Through the magic of dimensional analysis we can see that 1kg of CO2 is approximately 22.7 moles. Coincidentally, 1 mole of gas at STP is 22.7 liters. So 515 li

Through the magic of dimensional analysis we can see that 1kg of CO2 is approximately 22.7 moles. Coincidentally, 1 mole of gas at STP is 22.7 liters. So 515 liters of CO2, which is a fair volume - half a cubic meter. Not enough to raise the CO2 level of a garage dangerously (assuming a standard garage is 4m by 7m by 3m) but a substantial jump - 1% or so, so you'd notice it. The other nice thing is that it's rare to have people suffocate due to high CO2 levels - it quickly becomes uncomfortable and people move to fresh air, unlike e.g. pure nitrogen, because the body is adapted to detect and alleviate high CO2 levels as a proxy for low O2 levels.