• Ivan Bristow

I can feel it coming in the air tonight....



A great lyric from a 1980’s hit with a memorable drum rift. You are probably wondering what this is blog is all about but recently I came across an article from the Journal of Investigative Dermatology (the highest impact factor rated journal in the field). The piece, which is due to be published shortly, examines the effects of air pollution on the skin and its normal function. So, often we think about poor air quality as a cause of lung and heart problems, but it would seem the skin is not "immune" to the effects from it too.

Air pollution exists as particles of differing sizes made up of solid and liquid components (including sulphates, hydrocarbons and benzene amongst other things) within our atmosphere. Particles may be graded by their size as being coarse (diameter <10um – known as PM 10), fine (diameter < 2.5um; PM 2.5) and ultrafine (diameter < 0.1um; PM 0.1).




Previous work has uncovered how particles on the skin can increase oxidative stress and promote inflammation leading to detectable skin damage. Moreover, exposure to this matter is known to exacerbate many dermatological diseases. A study group from the USA & Brazil undertook experiments on reconstructed human epidermis and exposed it to coarse grade particles [1]. The particle ingredients were standardised to reflect “normal” pollutants detectable in the urban atmosphere (such as hydrocarbons, aromatic chemicals and pesticides). The skin model was constructed from human keratinocytes.

The skin model was exposed to the coarse grade (PM 10) particulate matter for 48 hours with increasing dosages of the pollutants to observe its effects. The results demonstrated that the effects were clearly observable. The normal cell layer architecture of the epidermis showed disorganisation and loss of cell stratification with measurable cytotoxic cell death at the highest level of exposure (17.9µg / cm 2). Natural skin proteins essential for normal function such as filaggrin and involucrin were also significantly decreased. In addition, skin permeability was seen to increase with damage to the water channels in the epidermis. Levels of inflammation were also detected by an increased presence of the inflammatory cytokine IL-1 α.

This work, of course, is only based on a model in a laboratory but certainly does highlight how the skin may be just as vulnerable to air pollution as other organs. This work follows previous reviews of the subject and adds to the current knowledge. Exposure to these toxic air bourne agents have multiple effects on reducing the skin barrier function and structural proteins in the epidermis and promoting inflammation. Earlier work has shown that air pollution can also contribute to skin ageing [2]. The other aspect not to forget is those with pre-existing skin conditions. Atopic dermatitis, a common skin disorder is characterised by an impaired skin barrier. A review of the effects of pollution in these patients concluded that not only can it lead to exacerbation of symptoms but also lead to an increase in prevalence amongst the population [3]. This work suggests various strategies that may be helpful in this patient group which could reduce the effects of pollution including end-of-day skin washing to remove pollutants and emollient use to promote skin barrier repair. The use of creams containing vitamin C and E could be beneficial because of their known antioxidant properties but this needs further work.

References

1. Hieda, D.S., et al., Air particulate matter induces skin barrier dysfunction and water transport alteration on a reconstructed human epidermis model. Journal of Investigative Dermatology, 2020: Early view.

2. Schikowski, T. and A. Huls, Air Pollution and Skin Aging. Curr Environ Health Rep, 2020. 7(1): p. 58-64.

3. Hendricks, A.J., L.F. Eichenfield, and V.Y. Shi, The Impact of Airborne Pollution on Atopic Dermatitis—A Literature Review. British Journal of Dermatology, 2020. Early view.

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