isnt radon an issue in some parts back east?
if you did have some weird stuff like radon or carbon monoxide, and assuming the pond is in a low spot, would it be feasible to get a (free) check from the county (for human health and safety reasons), have a county guy to come out and test for methane, radon, and CO?
i think i'd want to at least know if it was normal air trapped from pond construction or something else.
