Health Effects of Ozone Depletion: Immunological Effects
Ozone's unique physical properties allow the ozone layer to act as our planet's sunscreen, providing an invisible filter to help protect all life forms from the Sun's damaging ultraviolet (UV) rays. Without the protective effect of ozone, life on Earth would not have evolved the way it has. The ozone layer protects us from the harmful effects of certain wavelengths of ultraviolet (UV) light from the Sun.
Because skin is an important immunological organ, the immune system is vulnerable to modification by environmental agents, including UV-B radiation. Demonstrations that immunity can be perturbed by exposing skin to UV radiation raise the concern that ozone depletion might adversely influence immunity to infectious diseases. The danger to our immune system from ultraviolet radiation comes mainly from the UV-B range of the spectrum, although UV-A poses some risk if exposure is long enough. Any significant decrease of ozone in the stratosphere would result in an increase of UV-B radiation reaching the Earth's surface, and a weakening of immunity against disease.
UV-B and the Immune System
UV radiation from the Sun can benefit health, generating vitamin D production in the skin. The required amount of radiation is, however, quite small: in summer, an exposure of 15 minutes to the hands and face is adequate. Vitamin D is also found in food. A normal diet will provide enough vitamin D for people even in winter. In the treatment of some skin diseases such as psoriasis, UV radiation is being effectively exploited. Under a doctor's control, the benefit from the treatment is much greater than any consequential increase in skin cancer risk.
However, over exposure to UV-B radiation can impair the body's ability to fight off disease, in addition to causing cancer and a range of eye disorders. UV-B suppresses the immune system, irrespective of skin colour, making it easier for tumours to take hold and spread.
Ultraviolet radiation suppresses allergic reactions of the skin and affects the immune system. When skin has been over-exposed to ultraviolet radiation, the activity of antibody-producing white blood cells is suppressed. These effects are not restricted to the part of skin actually subject to exposure, but may also occur on shielded parts of skin and in the whole immune system. As a result, the body fails to produce the antigens required for defence against a variety of diseases. This could have serious consequences, including a much diminished effectiveness of vaccinations.
At the present time, the significance of the immune system weakening caused by UV radiation is not properly understood. The weakening can possibly act to promote the development of skin cancers and worsen infectious diseases stemming from bacteria, viruses and tropical parasites. It may also activate viruses already present on the skin, such as herpes, and lead to an increase in diseases like measles, malaria, tuberculosis, leprosy and fungal infections, all of which have a stage involving the skin. People carrying the herpes virus should protect their faces against strong sunlight.
Ozone Depletion and the Immune System
Scientific research suggests that sunburn can alter the distribution and function of disease-fighting white blood cells in humans for up to 24 hours after exposure to the Sun. In addition, repeated exposure to UV radiation may cause more long-lasting damage to the body's immune system. Whilst little research has been conducted on the effects of decreasing stratospheric ozone on human immunity, it is likely that continued destruction of the ozone layer will lead to further health complications, in addition to skin cancers and eye disorders, as a result of the suppression of our ability to fight off disease.