Ozone depletion and human health effects

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Introduction
01 Cancer
02 Ozone
03 Urban air
04 Air pollutants
05 Blue-green algae
06 Water mutagens
07 Contamination
08 Chernobyl
09 Radon
10 Medical geology
11 Renal hazards
12 Organohalogens
13 Estrogens
14 Food hazards
15 Mycotoxins
16 Poisoning
17 Genetics
18 Risk

Ordering

(Excerpt from Chapter 2)

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Ozone

The atmosphere surrounding the Earth contains a small amount of ozone (O₃), a gas with molecules consisting of three oxygen atoms bound together, instead of the two which form the normal oxygen molecule (O₂) that makes up 21% of the air we breathe. The average concentration of ozone in the atmosphere is about 300 parts per billion by volume (ppbv) that is, there are about 3 molecules of ozone for every ten million air molecules. Most of it (~90%) is contained in the stratosphere about 15 - 30 km above the Earth's surface where it is present at levels of several parts per million by volume (ppmv). If all the ozone in the atmosphere were compressed to atmospheric pressure, it would form a band ~3 mm thick. Even though it is present in such small quantities, it plays a vital role in supporting life on Earth. The natural ozone levels in the atmosphere allow most harmful solar radiation to be absorbed before it can reach the Earth's surface; ozone absorbs a significant portion of the ultraviolet light known as the UV-B, which has been linked to various types of skin cancer, cataracts and damage to the human immune system; UV-B is also known to be harmful to some crops and some forms of marine life. Any changes in the amount of radiation that penetrates to the Earth's surface as a result of the thinning of the ozone layer can have potentially serious implications for human health and ecological systems, and also for global climate.

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Mario J. Molina, Ph.D., is Institute Professor at the Massachusetts Institute of Technology in Cambridge, Massachusetts. Professor Molina has been an active researcher in global atmospheric chemistry issues for more than two decades. He has been involved in developing our scientific understanding of the stratospheric ozone layer and its susceptibility to human-made perturbations. He, together with F. S Rowland, published in 1974 in the British magazine Nature the first research article on the threat to the ozone layer from chlorofluorocarbon (CFC) gases that were being used as propellants in spray cans, as refrigerants, as solvents, etc. More recently, he has also been involved with the chemistry of urban and regional air pollution. He is also leading a multi-disciplinary project involving and integrated assessment of air pollution in megacities, aimed at improving the environmental decision making process through education and the better use of scientific, technical, and socio-economic understanding. He has received numerous awards for his scientific work, including the 1995 Nobel Prize in Chemistry, which he shared with Professor F. S. Rowland and P. Crutzen for their work in atmospheric chemistry.

Luisa T. Molina, Ph.D., is currently a research scientist in the Department of Earth, Atmospheric and Planetary Sciences at the Massachusetts Institute of Technology. She holds a Ph.D. in Physical Chemistry from the University of California, Berkeley. Dr. Molina's research interests include molecular spectroscopy, chemical kinetics, and atmospheric chemistry. She has been involved in particular with the chemistry of stratospheric ozone depletion and urban air pollution. She, together with Professor Mario Molina, proposed and demonstrated experimentally a new reaction sequence, which explain how CFCs caused the Antarctic ozone hole. Subsequently, they demonstrated in the laboratory a fundamentally new chemical reaction whereby chlorine is activated on the surface of ice cloud particles in the polar stratosphere.

Thomas B. Fitzpatrick, M.D., Ph.D., is Professor Emeritus at the Harvard Medical School in Boston, Massachusetts. Dr. Fitzpatrick received his medical degree from Harvard University, was a fellow at the Mayo Foundation and received his Ph.D. from the University of Minnesota. From 1959 to 1987, Dr Fitzpatrick was chief of Dermatology Service at the Massachusetts General Hospital as well as department head and Edward Wigglesworth Professor of Dermatology at Harvard Medical School. In 1993, the World Health Organization recognized his work with its Melanoma Program Award for outstanding achievements in the field of cutaneous melanoma for which he received a Gold Medal. The National Psoriasis Foundation honored him in 1993 for the discovery of PUVA photochemotherapy in the treatment of psoriasis. In 1997, he received the Discovery Award from the Dermatology Foundation.

Paul T. Nghiem, Ph.D., M.D., is an instructor in Dermatology at the Harvard Medical School, Dana-Farber Cancer Institute and Brigham and Women's Hospital in Boston, Massachusetts. He is also a research associate in the Department of Chemistry at Harvard University in Cambridge Massachusetts. He received a Ph.D. in cancer biology and M.D. degree from Stanford University in California. He is involved in basic science research in cancer biology in the skin, clinical dermatology, graft vs. host disease.