CO2 loading from respiration

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.

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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.

Where have you found respiration rate of 3l/min? Even little child may have a respiratory rate of 20-30 breaths per minute and with tidal volume vt=0.2 l it would mean at least 4l/min. In case of adult it would be: a tidal volume vt=0.5-0.75l and respiratory rate of 12-20, and that is of course when an adult is resting. It would give you 6-10l/min. So finally you would get at least 290kg/year/person. You also made a mistake because even with 146kg/year/person (0.146t)and 5 billion people you will get 730 million tones/year. World population is much closer to 7 billion people now- approximately 6,7 billion. Given this and 290kg/person your final result would be close to 2billion tons of co2 per year.

Interesting. Are there any industrial pollution sources or industires currently regulated by any of the various governments that produce less CO2 per year than that?