Science Buddies: "Ask an Expert"

I made the Radon detector and the instructions state what the basic reading should be on a multimeter for a cool room. Is there a chart to say what readings would be considered dangerous.... if say 15mV is a standard amount of alpha particles in a typical room, what reading would be considered dangerous?
The detector will be monitoring the radon levels in The Skywatcher Clan's Dragon Cave to ensure the members, and quests, who join the tribe's TERRANAUT CORPS exploration are not being exposed to dangerous levels of Radon.

Hi - The Ask an Expert forums are for students working on school science projects. If you used the project directions to build a radon detector, you may want to go back and reread the background tab for information about how it works and ranges. There are also links in the bibliography to help you start research for more information on this topic.
https://www.sciencebuddies.org/science- ... background

Amy
Science Buddies

I can not find the answer in the back ground or any other link. I am trying to find the designer himself to find the answer, but someone here must have built the device and made a chart of readings in relation to the professional detector (as suggested)...