windows are still open, and i'm noticing the same basic cause & effect as i have previously: the headache gets a lot better if i stand beside the window for a few minutes, even if it comes back afterwards.

methane - which is my concern, not carbon monoxide - is not a poison. it can't actually hurt you, in low concentrations. what it does is smother you, so you can't breathe. but, i'm obviously getting enough oxygen. so, if i'm right about what's happening, the headaches i'm getting from the methane are basically the same thing as getting woozy after climbing a mountain: i'm just experiencing low oxygen. there aren't long term side effects, or at least won't be if the exposure is kept minimal. it's just irritating.

i'm going to try and get back to work for a few hours. i don't promise much.