I'm not a radon remediator—I'll just put that out there—but one thing we're grappling with is that even with the new building stock, the building code does not have a requirement to test the home before people occupy it. In part that's because as you're building a home it's open to the air. Having a point at which the house is tested before an occupant enters is an important piece that's still being sorted out.
After the home is built to code, we still need to make sure it really is radon-resistant. Research in B.C. has found that in some cases the newer homes actually were higher than they had expected to begin with, so changes have been made and recommendations made in B.C. to fix that. But the building code is new, and it will go through growing pains. Understanding how effective it actually is will take a little bit more time.