Radon can not be seen, smelled, really felt, or otherwise detected, apart from with a test. That's why, according to the EPA, the only method to know without a doubt if you have a radon problem is to test.
Does opening windows reduce radon?
Opening windows improves air circulation and ventilation, get more info helping move radon out of the house and mixing radon-free outside air with indoor air. Opening basement windows helps reduce negative air pressure, diluting radon with clean outdoor air.