There are many complicated implications of climate change, but one consequence that has been indisputably measured is the depletion of the ozone layer: the part of the atmosphere that protects us from cosmic radiation. You can argue about what exactly caused it, but not that it has happened.
The depletion of the ozone layer has multiple effects on your health, primarily negative. Since exposure to sunlight causes damage to human tissue, less ozone layer leads to a higher incidence of skin and eye conditions, including skin cancer and eye lesions such as cataracts. Of course, there are numerous other consequences of climate change outside the scope of this article.
The ozone layer was discovered in 1913, and a network of monitoring stations around the world was built throughout much of the twentieth century. Stratospheric ozone depletion was first reported in 1985, and ozone levels around the world have dropped an average of approximately 4% to 6% since the late 1970s, although the areas around the north and south poles have seen much larger seasonal declines.
However, due in part, it seems, to an international treaty called the Montreal Protocol agreed to in 1997, the production of hydrocarbons that play a role in ozone depletion have been phased out and eliminated, and the ozone layer has begun to recover recently (or at least stabilized). It is estimated that it will take until 2050 for it to return to the relatively-healthy conditions of the 1980s, and above the poles until 2075.
In the meantime, even the relatively small depletion of the ozone layer has significant consequences. Ground-level ultraviolet radiation (UVR) has increased by up to 10% at mid to high latitudes over the past few decades (such as over North America), and it’s not without adverse effects.
Increased Solar UV Radiation
Sunlight consists of a spectrum of differing wavelengths of electromagnetic radiation, including ultraviolet radiation. UVR is further divided into UVA, UVB, and UVC. UVC has the shortest wavelength, and as such is completely absorbed by stratospheric ozone. UVA has the lowest energy and the longest wavelength and most passes through the atmospherem mostly undeterred to reach the surface of the earth, while about 90% of UVB (with wavelengths between UVA and UVC in length) is absorbed by stratospheric ozone. In fact, 20 times more UVA radiation reaches the earth’s surface than UVB. Yet although there are higher levels of UVA radiation, and UVA penetrates your skin more deeply than UVB, it is the higher-energy UVB portion of the spectrum that is mostly likely to be absorbed by DNA, and therefore most likely to initiate carcinogenesis in your skin. Any small decrease of stratospheric ozone has significant effects on your health.
The amount of ambient UVB radiation that hits your exposed skin while you are outdoors is dependent on a number of factors:
- Stratospheric ozone levels
- Solar elevation (due to time of day, time of year, and latitude)
- Regional pollution
- Cloud cover
- Amount of light reflected (due to the presence of reflective environmental surfaces such as water, sand, and snow)
Less ozone, a sun higher in the sky, less pollution, a higher altitude, less cloud cover, and more reflective surfaces will all increase the effective amount of UVB radiation you experience.
The Effects of Ozone Depletion on Your Skin
Stratospheric ozone depletion has a range of possible health impacts on your skin. Epidemiological studies implicate solar radiation as a cause of skin cancer—including squamous cell carcinoma, basal cell carcinoma, and melanoma—with a higher risk in individuals with fair skin. In fact, the International Agency for Research on Cancer concluded, in 1992, that solar radiation is a cause of skin cancer. And the highest risk for skin cancer is related to UVB exposure. Obviously, this is an ominous sign, with ozone depletion leading to greater ground levels of UVB.
About 86 percent of melanomas can be attributed to exposure to ultraviolet (UV) radiation from the sun. About 90 percent of nonmelanoma skin cancers are associated with exposure to ultraviolet (UV) radiation from the sun. You can find more facts about skin cancer on the Skin Cancer Foundation’s website.
In 1998, the United Nations Environmental Program projected significant increases in the incidence of skin cancer due to depletion of the ozone layer. The assessment anticipated that for at least the first half of the twenty-first century, unless individual behaviors changed on a large scale, additional radiation exposure would amplify the severity of sunburn and incidence of skin cancer. Unsurprisingly, incidences of skin cancer have dramatically increased throughout the twenty-first century. Between 1992 and 2006, treatment of nonmelanoma skin cancers increased by nearly 77 percent. The incidence of squamous cell carcinoma has increased 200% over the past three decades in the United States. The incidence of melanoma increased 1.9% between 2000 and 2009.
Scientists expect the accumulation of additional UVB exposure due to ozone depletion to cause an increase in skin cancer incidence in fair-skinned individuals living at mid to high latitudes. Scenario-based modeling that integrates emissions, ozone destruction, UVR changes, and cancer induction, indicates that European and United States’ populations will experience a 5-10% increase in skin cancer incidence during the middle of the twenty-first century.
Of course, all the other effects on your skin as a result of increased exposure to ultraviolet radiation, such as sun spots, wrinkles, and prematurely-aging skin, will also increase.
A summary of the effects of solar ultraviolet radiation on your health, as it relates to your skin, include the increased likelihood of:
- Malignant melanoma
- Non-melanoma skin cancer, including basal cell carcinoma and squamous cell carcinoma
- Chronic sun damage and skin photo-aging (such as wrinkles, sun spots, keratosis, elastosis, uneven pigmentation, etc.)
- Photodermatoses (such as melasma, polymorphous light eruption (PMLE), etc.)
The Effects of Ozone Depletion on Your Eyes
Just like for your skin, stratospheric ozone depletion has health consequences for your eyes. With increased levels of UVB radiation come increased likelihoods of adverse eye conditions.
Approximately 50% of incident UVA rays, and 3% of UVB rays, penetrate your cornea: the transparent outer layer of the eye. A further 1% of UVB is absorbed by your aqueous humor, and the remaining total ultraviolet radiation (UVA and UVB) is absorbed by your lens. It therefore makes a lot of sense that sunlight exposure is associated with common eye problems.
There is a strong association between ultraviolet radiation exposure and lens opacities, such as cataracts. While cataract formation is complex, cortical and subcapsular cataracts appear to be associated with UV exposure while others, such as nuclear cataracts, do not. In vivo and in vitro laboratory studies in various mammalian species confirm that exposure to UV rays, in particular UVB, induces lens opacification.
Acute exposure of your eyes to high levels of UV radiation, in particular where light may be reflected off surfaces such as snow, water, or sand, can also cause inflammation of the cornea and conjunctiva. These include photokeratitis and photoconjunctivitis, the equivalent of a sunburn to your eyes and commonly called snow-blindness. Pterygium, a benign growth of the cornea, is another common condition linked to chronic exposure to UVR; it is common among populations in areas of high UVR exposure. For example, in a large Australian population-based study, almost half of the risk of pterygium was attributable to sun exposure.
Other eye disorders associated with UVR are less common but still cause significant indisposition in affected individuals. For instance, acute solar retinopathy—effectively a sunburn to your retina—may present to individuals who look directly at the sun. There is also evidence that sunlight exposure (possibly the blue light component—in the higher-energy spectrum of visible light closest to ultraviolet light) may be implicated in macular degeneration.
A summary of the effects of solar ultraviolet radiation on your health, as it relates to your eyes, include the increased likelihood of:
- Cancer of the cornea and conjunctiva
- Lens opacity such as cataracts
- Uveal melanoma
- Acute solar retinopathy
- Macular degeneration
Other Effects of Ozone Depletion on Your Health
Two other general effects of ultraviolet radiation exposure that directly impact you are the production of Vitamin D, and UVR-induced immunosuppression. In these areas, the health consequences of stratospheric ozone depletion are complicated and not well understood.
On one hand, inadequate levels of Vitamin D have been implicated in a number of different diseases and conditions, including rickets, osteomalacia, osteoporosis, muscle pain, tuberculosis and other infections, certain cancers such as prostate and breast, and even hypertension and heart disease. If increased UVR exposure resulted in increased levels of Vitamin D in a marginal percent of the population who otherwise would be deficient, there could be decreased incidences of a number of these ails. This assumes, however, the absence of an adequate consumption of dietary Vitamin D sources—which alone can be enough to provide sufficient amounts of Vitamin D.
On the other hand, ultraviolet radiation exposure causes both local (in the skin and eyes) and whole-body immunosuppression. Since cellular immunity is adversely affected by UVR, increased exposure to sunlight could result in decreased immune function, increasing occurrences of infectious diseases (and their spread) and various autoimmune diseases, and the decreased effectiveness of vaccines. The impact, however, is very difficult to measure.
There are a variety of other effects of ozone depletion. Since UVR impairs optimal photosynthesis in plants, worldwide food production could be altered. As ice melts, coastal areas could change as ocean levels rise and displace people. Climates could change as air pollution increases. Of course, the results could increase violence and incite geopolitical strife over territorial disputes and access to food supplies and fresh water. But this is just conjecture; these effects can be prevented.
What You Can Do
The part that can’t be immediately changed is what will occur right now if your skin and eyes are exposed to the sun, as less ozone increases the amount of incident UVR you absorb. But you can take action to avoid the ill effects.
First of all, you can stay out of the sun, and cover up when you go in the sun. Wear sunglasses. Learn about the common myths about sun exposure. And follow the tips in this article on Summer Sun Protection.
Also, there’s something else that helps prevent sun damage that you might not realize offhand. Adverse health effects to your skin and eyes are associated with low or depleted antioxidant status, and higher oxidative stress, such as from smoking or sun exposure. These stresses create free radicals that damage tissue; antioxidants help prevent some of the damage these free radicals would otherwise cause to your body. Eating foods containing high levels of antioxidants, such as colorful vegetables and fruits, and taking a supplement or supplements containing specific antioxidants shown to prevent UVA and UVB damage, can help prevent some of the adverse effects from the sun, including in a world with a diminished ozone layer.
Stratospheric ozone depletion has health consequences. Specifically, increased UVB radiation reaching the surface of the earth increases the likelihood of skin damage, including aging and cancers, and also eye disorders, including cataracts and many other conditions. Increased ultraviolet radiation may also even increase the prevalence and spread of immune-related disorders, but this, along with any observable effect from potentially increased levels of Vitamin D production, if any, are difficult to predict.
Yet avoiding some of the adverse health consequences of increased UVR is actually within your control. Simply follow these general guidelines:
- Stay out of the sun
- Cover up when you are in the sun
- Wear sunglasses
- Follow these tips on sun protection
- Obtain your Vitamin D primarily from food
- Consume foods and supplements with high levels of antioxidants, which can help prevent UVR damage to your skin and eyes
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