radon vent pipe 2

https://getwestcountyradontoday.juniperbrief.com/posts/understanding-west-county-radon-what-homeowners-need-to-know

A radon vent pipe pokes through the roof of a house, looking like a small white stovepipe. It's part of a system that sucks soil gas from beneath the foundation and safely releases it into the open air. Builders install them during new construction or retrofit them with a fan to reduce cancer risk from radioactive radon buildup. The pipe needs to extend at least ten inches above the roofline so the gas doesn't re-enter through windows.