Detecting presence of Radon gas

I am contemplating finishing the basement and was surprised to hear comments about the possibility of Radon gas in certain basements of homes.
How can I tell, with certainty, if there is presence of Radon gas in my basement?
Thanks

 

[georam]

Please visit a website at

http://www.radon-gas.org/index.html

It has excellent referral on how to detect, carry out test, as well as other reading materials about Radon in your basement.

Professionally, some geo-environmental companies can do sampling and testing for you. The website also suggests for "do it yourself" evaluation and to send the test to the lab.

Hope that this helps