system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How my neighbor's radon exhaust pipe is not a health concern for me.

My neighbors have a radon exhaust pipe that is pulling radon from beneath the slab of their home and exhausting it outside, about 15 feet from my home.  These pipes are estimated to exhaust at 2000 pCi/L when the EPA says there is "no safe level" but you should mitigate your home if it is greater than 4 pCi/L.  

Yes, the radon "dissipates" into the air but it has to go somewhere-- what's to stop it from coming in my windows and doors?  So it's constantly coming into my home at a low concentration?  No exposure is safe-- how is this not a threat to my health?
gpt
To dilute your neighbor's exhaust to safe levels, you need 500L of air for every L of exhaust.  If you have 5m between your houses, and your houses are 10m tall, and the pipe is 10cm (3") wide, then you have 5000L of air in the slice of air between your houses that's as wide as the pipe.  If you have a breeze of 10% the speed of the air flowing out the pipe, even ignoring that the atmosphere extends up much higher than the roof of your house, you are fine.

It would be much more important to run a radon test in your basement.  Radon is not a localized geologic problem.  If your neighbor has a problem, you probably have a problem as well.