Call you local and/or state health department and see what info they have. Is there a historic landfill nearby that is the source of methane and how is it getting into your house? In the meantime spend little time in the basement as that is likely were it is entering. Methane gas disipates fairly quickly although it can be a explosive hazard if high enough concentrations.
: I just found out that methane gas had been discovered in the house I am renting before we were here. My son and family have been very sick. How do you check for this and if it rains would it decrease the gas or increase it. I have no knowledge on this subject. I would appreciate and direction to gain knowledge etc.
: It would also be appreciated if it could be fast. My son is very sick and seems to be fading more and more. I also understand other than nausea, etc. that contact with this gas can effect the urinary tract?