Award-winning physicist Will Happer:
"Let's talk about CO2. Number one, it's not a pollutant at all. We breathe out lots of CO2. Many people are surprised to learn that they exhale about two pounds, a little more than two pounds of CO2 a day.
So, you people in this room are putting out a lot of CO2. Our breath is not that different from the output of a power plant. Power plants take in normal air, and they burn, a fair amount of the oxygen out of the air in burning coal or natural gas or oil. And the result that comes out of the stack is mostly the nitrogen that was already there, a little bit of oxygen that wasn't used up, and water vapor and CO2.
And our breath, it's very similar to the power plant. It's about four percent CO2, six percent water. Power plant has a bit more CO2 and correspondingly less oxygen.
But our breath is definitely not a pollutant."