Hopefully your agent gave you a pamphlet regarding radon gas, so you at least have a decent background on what it is and how it may affect you. The current EPA threshold is 4.0, so .9 is no reason for concern and remediation is not recommended at this level. If you meant 9.0, than you may want to read your contract to see what your options are. When results come in high here in Ohio, many buyers end up having the seller either install a mitigation system ( $800-$1200 ) or reduce the price of the home accordingly. Radon is actually pretty common throughout the country. We suggest to do some research so that you feel comfortable with situation. Good luck.
You said your reading was .9 which seems within normal range. (unless you meant 9.0)
Mitigation is a fairly easy process........pvc piping is run around the perimeter of the basement, and with the use of fans, the gas is directed up and out of the building, usually through the roof. The company who performs the mitigation will then retest to make sure the readings are in the acceptable range (under 4.0).
In my area, the seller always pays for this - I have never heard of a buyer being repsonsible for the remediation, as it is a health issue, and should be addressed before closing. In my area, also, most attorneys automatically add a clause to the contract whereby the buyer has the right to walk away if the radon levels are over 4.0
This is not really, in my opinion, a reason not to buy a home. Many people are probably living with radon and don't even know it. Usually people don't test for it until their home is being sold. Once it's discovered, it can be corrected.
Hope this has helped!
Prudential NJ Properties