If we're going to throw out random theories for the cause like diet and pollution, what about all the volatile chemicals off-gassing from freshly manufactured goods?
I also have a couple different Austin Air purifier models. Also expensive but seems to work well.
But yeah, volatile chemicals are a form of hyper-local pollution. Perhaps less proof ATM, but close enough to regular (?) pollution to want to avoid it. Err to the side of caution, not to the side of cancer.
In short, radiation either has an immediate, very apparent and deadly effect, or a simple stochastic one that basically linearly increases with radiation exposure.