posted on Apr, 19 2007 @ 02:03 PM
Just out of curiosity I performed numerous internet searches to determine the annual CO2 loading to the atmosphere from human respiration. I could not
find one single resource that provided this statistic so I tried to calculate it myself. I was interested in this to get an idea of the ratio of CO2
loading between fossil fuel combustion and respiration.
Global CO2 loading per year based on hydrocarbon use and cement production is 22.8 billion metric tons.
Some basic figures for calculating CO2 loading from human respiration:
Average human respiration rate = 3 l/min air
CO2 content of atmosphere = 0.038%
CO2 content of exhaled breath = 4.7%
The average human inhales 0.0009 l of CO2/min and exhales 0.141 l CO2/min. Net exchange = (+) 0.1401 (say 0.14 l)
What's the mass of 0.14 l of CO2? From any Chemistry book we find that at STP the density of gaseous CO2 is 1.98 kg/M3. This converts to 0.00198
kg/l. So one average human exhales 0.14 l of CO2 per minute @ 0.00198 kg/l. This gives 0.00027 kg/min/person = 145.6 kg/year/person
About 5 billion people in the world gives us 1.4ee(11) kg/year CO2 produced by human respiration.
That's 140 billion kg/yr
That's 140 million metric tons/yr
That's alot of CO2 however its miniscule in comparison to hydrocarbon combustion emissions.