Asbestos

Certain kinds of asbestos (non-friable) are safe if left in place - you can research that more, but basically it's not a problem.

Where this is likely to be more of a problem is if you ever want to do any renovations. An asbestos test is required prior to filing for permits with the DOB, and if you have asbestos it's a whole extra layer of paperwork, specially licensed people to do the work, etc, etc - i.e., much extra expense and time.

I was going to buy a place that needed a lot of renovation work. I went back to see the place again with a contractor and the broker wore a mask to enter the apartment supposedly because the place was so dirty. The contractor told on the QT me the tile throughout the apartment was and old style used in the 50's and was asbestos. The contractor didn't look around too much because the tile was all broken up and crumbling. He said this was a serious asbestos abatement job. He said if the tile hadn't been broken, they probably could use a sealant/subfloor over the tile. We passed on the apartment.

Don't do asbestos or lead paint.

Don't buy anything built before 1970 then.

Everything built before 1970 has asbestos? No.