Clean air and skin health
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Graceful Lilly realises that it's common knowledge that clean air equals clean lungs and bodies. It's the air we breathe. But did you know there is a direct correlation between the clean air we breathe and our skin?
A quick Google search Graceful Lilly this response "Clean air is essential for respiratory health. Air pollution can lead to various health issues, including asthma, lung cancer, cardiovascular diseases, and other serious conditions. Reducing exposure to pollutants can significantly improve overall health and increase life expectancy."
OK, so that's our internal organs. But did you know how it affects the body's largest organ, the skin?
"Ambient air pollution is a known public health hazard that negatively impacts non-cutaneous organs; however our knowledge regarding the effects on skin remains limited. Current scientific evidence suggests there are four mechanisms by which ambient air pollutants cause adverse effects on skin health: (a) generation of free radicals, (b) induction of inflammatory cascade and subsequent impairment of skin barrier, (c) activation of the aryl hydrocarbon receptor (AhR), and (d) alterations to skin microflora. In this review, we provide a comprehensive overview on ambient air pollutants and their relevant sources, and highlight current evidence of the effects on skin.
Keywords: Ozone, traffic related pollutants, outdoor air pollutants, inflammatory skin reaction, oxidative stress, skin aging, cutaneous microflora
Introduction
It has long been recognized that environmental exposures affect the health of skin. Ultraviolet (UV) radiation from sunlight has been the most studied environmental hazard and its consequences on skin are well established.1–3 Another potentially serious, yet less recognized, environmental exposure is ambient (outdoor) air pollution. In 2014, the US Environmental Protection Agency (EPA) reported that over 142 million Americans live in areas where the air quality fails to meet the National Ambient Air Quality Standards.4 In the same year, the World Health Organization attributed seven million premature deaths to air pollution exposure and designated air pollution as the “world’s largest single environmental health risk.”5 Numerous studies have unmasked the deleterious effects of air pollutants on internal organs.6–8 However, our knowledge regarding the effects on skin health remains limited. In this review, we provide an overview on ambient air pollution and highlight current evidence that suggests air pollution may have adverse effects on skin health.
Ambient air pollutants and sources
Outdoor air pollution is comprised of organic and inorganic substances that are introduced into the atmosphere and pose a health hazard to humans and the ecosystem. Pollutants are derived from natural and anthropogenic sources. The EPA has designated six criteria pollutants (Table 1) that are routinely monitored: (a) ground-level ozone, (b) particulate matter (PM), (c) sulfur dioxide (SO2), (d) lead (e) carbon monoxide (CO), and (f) nitrogen oxides (NOx,) which includes nitric oxide (NO), nitrogen dioxide (NO2), and nitrous oxide (N2O).
Gaseous Pollutants
NOx, CO, SO2, ozone, and volatile organic compounds (VOCs) are the most common gaseous pollutants.9 They are mainly derived from the combustion of fossil fuels (i.e., coal, petroleum and natural gas). Ozone is formed in the atmosphere from chemical reactions involving NO2, VOCs, and UV light. CO is an odorless, colorless gas produced from incomplete combustion of fossil fuels. Common sources of CO include fuel-burning devices, such as automobiles, power generators, and boilers. CO is also a well-known byproduct of tobacco smoke.10 SO2 is a highly reactive compound generated from the processing of sulfur containing materials such as crude oil and coal.9
Persistent Organic Pollutants
POPs are compounds resistant to environmental degradation that are capable of long-range transport and bioaccumulation in humans and animals. Common POPs include pesticides, dioxins and dioxin-like polychlorinated biphenyls. Dioxins are highly toxic compounds with an estimated half-life of 7–11 years.11 They are byproducts of industrial processes such as smelting, chlorine bleaching and manufacturing of herbicides and pesticides. They are also naturally produced in volcanic eruptions and forest fires. Over 400 types of dioxins-related compounds have been identified with 2,3,7,8-tetrachlorodibenzoparadioxin (TCDD) considered the most toxic.11 These compounds are widely distributed in the environment with highest concentration in soil and lower concentrations in the air. Airborne dispersion of dioxins may result in bioaccumulation in plants and food products by binding to lipids and lipid membranes.12
Particulate Matter
PM is a complex mixture of liquid and/or solid droplets suspended in gas. Coarse particles (PM10) are between 2.5µm–10µm in diameter. They are components of dust, soil, and dusty emission from various industries. Fine particles (PM2.5) measure <2.5µm in diameter and are emitted from open fires, power plants, and automobile exhaust.9 Ultrafine particles (PM0.1) measure <0.1µm in diameter and are associated with emission from modern-day diesel powered engines. Currently, regulatory standards for PM0.1 do not exist, although these particles are emerging as the most abundant particulate pollutants in urban and industrial settings.13 PM0.1 may pose health hazards by penetrating endothelial tight junctions thereby gaining direct access to the interstitium and vascular system. This may adversely affect the pulmonary and cardiovascular system.7, 13, 14 In addition to gaining systemic access, PM0.1 and other PMs are known to exert deleterious effects by acting as a “Trojan Horse” and carrying additional toxic compounds on their surface, including bacteria, carcinogens, acids, POPs, and metals.9
Heavy Metals
Heavy metals such as cadmium, lead and mercury are common air pollutants that pose health hazards due to bioaccumulation.9 Volcanoes, waste incineration, cement, iron and steel production are relevant sources of airborne cadmium and lead particles. Lead is also emitted from the combustion of leaded-gasoline, which has been banned in many developed countries, but continues to be used in certain developing countries.15 Mercury is a component of the Earth’s mantle that evaporates from the surface of the sea. Other sources of airborne mercury particles include the combustion of coal and other fossil fuels.15
Traffic-Related/Other Toxic Pollutants
Traffic-related pollution (TRP) is a mixture of pollutants derived from the primary emission of gasoline- and diesel-fueled vehicles. TRP contains carbon dioxide (CO2), CO, NOx, VOCs, PM, lead and other toxic chemicals such as formaldehyde and 1, 3-butadiene.16 Urban communities and neighbourhoods located near busy roads are exposed to high levels of TRP. Besides TRP, there is an extensive list of other toxic pollutants,17 which includes polycyclic aromatic hydrocarbons (PAHs), benzene, and asbestos.
Proposed mechanisms for direct skin toxicity
The exact mechanism by which ambient air pollutants cause skin damage has yet to be elucidated. Based on current evidence, there may be four potential mechanisms that account for the deleterious effects on skin: (a) generation of free radicals, (b) induction of inflammatory cascade and disruption of skin barrier, (c) activation of the aryl hydrocarbon receptor (AhR), and (d) alterations to skin microflora." https://pmc.ncbi.nlm.nih.gov/articles/PMC5916788/