Radon & Negative Pressure
Some rare new homes may have systems to pressure the building positively .
A house in a negative pressure can suck air directly beneath it and generally up to 10 meters around its perimeter . This area could become even larger when the soil gas beneath the houseʼs perimeter cannot find a connection to the outside . For example , when around the building is covered by asphalt . Radon comes from the foundation , mostly ( NOT Always !), there would be a higher Radon level in the basement . However , there is no predictable ratio between the basement and upper floors .
Even with the negative pressure , the source ( i . e ., Radon in the soil gas ) and the pathway are still needed to have Radon in the house !
POSITIVE PRESSURE
When air blows from outside into the house creates positive pressure . The positive pressure pushes the soil gas back and does not let Radon come inside . In this case , besides retarding the soil gas entry , it also provides some dilution . It is more common to see positive pressure in large buildings or houses equipped with swamp coolers .