Interesting and Useless

The average person uses about 260 kg of molecular oxygen per year, give or take.

The average tree produces 115 kg of oxygen per year (older trees produce less because they aren't expending energy on growing, the same way that Taco Bell looks great to a 17-year-old, but disgusting to a 45-year-old).

The average acre of forested land produces about 4700 kg of oxygen per year. That means that there are, on average, 40 trees per acre.

Anyway, the reason I bring this up: If you want to do your part for global warming, plant three trees. You'll even produce a net oxygen credit.

If you have to drive somewhere to visit your trees, you should probably plant 6 of 'em. You know, be on the safe side and all.