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GLOBAL WARMING, OZONE DEPLETION AND HUMAN HEALTH By Hao Huang, Jun Chen and Hui Li, Under the instruction of Professor Gregory R. Carmichael December 10, 1999

Introduction	Ozone Depletion	Human Health
Global Warming	What Should We Do?	Other Sources

Our lovely Earth

Source: http://www.enviroweb.org/ INTRODUCTION In recent years, global warming and ozone depletion have become the greatest environmental challenges that human being are facing, and they have many huge impacts, on economy, on politics, and on people’s daily lives, etc. One of these impacts has been drawing more and more attention from the public, that is, the impact of global warming and ozone depletion have on human health.

The objective of this project is to briefly introduce the phenomena of global warming and ozone depletion, and their impact on human health, so that people will have clearer understanding on such issues. We have reasons to believe that if actions are not taken in time to solve the problems of global warming and ozone depletion, people will have to face more and more negative impacts. We don’t want to see the bad, even catastrophic results happen. So it’s time to do something, to protect our health, to protect our earth!

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GLOBAL WARMING

^{Global

temperature is increasing!}

It has been observed that global average temperature increased 0.3-0.6°C (0.5-1.0°F) in the last century. In the recent 30 years, it has gone up rapidly than the previous decades.

Source: EPA global warming web site.
Of course, the increase of earth's surface temperature is very small, but it really affects the earth and human beings greatly in many aspects.
With the temperature going up, the activities of all living things increases. The crops may grow faster and get higher production. Plants may grow faster and spread to larger area. Small animals such as insects and shrimps may get better living conditions and their population increases significantly. Bacteria and virus may get better living environments and reproduce faster, resulting in human diseases or cattle diseases.
Global warming also brings us more and more extreme weathers such as droughts, floods, heat waves, sand storms, tornados or typhoons.
Do not neglect such a "small increase" of earth's temperature.

Why the temperature increases?

The solar radiation keeps the earth's surface and atmosphere warm. The atmosphere functions just like a heavy coat. It is transparent to visible and violet radiation from the sun, but not to the long wavelength radiation from the Earth's surface. Without atmosphere, earth's surface temperature would be much lower than it actually is. The long wavelength radiation absorption ability of the atmosphere determines the global temperature.

The greenhouse effect is the key of global warming. The greenhouse gases include CO₂, NO_x , CH₄, H₂O, CFCs, O₃ and many other gases which absorb long wavelength radiation and make the earth warmer. Increasing their concentration will certainly increase the global temperature. Simulation shows that global temperature would increase by 1.5 K to 3 K if the CO₂concentration doubled.

Ever since the industrial revolution, people have been using coal and oil as major fuel. Finally the carbon in coal and oil enters the atmosphere in the form of CO₂ . Actually, CO₂ concentration has increased around 20%(from 310 ppm in 1950's to 370 ppm in resent years). If we keep consuming carbon fuels as we do today, we will have the CO₂ concentration doubled very soon and will see higher global temperature.

If you have further interest in Greenhouse Effect, just listen to NOAA scieintists' explaination.

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OZONE DEPLETION Ozone depletion is another severe environmental problem that human beings are facing. Ozone is a very rare gas in our atmosphere, but it is extremely important to people on the Earth. Ozone mainly exists in two regions of the Earth’s atmosphere, troposphere and stratosphere. About 90% of total ozone resides in stratosphere, which is a layer between around 10 and 50 kilometers above the Earth’s surface. Most people know about "ozone layer", which exactly refers to stratosphere. When we talk about "ozone depletion", we also mean stratosphere ozone. Stratosphere ozone is very beneficial to people, in that it absorbs most of the ultraviolet sunlight called UV-B, which has strong biologically damaging effects. It is just like a huge invisible shield, preventing the harmful UV-B from hurting us. Imagine if the ozone layer disappeared, what would happen? That would be drastically terrible! Without the filtering effect of the ozone layer, the Sun’s UV-B would reach the Earth’s surface in much greater amounts. Excessive exposure to UV-B radiation, which is harmful as mentioned above, will cause many healthy problems. Since the ozone layer is becoming thinner and thinner, there even has appeared large ozone hole over the Antarctica, the UV-B radiation has already caused people much trouble on their health. From the graph here, we can clear see that the concentration of stratosphere ozone has been decreasing over years. Now let’s take a look at the diseases related to ozone depletion.

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HEATH IMPACTS

Health Problems Related to Global Warming

Believe it or not, global warming has many effects on human health, both direct and indirect. Some people think that the warming is just a trivial issue and won’t bring great impact to human health, but they are wrong. The impact that global warming has on human health is real huge!

Let’s first take a look at the direct effects --

The temperature can greatly affect many of the biological process in human’s body. Although human biology has some abilities to make adjustments the changing temperature, it cannot completely handle all the effects it brings. In other words, the ranges of tolerance of the temperature increase are limited. High temperature can have strong negative influence on human biology, and disturb human’s metabolism and cause people to die. The elderly, the very young and those people with some specific diseases are particularly vulnerable to the extreme weather events brought by global warming. Research held in countries, such as China and the United States, and shows that higher temperature does have strong relationship on human mortality. In recent years, there has been plenty of news reporting intense heatwaves attacking cities like Rome, Athens, Dallas or New York and causing lots of people’s deaths. Here is an example. In 1995, the heatwave in Chicago killed about 500 people in a matter of days!

People can see by their own eyes that some other people die of the high temperature, so the direct health effects are sort of "visible" effects. But, the indirect effects could be "invisible", because general people may not relate some health problems to global warming. Actually, the indirect effects could be even more severe than the direct ones.

One of the most dangerous aspects that global warming has is its potential to further the spread of various infectious diseases. Global warming brings us higher nighttime temperatures and warm, which would give disease-carrying insects, such as mosquitoes and rodents, better living conditions so that some diseases could spread much faster than before. Those diseases include malaria, encephalitis, Lyme disease, cholera, and etc. Besides, global warming also shifts climate zones, so the disease-carrying insects would migrate toward the Earth’s poles. Such diseases as malaria and yellow fever may become widespread in many more countries than at present. Some of the countries may not have sufficient health services to prevent and eliminate the diseases.

Global warming could also cause more serious pollution problems, and further, bring people more health problems. Global warming could help develop more hot, stagnant conditions, which would cause smoke articles and noxious gases linger in the air for longer time. And such conditions would also accelerate some chemical reactions that generate some other pollutants, which would cause even more problems. Under such a scenario, which is sort of chain reaction, human beings would face much more risk of respiratory diseases, such as bronchitis and asthma.

Another thing that global warming could trigger more floods. Since global warming is very likely to change the precipitation patterns around the world, some regions would receive more rainfall so they would face more danger of flooding. And, the sea ice in the pole areas and the glaciers would melt as a result of the higher temperature, so the sea level would rise and the low-lying coastal areas like the Netherlands would be more prone to flooding. The floods could contaminate our water supply because they carry many pollutants washed from cities, farmlands and sewage treatment systems. If the water supply is polluted, the risk of the outbreak of infectious disease will significantly increase.

Global warming also cause health problem that has relationship with the ozone. Here, we are not talking about stratosphere ozone, but troposphere ozone. Unlike stratosphere ozone, which is beneficial, troposphere ozone is a health hazard. When closer to the ground, ozone is a major component of smog. It is a respiratory irritant that affects lung function in a manner just similar to cigarette smoke. Ozone can cause constriction of the small bronchial airways and a reduction in lung capacity, which will lead to lots of respiratory diseases. Someone even holds the view that ground level ozone could cause breast cancer, although it has not been verified.

Energy from the sun supports all life on Earth. However not every part of sunlight is beneficial to us. Some of them are even very harmful to human health. This includes the sun's burning or "ultraviolet" rays. The ultraviolet region of the electromagnetic spectrum is subdivided into three bands termed UV-A, UV-B and UV-C. It causes skin aging, wrinkles and can also damage outdoor plastics and paint. UV-B, which is stronger than UV-A, is the most harmful to us and other life forms on Earth. UV-B causes skin cancer and cataracts, a permanent clouding of the eye which reduces vision. Both UV-B and UV-A cause suntans and sunburns.

Fortunately, most of the UV radiation are filtered by stratospheric ozone layer. Such as UV-C never reaches the earth's surface because it is filtered out by the ozone layer in the stratosphere. Stratospheric Oxygen and Ozone molecules absorb 97-99% of the sun's high freguency Ultraviolet light. But to UV-B spectrum, with wavelengths between 270 and 320nm, ozone layer has a relativey weak abosorption. And in the past few years, the ozone layer has become slightly thinner than it used to be. This means slightly more of the sun's UV-B rays can now reach the earth's surface and effect us.

Exposure to excess UV-B radiation can lead many health damage to people.

Skin Damage

Skin cancer is the most common form of cancer in white populations. The incidence of skin cancer in the United States has reached epidemic proportions. One in five Americans will develop skin cancer in their lifetime, and one American dies every hour from this devastating disease. There are two basic types of skin cancer: melanoma and non melanoma.

Melanoma is the most serious form of skin cancer, one of the fastest growing types of cancer in the United States. Roughly eighteen Americans die each day from melanoma. Excessive exposure to the sun during childhood is widely accepted as a cause of melanoma, particularly for those with light skin.

Non melanoma skin cancers are less deadly than melanomas. Nevertheless, left untreated, they can spread, causing disfigurement and more serious health problems. It accounts for approximately 95% of all reported skin cancer cases. It has been confirmed that non melanoma skin cancer is caused by UV-B radiation, and further believe that a sustained 10% depletion of the ozone layer would lead to a 26% percent increase in non melanoma skin cancer. This could mean an additional 300,000 cases per year world wide.

Other Skin Damage Other UV-related skin disorders include actinic keratoses and premature aging of the skin. Actinic keratoses are skin growths that occur on body areas exposed to the sun. The face, hands, forearms, and the "V" of the neck are especially susceptible to this type of lesion.

Eye Damage

Cataracts are a form of eye damage in which a loss of transparency in the lens of the eye clouds vision. If left untreated, cataracts can lead to blindness. Cataracts account for half of the blindness in the world. About 25 million cataract operations are performed annually in the United States, where cataracts currently represent the third-largest cause of preventable blindness.

Research shows that UV-B radiation increases the likelihood of certain cataracts. Furthermore, logistic regression analysis controlling for age showed a strong correlation between cumulative UV-B exposure and cataract. This analysis indicated that a doubling of UV-B exposure will increase the risk of developing cataracts by 60%. Conversely, if the
ocular exposure to UV-B is halved, the risk is reduced by 40%.

Immune Suppression Although the detailed relationship between exposure to ultraviolet radiation and the suppression of cellular immune responses is not elucidated clearly. Scientists have found that overexposure to UV radiation may suppress proper functioning of the body’s immune system and the skin’s natural defenses. All people, regardless of skin color, might be vulnerable to effects including impaired response to immunizations, increased sensitivity to sunlight, and reactions to certain medications.

The suppression of the immune system appears to result from the altered chemical messengers arised from the effects of UV-B on the several important cells of the immune system that reside in the skin.

Above we mainly talk about the effect of stratospheric ozone on human health. In troposhere, ozone also exists, and have some negative effects on human health.

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ACTIONS

Keep the Earth Cool !

Since CO₂ contributes most to the global warming problem, great effort has been dedicated to control its emission. Solar energy and nuclear energy have been introduced to substitute fossil fuels. But fossil fuels are still the major energy sources for most countries in the would. Most developing nations rely on coal and oil as the only energy sources. The situation is that developed nations consume a lot of petroleum and release lot of CO2 consequecially. Developing nations such as China, India and African nations, need to consume more and more energy to get industrialized.

Save the Ozone Layer:

Following the discovery of the ozone hole over Antarctica in the mid-1980s, many governments and people realized the importance to save the stratosphere ozone. The first thing we should do is to phaseout ozone depletion chemicals, such as CFCs. The Montreal Protocol on Substances That Deplete the Ozone Layer is a landmark international designed to protect the stratospheric ozone layer. The Vienna Convention for the Protection of the Ozone Layer(1985) outlines states' responsibilities for protecting human health and the environment against the adverse effects of ozone depletion, established the frame work under which the Montreal Protocol was negotiated. Only when we realize the severeness and take action, can we save ourselves.

So, Act Now!

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OTHER SOURCES

1. Climate Change and Human Health, An assessment prepared by a Task Group on behalf of the World Health Organization, the World Meteorological Organization and the United Nations Environment Programme, A.J. McMicheal, A. Hanines, R. Sloof and S. Kovats, editors

2. Scientific Assessmet of Ozone Depletion: 1994, World Meteorological Organization Global Ozone Research and Monitoring Project ? Report No. 37, National Oceanic and Atmospheric Administration, National Aeronautics and Space Administration, United Nations Environment Programme, World Meteorological Organization

3. http://www.who.int/environmental_information/Information_resources/htmdocs/execsum.htm

4. http://www.acsh.org/publications/reports/global.html

5. http://www.enn.com/specialreports/climate/what.asp

6. http://www.globalwarming.org/science/index.htm

7. http://www.enviroweb.org/edf/isproblem/isproblem_frameset.html

8. http://www.heatisonline.org/

9. http://www.state.gov/www/global/oes/97climate_report/part6.html

10. http://www.state.gov/www/global/oes/97climate_report/index.html

11. http://www.epa.gov/globalwarming/impacts/health/index.html

12. http://www.epa.gov/ozone/uvindex/uvhealth.html

13. http://www.nas.nasa.gov/Services/Education/Resources/TeacherWork/Ozone/Ozone.homepage.html

14. http://gcrio.ciesin.org/ozone/ozoneFAQs.html