curtains should be washed every 6 months. Dust, dirt, and other particles can accumulate on curtains and affect your indoor air quality. Washing your curtains regularly will help remove these pollutants and improve the air quality in your home.

It depends on how often they are exposed to dust and dirt. If they are only exposed to normal amounts of dust, then every 6-12 months should be fine. If they are exposed to a lot of dust, then every 3 months would be better.