I. Air. Any burning or volatization of fossil fuels contaminates the air with emissions that would not naturally be there, and some uses create a worst problem than others. The change that would have the largest positive impact is the one most obvious, and per the peak oil commentators coming whether we want it or not, which is to cease use of fossil fuels. Avg Air Human Exhale 21.0% 16.3% CO2 .03% 4.0% N 78.0% 79.7% Inert/Other 1.0% NH3 5-25g/m3 4-9g/m3 II. Water. One inch of rain per square foot is around ½ gallon of H2O . Grains - Misc. Beans Fruit, dried Processed Pasta Nuts Greens gold