Previously painted (before 1980) door and frames are old and have lead-based paint. Clean up lead dust for the children! The door rubbing against the frame will create dust. This area is called a friction point. Friction points are also on windows. Lead dust is dangerous to children under 7, and not good for the rest of us, either.
You can clean up lead paint dust for children with a daily Swiffer-type mop under all old doors (including frames) and widows.
Children will chew on wood painted with lead-based paint because lead tastes sweet.
San Francisco has many old buildings. It’s critical that if you think you may have lead dust and your children, especially under 7, that you use the Swiffer mop method to clean daily where the dust from the friction points on doors and windows with wooden frames falls.
Also, lead-based paint can be found outside on porches and decks.
Painting over lead-based paint with paint made today, will not completely fix the problem.
There are other types of paints, usually referred to as encapsulants, that will eventually flake or rub off at friction points, and then you have the same problem; though maybe a bit less. EPA wants o% lead-based paint dust in homes with children. Realistically, let’s all work together to do what is possible and clean up the rest.