Skin diseases, pollution increase the risks of atopic dermatitis

When reflecting on air pollution and the effects of climate change, we hardly think about the effects they can have on the skin. Yet even the cloak that covers our body can be affected by what happens. As well as the earth. Today it is more than a degree warmer than what was recorded at the end of the 19th century. It is therefore not enough to think about the high temperatures we perceive. It is necessary to think that that of perceived thermal values it is only one aspect of a more complex problem, which must take into account all the connections that intersect in the relationship between the environment and human health, in a “One Health” logic. So, too dermatology he questions. And she does it on the occasion of the SIDeMaST congress, the Italian Society of Dermatology and Sexually Transmitted Diseases.

What relationships exist?

To reduce the risk of development and exacerbation of skin pathologiesespecially of Atopic dermatitis, we need environmental policy strategies that limit the use of fossil fuels, promote sustainable land management practices by reducing the amount of air pollution and include the installation of air filtering devices in indoor environments. Numerous studies have in fact demonstrated not only the connection between climate changes and increase in atopic dermatitis, but also between environmental pollution and an increase in pathology. Furthermore, the growing trend in air pollution, mainly due to the increase in motor vehicles and the use of coal for the production of electricity, impacts human health from pre-natal age. In fact, the exposure of future mothers to pollutants favors the risks of developing atopic dermatitis within the first six months of life of the newborn. Pollution resulting from forest fires also has its repercussions in terms of increased cases of atopic dermatitis in adults and children.

What is atopic dermatitis and why does pollution affect it

Atopic dermatitis is a chronic inflammatory skin disease characterized by a skin barrier defect and an altered immune response to irritants and allergenic substances. It can arise at any stage of life and is characterized by the presence of eczema with intense itching and significant negative impact on patients' quality of life.
It is constantly increasing in terms of incidence and prevalence, above all in industrialized countriesthe. In Europe and the United States, recent data suggests that it affects approximately 20% of children and 7-14% of adults, with substantial variations between different countries.
“It is known – explains Luca Stingeni, President of the Congress, Professor of Dermatology of the University of Perugia and Director of the Dermatology Clinic and of the Department of General and Specialist Medicine of the Perugia Hospital – that climatic variables how temperature, air humidity, pollen load and UV exposure influence the signs and symptoms of atopic dermatitis. But more recently, environmental pollution it has been reported as a factor in inducing and/or aggravating atopic pathology through multiple biological mechanisms. These include the formation of oxygen free radicals (ROS), oxidative stress, compromised skin barrier and an inflammatory response.”

How the epidermis changes

The skin represents the largest organ of the human body and acts as a barrier between the organism and the external environment. Therefore, constant contact with the environment and air pollutants can directly damage the skin's barrier function and alter homeostasis, that is, the process that tends to keep the internal conditions of the organism stable. This alteration contributes to the development and exacerbation of skin diseases, including atopic dermatitis. In particular, the skin of those affected is more sensitive when exposed to nitrogen oxide, ozone and polycyclic aromatic hydrocarbons (IPA).
“The alteration of the function of the epidermal barrier – explains the expert – is measured by the Dermatologist with the TEWL (Trans Epidermal Water Loss) method, i.e. the study of water loss through the epidermis. Already in 1998, a study conducted in Munich demonstrated that if the skin of subjects suffering from atopic dermatitis is exposed to nitrogen dioxide present in a polluted environment, TEWL increases as an indicator of compromise of the skin barrier”.
More recently (2018), some Chinese scholars have demonstrated that the alteration of the skin barrier is capable of generating free radicals and structural alterations of the cell membranes of the epidermis cells. It has also been proven that its function is compromised byexposure to particulate matter.

What happens to children

To evaluate the effects of air pollution on atopic dermatitis, numerous studies have been conducted in Europe which, although not homogeneous in terms of pollutants examined, source of pollution and concentration of polluting substances, have suggested a higher risk of developing atopic dermatitis and exacerbation of the symptoms of the disease when there is greater exposure to air pollutants.
“For example – continues Stingeni – newborns, who physiologically present a immature skin barrier, they may be particularly vulnerable to developing atopic dermatitis when living in urban areas. In a German study conducted in 2009 it was shown that proximity to major roads and greater exposure to polluted air (in particular, PM2.5 particulate matter) during early childhood are associated with a higher prevalence of atopic dermatitis. These results are supported by more recent studies conducted in South America and Korea in pediatric patients, which demonstrated that exposure to so-called TRAPs (traffic-related-air-pollutants) positively correlated with an increased prevalence of eczema flexural in both males and females”.

Pollution affects the course of atopic dermatitis

These results are in line with the results of other studies conducted in the Asian continent which demonstrate how theexposure to nitrogen dioxide in the first years of life is associated with a greater incidence of atopic dermatitis. Furthermore, the expert continues, “exposure to nitrogen dioxide and particulate matter before birth (especially in the first trimester of pregnancy) would significantly increase the risk of developing atopic dermatitis before 6 months of age. In another study it was noted that postnatal exposure to the same pollutants was also associated with reduced remission of atopic dermatitis after childhood, with persistence of the disease.”
Finally, some recent epidemiological studies conducted in China, Korea and Türkiye (2021-2022) have demonstrated positive correlations between poor air quality and medical visits carried out for atopic dermatitis in both children and adults. A study conducted in 2019 correlated the increase in dermatological visits for atopic dermatitis in adults and children with the increase in concentrations of particulate matter PM2.5, PM10, nitrogen dioxide and sulfur dioxide. The same correlation has been demonstrated with forest fire pollution, in both children and adults.
“The impact of pollution on the course of atopic dermatitis – concludes Stingeni – and the important repercussions for the NHS should be evaluated on large series of patients, correlating these data with the presence of skin disease and the severity of the symptoms. At the same time it is necessary reverse the trend in favor of environmental policies that reduce air pollution. From a clinical management point of view, it is worthy of note that some devices aimed at improving the barrier function of the skin bear the wording “anti-pollution”, confirming how clinical research on environmental pollution and atopic dermatitis is producing scientific evidence on on which therapeutic innovations for this important chronic inflammatory pathology are based”.