I would apply some comom sense fixes to your basement, paint the cynder
block wall with water proof paint and seal any cracks. All this stuff
will help keep out dampness as well. You may have to add a ventilation
system to the basement. If you have hot air heat, make sure there are
no open return ducts in the basment. You may want to hav eone open feed
duct. You want to try to establish a positive pressure in the basment
and never a negative pressure.

There are cheap test kits. I think 4 pc/li is the "legal" limit.

Mark