radon in attached houses 6

https://tango-wiki.win/index.php/Your_Local_York_PA_Radon_Guide:_Testing,_Mitigation,_and_What_Every_Homeowner_Should_Know

Radon in attached houses can be tricky because it seeps in through shared walls and foundations, not just the ground floor. If your neighbor's place has high levels, yours might too, especially if there's a common basement or crawl space. Testing both units is smart, as radon moves easily between connected structures, and mitigation might need a joint approach.