anywhere really!) is essential to remove the particulate matter from your delicate visage with a double cleanse.
Gentle exfoliation can help to remove the cells of the stratum corneum that have been battling pollution all day. Once or twice a week is helpful.
We hope you found this useful. Stay tuned for the next in our exposome series as we reveal the next biggest skin ageing culprit.
WHO. Air Pollution 2018 [Fact Sheet]. Available from: https://www.who.int/en/news-room/fact-sheets/detail/ambient-(outdoor)-air-quality-and-health.
Vierkötter A, Schikowski T, Ranft U, Sugiri D, Matsui M, Krämer U, et al. Airborne particle exposure and extrinsic skin aging. J Invest Dermatol. 2010;130(12):2719-26.
Hüls A, Vierkötter A, Gao W, Krämer U, Yang Y, Ding A, et al. Traffic-Related Air Pollution Contributes to Development of Facial Lentigines: Further Epidemiological Evidence from Caucasians and Asians. J Invest Dermatol. 2016;136(5):1053-6.
