| Monday, May 09, 2005 - 12:01 pm |
"UV would break that down and bleach the bones."
No im sorry, Ive never seen UV bleach anything organic.
Hymy, do you even know how UV damages?
Ultraviolet light is ionising, this has the potential to screw with the DNA of a cell that gets hit. While this may eventually cause a cancer, the cell does not instantly just disappear.
There are 3 different types of UV and the wavelengths are roughly 400 to 320nm for UVA, 320 to 290nm for UVB, and 290 to 200nm for UVC.
UVC has the most energy and is blocked by ozone only. When it hits a molecule of ozone, it give the ozone molceule enough energy to allow it to seperate into an oxygen molecule and a single oxygen atom. This is true of any UV.
The oxygen atom created is a radical, meaning that it has a lone pair of electrons that have not been bonded to anything. These radicals are obviously very reactive and bond with each other and the other oxygen molecules to reform ozone.
The overall effect of this is that the ozone layer is self perpetuating when exposed to UV light.
However, the hole in the ozone layer has been created by the action of chlorine radicals, released from halogenoalkanes and alkenes (mainly CFCs) when they are hit by UV light.
The chlorine radical is a catalyst to the formation of oxygen from ozone. It tips the balance in favour of producing more oxygen that there is ozone being made to replace it. A single chlorine radical can catalyse the breakdown of an estimated 10000 ozone molecules before it happens to get involved in a chain termination reaction.
However, UVB and UVA are partly absorbed by the normal atmosphere, having less energy.
If the ozone layer wasnt there, that just leaves us to deal with UVC and some small quantities of both A and B.
Standard factor 30 suncream will protect us against UVC and a lot of B. That leaves us to cope with some small percentage of the wavelength of UV light with the least energy (eg, its only barely ionising). Ive seen adverts for suncream which blocks UVA as well.
Global warming and the depletion of the ozone layer are also two seperate issues, the hole in the ozone layer is being patched up now by the atmosphere. Most of the chlorine radicals have now reached the chain termination reaction and are no longer a threat. Those that are left are not having a significant enough effect to tip the balance towards the removal of ozone.
Even if the asian nations are careless now about disposing of their CFCs it wont especially matter.
The winds are such that the hole only stays over the southern hemisphere, where I dont live.
Added to that, it is very simple and not too expensive to make the compounds which chlorine radicals can react with in this now frequently mentioned chain termination reaction to stop them removing the ozone.
I do know what im talking about, I just have a mind which usually enables me to think of wacky solutions to problems.