> 'It's not pollution if it comes out of animals' doesn't make much sense.
That's not the argument I was making. The argument I was making is that the presence of CO2 in the atmosphere is part of a natural process that all living organisms, including us humans, engage in. The presence of your piss in my drink is not.
Animals exhale many volatile organic compounds when they exhale, including methanol and acetone. Does that mean those compounds are by definition not pollution?
Are those compounds present because they come from the animal's metabolism, or just because they happened to be there in the environment and the animal inhaled or ingested them?
My understanding is that ketones produced by this process normally get excreted in the urine, not by being exhaled.
That said, since these are products of the animal's metabolism, I would not consider them pollution if they're just being exhaled into the surrounding air outdoors. If you bring your animal into my climate controlled clean room and have it exhale the compounds there, that would be different--but I doubt the EPA would be the first line of defense in regulating behavior of that sort.
That's not the argument I was making. The argument I was making is that the presence of CO2 in the atmosphere is part of a natural process that all living organisms, including us humans, engage in. The presence of your piss in my drink is not.