United Nations Environment Programme, Environmental Effects Assessment Panel†
First published on 23rd November 2007
This year the Montreal Protocol celebrates its 20th Anniversary. In September 1987, 24 countries signed the ‘Montreal Protocol on Substances that Deplete the Ozone Layer’. Today 191 countries have signed and have met strict commitments on phasing out of ozone depleting substances with the result that a 95% reduction of these substances has been achieved. The Montreal Protocol has also contributed to slowing the rate of global climate change, since most of the ozone depleting substances are also effective greenhouse gases. Even though much has been achieved, the future of the stratospheric ozone layer relies on full compliance of the Montreal Protocol by all countries for the remaining substances, including methyl bromide, as well as strict monitoring of potential risks from the production of substitute chemicals. Also the ozone depleting substances existing in banks and equipment need special attention to prevent their release to the stratosphere. Since many of the ozone depleting substances already in the atmosphere are long-lived, recovery cannot be immediate and present projections estimate a return to pre-1980 levels by 2050 to 2075. It has also been predicted that the interactions of the effects of the ozone layer and that of other climate change factors will become increasingly important.
The main beneficial effect of UV radiation on human health is the synthesis of vitamin D in the skin. The action spectrum for vitamin D production14 is confined mainly to the UV-B region. Therefore, vitamin D-weighted UV radiation shows even larger summer/winter contrasts than the UVI. Despite the increases in UV-B that have occurred due to ozone depletion at mid to high latitudes in both hemispheres, any wintertime deficiencies in vitamin D-weighted UV radiation are unlikely to have been ameliorated (see under Health, below). Monthly climatological maps of the mean vitamin D-weighted UV radiation, and various other biological weightings, are now available.15 However, it should be noted that information about the action spectrum for vitamin D production is still incomplete.
Footnote |
† List of contributing authors in alphabetical order: Anthony Andrady, Pieter J. Aucamp, Alkiviadis F. Bais, Carlos L. Ballaré, Lars Olof Björn, Janet F. Bornman (Co-Chair), Martyn Caldwell, Anthony P. Cullen, David J. Erickson, Frank R. de Gruijl, Donat-P. Häder, Mohammad Ilyas, G. Kulandaivelu, H. D. Kumar, Janice Longstreth, Richard L. McKenzie, Mary Norval, Nigel Paul, Halim Hamid Redhwi, Raymond C. Smith, Keith R. Solomon (Secretary), Barbara Sulzberger, Yukio Takizawa, Xiaoyan Tang (Co-Chair), Alan H. Teramura, Ayako Torikai, Jan C. van der Leun (Co-Chair), Stephen R. Wilson, Robert C. Worrest and Richard G. Zepp. |
This journal is © The Royal Society of Chemistry and Owner Societies 2008 |