Also, asbestos is all over the place in a lot of homes. Plus many locations also have Radon gas seeping in. These things are known about, but mostly ignored because of the cost to fix them.
Here in the UK if traces of asbestos are found the entire building is quarantined while a team of workers in hazchem suits and breathing apparatus removes it!
What's worse is that we've known about the dangers for more than 100 years.