This article says that scientists have a plan to inject sulfur compounds into the air to thicken the air with sun reflecting gases.  Their thinking is based on the cooling period that usually follows a volcanic eruption.  However other scientists warn that this may damage the actual ozone layer and delay the repairing of the hole in the antartic by up to 70 years.  It may also increase precipitation rates as it did in an eastern country during a massive volcanic explosion.  They also fear that it will drastically change the climate patterns and even though it was not stated in the article I fear that there would be some health hazards to having so much sulfur in the air, no matter how high up it may be.

I fear that the risks far outweigh the benifits and that this plan would cause more problems than it would solve. This is a good article for my group, prevention.  Using Chemicals to Cut Global Warming May Damage Ozone Layer