Nice FAQ... the following doesn't seem correct though.
"Ambient air contains 21% oxygen, 78% nitrogen and 1% trace gases (which includes about 0.4% carbon dioxide)."
My understanding is that there is 280 PPM to 380 PPM (depending on where its measured) of CO2 in the atmosphere. This would be 0.028% to
0.038% of CO2 in ambient air.(i.e. 380/1,000,000 X 100 = 0.038%)
(i.e. Nitrogen 78% or 780,000 PPM... 780,000/1,000,000 X 100 = 78%)
Just thought I would let you know... after all, 0.4% (4000 PPM) would really freak out the GlobalWarmers/CarbonDioxideDemonizers/ClimateChangers/CarbonTaxers. :)