i would like details on how fl[uoro]carbon[s] affect the ozone layer. please include the components of this gas. I would also like to know where these fluorocarbons come from and what we can do to prevent this exposure.

thank you for your time

cecilia johnson 6th grader

-- CECILIA SHA'NA JOHNSON (ewilliams526@cs.com), May 11, 2000

Answers

Response to How does flourcarbon affect the ozone layer?

I've been impressed by:

http://www.atm.ch.cam.ac.uk/tour/

The main point is that fluorocarbons are catalysts: they greatly speed up the processes by which ozone breaks down in the atmosphere, and because they are not themselves destroyed in ozone-breaking reactions one molecule of CFCs can help destroy a lot of ozone molecules.

In a little more detail, the process of accelerated ozone depletion begins when chloro-fluoro-carbons [CFCs] and other ozone-depleting substances leak out into the atmosphere. Winds quickly distribute the gases evenly throughout the lower atmosphere. CFCs are extremely stable, and they do not dissolve in rain, so they stay in the atmosphere and some of them gradually gain height. After a period of several years, CFC molecules reach the stratosphere, about 10 kilometers above the Earth's surface, where the ozone layer is.

Strong ultraviolet light breaks apart the CFC molecules. CFCs release chlorine atoms, and it is chlorine (and its cousins flourine and bromine) that destroy ozone by pulling the third oxygen atom away from the other two in the ozone molecule. One chlorine atom can destroy up to 100,000 ozone molecules before it finally falls out of the stratosphere

Ozone is constantly being produced and destroyed in a natural cycle in the stratosphere. What the presence of chlorine does is it accelerates the destruction process, and so the concentration of ozone falls and stabilizes at a lower level--the more chlorine, the lower the level.

Since ozone filters out ultraviolet radiation, less ozone means higher ultraviolet at the surface. The more depletion, the more skin cancer, cataracts, damage to materials like plastics, and harm to crops and sea life.

This threat is not something that life has evolved to cope with...

-- Bradford DeLong (delong@econ.berkeley.edu), May 13, 2000.

Response to How does flourcarbon affect the ozone layer?

The EPA has a website that is a good starting point: http://www.epa.gov/docs/ozone/science/science.html

BTW, the spelling is fluorocarbon. If you have a web search function try looking for "ozone" & "fluoro"

Good luck,

-- Duane K (dkucheran@creo.com), May 11, 2000.

to add to bradford delongs answer, as chloroflurocarbons are broken down by high frequencies of electromagnetic radiation (corresponding to bond enthalpies) free radicals are produced. these react with ozone depleting in the following mechanism (where x is a free radical): x + O3 = XO + O2 ...and then.. XO + O = X + O2 the fact that a radical remains after the conversion of ozone to oxygen is the problem. radicals remain in the atmosphere indefinitely. also the speed of the catalysis is high, Cl atoms can catalyse propagation reactions at 1500 times the speed of oxygen radicals

-- Alex Martin (ac_martin@lycos.co.uk), August 10, 2002.