Another math time! And again, it is closely related to GW area.
Currently (as of year 2007), human population on earth is 6.6
billion (via wikipedia). I went around to look for how much CO2
is exhaled out per person, and 2 claims were found (both via
wikipedia): claim#1: an average person’s respiration generates
approximately 450 liters (roughly 900 grams) of carbon dioxide
per day (CO2#Human_physiology) I use the standard chemistry
textbook theory (standard molar volume) to check this claim,
450L for 900 grams of CO2, and it is tallied. Thus, the amount
of CO2 released by human per day is 0.9 kg/day claim#2: In an
average resting adult, the lungs take up about 250ml of oxygen
every minute while excreting about 200ml of carbon dioxide.
(Respiratory_system) So, 200 ml per minute and thus 200 ml x 60
X 24 = 288L Or equivalent to 565.36g/per day = 0.565 kg/day
(after divide with standard molar volume constant and times with
CO2 molar weight). Apparently claim#2 has lower CO2 emission
compared to claim#1, but I w