Good info, fortunately it's not that, everything well ventilated here and no gas.
Discussion
you'd be surprised how many places there is somewhat dangerous levels of methane in the atmosphere tho. more common where there is earthquakes but a lot more of a danger to people than recognised.
it's mostly not a problem for me because i spend most of my time on the lower storey with a big space for methane to float upwards, but carbon dioxide/monoxide is heavier than air, and what i think was happening was the levels of CO and CO2 were building up in my space with all the windows closed.