Health Risk Associated With Depletion
The following are the health risk associated with depletion;
1. Cataract
In the 1989 UNEP Environmental Effects Panel Report a static estimate was developed of the cataract risk of ozone depletion. In that effort it was estimated that the world‘s population, if subjected to a sustained 1% decrease in the ozone layer, would develop between 100,000 to 150,000 additional cases annually.
More recently, the USEPA has updated the work developed for their earlier RIA (USEPA 1988), using a quantitative model that incorporates the ozone depletion scenarios developed by the Scientific Assessment Panel (UNEP 1998).
Presented in Fig. 2.6 are the results of that effort (R. Rubenstein, personal communication). Although these estimates were developed on the basis of U S data, they should be applicable to similar populations, i.e., those that are adequately nourished, worldwide and under-nourished populations may be a greater risk.
2. SunBurn
Exposure to sunlight may lead to a reddened and painful skin. This ‘sunburn’ is mainly caused by the UV-B radiation in sunlight. Exposures to more UV-B give more severe sunburns.
An increase of sunburns by ozone depletion would be more than a nuisance; sunburn is also considered to be a risk factor for more serious effects, such as melanoma.
Analysis of available knowledge leads to the conclusion that sunburns will not appreciably increase under a decreasing ozone layer; this is due to a powerful adaptation of the skin.
A gradual thinning of the ozone layer would, for instance, lead to 20 percent more UV-B in 10 years’ time. The skin is equipped with an adaptation that can even cope with the changes in UV-B with the seasons.
These are much more drastic; in mid-latitudes, the UV-B irradiance in summer is typically 10 times larger than in winter.
Experience with phototherapy of skin diseases shows that one UV-B exposure, sufficient to cause a slight reddening, decrease the sensitivity of the skin by about 20 percent. In a series of exposures, this can be repeated many times. That is how the skin adapts to the UV-B changes with the seasons.
A calculation shows that adaptation from winter to summer irradiance requires such steps of 20 percent each. This will not change much under a UV-B irradiance increased by 20 percent due to ozone depletion.
It will in fact become a bit easier, as the winter irradiance increases more than that in summer, so that the difference becomes a bit smaller.
It is certainly possible to think of situations where adaptation cannot work in this way. For instance, if a totally un-adapted skin is suddenly exposed to full sunlight, more UV-B in the sunlight will increase the likelihood of sunburn.
Persons going on an expedition to the Antarctic ozone hole have reported experiences in this line. But such conditions are quite exceptional. By far the most sunburn arises from lack of care in going through the adaptation process. Such sunburns will not increase.
3. Other Opportunistic Infections
Although it is now adequately documented that UV radiation can modulate immune reactions in rodents as well as in humans, the impact of current levels of ambient solar UV radiation on infections in human populations is still unknown.
Currently available epidemiological are unsuited to ascertain and quantify any such effect, and given the fact that scientists have been aware of this lack of data for decades, a well- designed epidemiological study that addresses this issue is long overdue.
Consequently, we are still completely ignorant when it comes to quantifying possible effects on infections of ozone depletion.
In developing animal models for the effects of UV radiation on infections, investigators have been measuring changes in fundamental immune reactions that are associated with the course of the infection and that may also be measured in humans.
Thus, the aim is to predict UV- induced effects on human resistance to infection by measuring the relevant changes in basic immune responses after UV exposure, a so- called ‘parallelogram’ approach.
This approach is in its infancy and requires a thorough and detailed knowledge of the immunological responses that play a role in any particular infection under consideration, in order to identify the relevant measurements.
This approach also has certain limitations in that the outcome of such analysis only evaluates host resistance and does not provide complete information on the spread and course of an infection in a population.
The first conjectural calculations demonstrate that physiologically relevant exposures to solar UV radiation (e.g. 90 minutes around noon in July at 40o N) may significant hamper cellular immunity against a bacterial infection (Listeria monocytogenes) in the 5 % most sensitive individuals in a population of white Caucasians.
This result is in reasonable agreement with direct measurements of the UV-induced suppression immune reactions against simple chemicals where UVB exposures of the same order of magnitude as those calculated were found to affect a high percentage of people.
In spite of these promising developments in indirect methods for assessing UV-related risks of infection, a more direct quantitative assessment of UV-induced enhanced infection remains desirable.
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A reliable assessment of the magnitude and breadth of effects of current ambient UV levels on infections and on success rates of vaccinations appears to be a long way off, and an expansion to include the effects of ozone depletion delves even deeper into realm of human ignorance.
Mitigation with Replacement of Chlorofluorocarbons
The need for reducing the CO2 equivalent emissions will affect many sectors of the economy: energy creation, transport, buildings, industry, agriculture, human settlements.
Availability of adequate energy supply is fundamental to modern living. Currently, a major portion of the energy is generated using fossil fuels such as coal, oil, and natural gas (in decreasing order of CO2 emissions).
These will need to be replaced by low- or zero-carbon fuels, such as wind, solar, and nuclear. It is true that nuclear power generation carries with it certain risks. But in order to increase the supply of low or zero-carbon energy, attention will have to be paid to increasing safeguards.
Increased emphasis will have to be placed on developing technologies for generating energy through renewable sources. In these efforts, the technology for carbon capture and storage (CCS) will play an important role.
The CCS technology captures the CO2 produced by fossil fuels and stores it permanently underground. Another area for technological advancement will be storage of the electricity generated from renewable sources as the energy supply is intermittent.
In summary, chronic exposure to UV-B could lead to cataract of the cortical and posterior sub-capsular forms. UV-B radiation can adversely affect the immune system causing a number of infectious diseases.
In light skinned human populations, it is likely to develop nonmelanoma skin cancer (NMSC). Experiments on animals show that UV exposure decreases the immune response to skin cancers, infectious agents and other antigens.
The term solar ultra violet radiation is define as the energy emitted by the sun in the in the form of electromagnetic waves.
The UV-R, name given to the electromagnetic spectrum band between 100 and 400 nm wavelengths (1 nm = 1 nanometer = 10-9 m), corresponds to less than 10% of the total solar radiation incident on the top of atmosphere.
This small spectral radiation band is subdivided, according to recommendation of the International Commission on Illumination.
There are health risks associated with the depletion of the ozone layer; namely cataract which Environmental Effects Panel Report a static estimate was developed of the cataract risk of ozone depletion.
Other related health issues associated with the ozone layer depletion are sun burns, skin cancers and other opportunistic infections. The need for reducing the CO2 equivalent emissions will affect many sectors of the economy: energy creation, transport, buildings, industry, agriculture, human settlements.
Availability of adequate energy supply is fundamental to modern living. Currently, a major portion of the energy is generated using fossil fuels – coal, oil, and natural gas (in decreasing order of CO2 emissions).
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