L.A.
We purchased one for our daughters room.
We used a Hunter Air machine..
You change out the filters about every 8 weeks.. Down here it is so dusty and pollen filled air, we at high times had to change it every 3 to 4 weeks. Made a huge difference.
We took down the drapes, got rid of the carpets and tried to keep her door closed when she was not home. We made it a sanctuary. so she could sleep at night. .