Air pollution occurs when extreme amounts of lethal gases, particulates, and organic compounds gain entry into the atmosphere.
Man-made activities and natural phenomenon can both bring about air pollution.
The major pollutants that degrade air quality are gases like carbon dioxide, sulphur oxides, and carbon monoxide, as well as volatile organic compounds.
Chlorofluorocarbons, toxic metals, ammonia, and radioactive pollutants also worsen the air quality and contribute to air pollution.
Air pollution is known to have an adverse effect on the health and well-being of the general population.
The 2014 report of the World Health Organization report stated that in 2012, air pollution had caused the deaths of approximately 7 million people across the globe.
The most alarming man-made sources of air pollution are fossil fuel combustion, vehicular sources, and aerosols, such as spray paints.
Prolonged contact with noxious air pollutants released by vehicular exhausts and the burning of fossil fuels has a damaging effect on the human body.
Such exposure can lead to severe dysfunctions including respiratory and cardiovascular diseases, irritation of the eyes and skin, neuropsychiatric problems, and even cause cancer.
This article provides an insight into the skin problems caused by short- and long-term exposure to toxic air pollutants.
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Skin Problems caused by Air Pollution
Numerous reports have revealed the direct link between contact with severely polluted air and the rising number of cases of skin conditions. Several studies have acknowledged the association between volatile organic compounds found in the air and the risk of developing chronic skin conditions.
Atopic dermatitis or eczema is often caused due to the exposure to air pollutants, such as VOCs and particulate matter. Suspended particulate matter in the air also leads to premature ageing of the skin.
Research has shown that excessive exposure to cigarette smoke can enhance the likelihood of suffering from immune-mediated disorders, such as psoriasis.
Contact with polyaromatic hydrocarbons (PAHs), often found in diesel exhaust emissions, can lead to the development of inflammatory acne vulgaris. Constant contact with environmental carcinogens can also bring about alternations in the skin cells, causing cancer.
1. Air Pollution Causes Atopic Dermatitis
Atopic dermatitis is a chronic inflammatory skin condition that typically affects young children.
Atopy is an allergy wherein the body produces heightened amounts of antibodies in response to minute amounts of certain environmental stimulants, such as pollen, dust mites, and food allergens.
Atopic dermatitis is also referred to as eczema and is manifested as itchy, inflamed, and cracked skin.
Clear fluid might be secreted from the cracked areas. The lesions of atopic dermatitis might get formed due to an imbalance in the immune system or due to a defective skin barrier.
While the condition might happen at any age, it usually affects children. Individuals suffering from it may also develop hay fever or asthma.
The exact underlying cause is unknown but researchers believe that it involves genetics because if one identical twin is affected, there is almost an 85% chance that the other will also develop it at some point or another.
Recently, environmental exposures to toxic pollutants have also been reported to cause eczema.
How does air pollution cause atopic dermatitis?
A 2014 review by the Sungkyunkwan University School of Medicine assessed the role of several air pollutants in the development of atopic dermatitis.
The evidence implicated that a host of toxic particles, such as environmental tobacco smoke, formaldehyde, toluene, volatile organic compounds (VOCs), nitrogen dioxide, and particulate matter (PM), can trigger or aggravate eczema.
These pollutants usually induce oxidative damage of the skin cells, either by disrupting the skin barrier or by affecting the normal functioning of the immune cells.
Either way, the result is a chronic inflammatory response that severely degrades the quality and functioning of the affected area.
Barring outdoor pollution, air quality inside homes is also a major risk factor as it might have dangerously high concentrations of pollutants like VOCs.
This issue was explored by the Seoul National University Bundang Hospital in their 2014 study, wherein 31 children with atopic dermatitis were exposed to different indoor environments containing varying levels of VOCs and formaldehyde.
The results showed that children in more polluted indoor environments recorded aggravations in their skin conditions.
It was inferred that high levels of toxic pollutants induce an inflammatory state that exacerbates the already inflamed skin of the affected individuals.
Air pollutants like VOCs play a major role in inducing oxidative damage of the skin to promote diseases like atopic dermatitis (eczema).
2. Air Pollution Accelerates Premature Ageing
Skin ageing is an intricate biological process affected by a combination of internal and external factors.
However, premature ageing denotes unnaturally early ageing , which can be treated and managed with professional skin care.
While the major cause of the onset of early skin ageing is environmental change, poor lifestyle choices, as well as certain medical conditions, can accelerate the process.
All these factors together bring about the structural and physiological changes in each layer of the skin, which cause alterations in the appearance especially on the exposed areas.
Prematurely aged skin is dry and wrinkled with mottled discolouration, dullness, roughness, and loss of elasticity .
Premature skin ageing is manifested as dry, sagging skin with several fine lines, wrinkles, and sun spots. Individuals also exhibit sensitivity and inflammation. Barring genetics and lifestyle choices, environmental factors such as air pollution and exposure to the UV rays of the sun also accelerate the ageing process.
How does air pollution accelerate premature ageing?
In the 2012 review by the IUF–Leibniz Research Institute for Environmental Medicine, the major effects of environmental factors on premature skin ageing was evaluated.
The evidence implicated that increased UV radiation coupled with cigarette smoke and particulate matter (PM) accelerated the process of skin ageing even in the youth.
In fact, an experimental study by the University of California, Davis, had already investigated the pro-aging effect of one of the major air pollutants, ozone, back in 2003.
According to the study, ozone-induced oxidative damage of the uppermost layer of the skin and brought about cellular stress responses in the lower layers. Both of these factors accelerate ageing of the skin.
In a recent German study, it was established that airborne particulate matter (PM) plays a major role in bringing about premature skin ageing.
They do so by promoting the generation of the reactive oxygen species (ROS), which damage the protective layer of the skin and enhance the appearance of pigmented spots, fine lines, and wrinkles.
ROS-activated oxidative damage of the outer layer of the skin is the major reason for accelerated skin ageing brought about by pollutants like ozone and particulate matter (PM).
3. Air Pollution Causes Psoriasis
Psoriasis is an enduring, repetitive, immune-mediated disorder of the skin and the joints. It usually has a substantial negative impact on the emotional and psychosocial well-being of the individuals affected by it. While psoriasis is prevalent worldwide, it occurs more in certain specific ethnic groups.
The diagnosis of psoriasis is chiefly clinical and there are several different categories of psoriasis.
The most common type is chronic plaque psoriasis which affects almost 90% of the patients with the condition.
The characteristic feature of this type of psoriasis is well-differentiated, symmetric, red plaques surrounding by blood capillaries, which have an overlying silvery scale.
While the underlying cause is often genetic, environmental factors, such as air and water pollution can also play a part in the development of the disease.
How does air pollution cause psoriasis?
According to a 2017 review published in the journal, Scientific Reports, cadmium is an air pollutant that brings about psoriasis.
Cadmium has the ability to influence the immune system in a negative way and bring about an inflammatory response which is one of the hallmarks of psoriasis.
Another recent review by the National Institute of Pathology-ICMR assessed the role of air pollutants in damaging the integrity of the skin.
It was found that exposure to cigarette smoke, which contains carbon monoxide, oxides of nitrogen, and toluene, increases the risk of developing inflammatory diseases like psoriasis.
Several studies have confirmed that psoriasis is triggered by a variety of environmental factors, all of which adversely affect the proper functioning of the immune cells (particularly, dendritic cells and macrophages) resulting in a chronic state of inflammation that is responsible for the red plaques associated with the disease.
Psoriasis is caused by exposure to cigarette smoke as the components affect the function of the immune system and bring about inflammation.
4. Air Pollution Increases the Risk of Acne
Acne, formally known as acne vulgaris, is an inflammatory disorder of pilosebaceous units (i.e. hair follicle and associated sebum gland) and generally occurs during puberty.
The typical lesions are black and white comedones (small bumps), swollen papules, and pustules, which might leave scars and changes in pigmentation.
The mechanism of acne is multifaceted and involves abnormal proliferation of skin cells (keratinocytes), increased secretion of sebum which is a waxy/oily substance, invasion by colonies of Propionibacterium spp, and chronic inflammatory response.
The acne pustules commonly occur on the face, neck, chest, as well as upper back.
Medical history and clinical examination can help in determining the underlying cause of acne, such as side-effects of medication, hormonal imbalances, or even exposure to environmental pollutants.
How does air pollution increase the risk of acne?
A 2017 review by the IUF – Leibniz Research Institute for Environmental Medicine studied the link between air pollution and the development of acne vulgaris. It established that pollutants play a significant role in causing inflammatory acne.
This review was based on a collaborative study between the University of Buenos Aires and the University of Ferrara.
The latter showed that airborne particulate matter generates reactive oxygen species (ROS), which can penetrate the tough outermost layer of the skin.
This initiates a cascade of reactions which generate more inflammatory molecules resulting in the formation of acne lesions.
Several studies have reported that diesel exhaust emissions containing polyaromatic hydrocarbons (PAHs) also induce the inflammatory response that contributes to the formation of acne.
Air pollutants, such as particulate matter and PAHs, generate an inflammatory response which causes acne vulgaris.
5. Air Pollution Triggers Skin Cancer
The cancers that arise from the tissues of the skin are referred to as skin cancers.
They are caused due to the formation of abnormal cells which have the capacity to intrude or spread to different parts of the body.
Basically, there are three main types of skin cancers: squamous cell skin cancer (SCC), basal cell skin cancer (BCC), and melanoma.
SCC and BCC, along with a few lesser known skin cancers, comprise the group referred to as non-melanoma skin cancer (NMSC).
The BCC grows steadily and destroys tissue surrounding it but is unlikely to reach distant parts or result in death. It often manifests as a painless protruded patch of skin, that might be shiny with small blood vessels surrounding it. BCC might also resemble an ulcer.
Over 90% of the cases are caused by undue exposure to the UV (ultraviolet) radiation of the sun.
This enhances the risk of all the three major types of skin cancer by causing genetic changes and mutations. Environmental pollutants also act as carcinogenic agents that might bring about cancer.
How does air pollution trigger skin cancer?
A 2002 review by the Laboratoire de Biologie Cellulaire studied the role of air pollutants in triggering skin cancer. It was found that UV radiation is the main agent that causes alterations of the genes.
Vehicular emissions containing polyaromatic hydrocarbons (PAHs) also bring out changes in the skin that cause cancerous growth.
In line with this review, another 2012 study by the Oregon State University established that PAHs act as skin carcinogens, particularly by reacting with the DNA to form products that affect the integrity of the skin and initiate tumour formation.
A recent review by the Nicolaus Copernicus University in Torun also proved that particulate matter (PM) have a carcinogenic effect on the skin.
Air pollution also triggers skin cancers because of high ambient levels of potential carcinogens, such as PAHs and PM.
To summarize, it can be said that a host of skin problems are caused by exposure to air pollution. Volatile organic compounds cause oxidative damage to the skin’s barrier and promote the progression of atopic dermatitis.
Particulate matter pollution causes the generation of free radicals that damage the outer layer of the skin bringing about premature skin ageing.
Exposure to cigarette smoke affects the immune system resulting in inflammatory damage and psoriasis. Polyaromatic hydrocarbons and airborne particulates initiate chronic inflammation leading to acne vulgaris. Finally, air pollutants act as carcinogens and trigger skin cancers, such as basal cell carcinoma.