What if there are no windows and back doors?

You mean what if the house has no windows or back doors? The following methods can be considered:

1. Contact the local government or property management company to find out whether the house can be added with windows or back doors.

2. If you can't add windows or back doors, you can consider installing a ventilation system to improve indoor air quality.

If the above methods are not feasible, you can consider moving to other places with better housing conditions.