world improvement proposal:

Invent elevators that can be safely used in case of fire, so that disabled people who can't use stairs can still safely get out of a building.

This would probably involve a backup power supply for the elevator and air filters on the elevator cabin.

Of course those elevators would be supposed to be ONLY used by disabled people in an evacuation (in regular service everyone can use them). For people who can use stairs, it's still better for them to use the stairs in an evacuation.
@J3317 @LunaDragofelis Good idea, biggest issue would be that elevators can use anywhere from 2% to 10% of a building's total electrical capacity. Plus, elevators use three-phase power to run the motors. The batteries, inverters, switchgear and supporting electronics would be large and expensive. But, evacuation of folks with disabilities is important. Many folks just wouldn't justify the cost, building owners will always skimp on costs where possible.