their basement? I have never heard that there are toxic fumes that are
produced when tig welding... if I can't weld in the basement, then
everything else doesn't really matter...

I am certainly not an exert on welding, but consider that gases do not
need to be toxic to be dangerous. We have sensors for CO2, but we do
not sense low O2. N2 at least has killed by displacing O2, by the time
the victim starts to feel dizzy, it's too late, and other inert gases
might be similarly dangerous. Please check carefully before doing TIG
in a confined space. At a mimimum, use good active ventilation. If you
plan to work on small items, a fume hood might be helpful.

Bill