Now I have to go to the lab and check (we have a ringdown sensor tuned to CH4/CO2/H2O precise into single digit ppb).

Some humans have methanogens in their gut and these people exhale methane (gut->bloodstream->lungs) and they can emit quite a lot, at least enough to completely fuck up our lab work. Our lead scientist is such a person, and the effect is so bad that he exhales into a bin liner when setting up an experiment.

Or he did: this was so inconvenient that we automated all our instruments, valves, etc so we could run experiments from the kitchen or even at home (lots of RPis which I wouldn’t normally use for anything important). Fortunately this also automated all the data collection.

But now I have to run a trial to see if my diet modulates anal CH4 emissions. Thanks HN!