Gas Monitor on Amazon Not sure if Amazon links are allowed here, if not then just search for "Gas Monitor".

Yes, you can use detectors for gas just like smoke/fire. Since you're in a condo you could offer to pay for your neighbors to have them installed as well, kinda depends on how cool they would be with that.

I have an irrational fear of heights. So I don't go near railings/balconies, etc. on tall buildings. I don't need therapy to help me get over that issue. Long term, if this continues to be a problem for you then consider to moving to a single-family detached structure without gas service - and not near any fuel/gas depots.