[eesmith]

Yes to both.

A Google Scholar search based on "carbonic acid gas" and "coal" found Babington, William. "A case of exposure to the vapour of burning charcoal." Medico-chirurgical transactions 1 (1809): 83. at https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2128797/pdf/med... :

> When carbon in combustion combines with oxygen we obtain carbonic acid gas, and at the same time in proportion to its moisture, more or less hydrocarbonous gas is evolved.

A Google Scholar search based on "carbonic acid gas" and "exhalation" found Allen, William, and William Hasledine Pepys. "XVII. On the changes produced in atmospheric air, and oxygen gas, respiration." Philosophical Transactions of the Royal Society of London 98 (1808): 249-281. at https://royalsocietypublishing.org/doi/pdf/10.1098/rstl.1808... with quotes like:

> In this experiment we meet with a remarkable fact, viz. that as much carbonic acid gas was given off in 5½ minutes, as in the former experiment in eleven minutes ; so that it appears, whenever atmospheric air is taken into the lungs, it returns charged with about 8 per cent, carbonic acid