That was the point of my mention of a water sprinkler. You note that it is releasing SOME particles into the atmosphere. So? It always does above and beyond the background radiation. Now it's releasing more. How much is too much?
If you would turn on your Geiger counter you'd hear clicks from ionizations happening all the time around you. How much faster would it click in Osaka? In Odessa?
If you can't characterize the release, or the area of effect, then you might as well be warning about a potential meteorite strike.
Enough said.......