what produces the most carbon monoxide animals or machinery (cars, businesses, etc.}?

nan

Last time I checked animals only expel carbon dioxide and no carbon monoxide. So the answer I would venture is Machinery or natural events like volcanoes

Carbon Dioxide, Carbon Monoxide!

cars and lorries etc...

a real electric powered automobile that would not burn gasoline won't produce carbon dioxide generally. whether, in the event that they capture on hearth, then confident. additionally, a hybrid does burn gasoline, and does produce carbon monoxide.