I've been in the same place for almost 4 years now and I've been asking the landlord to clean the ducts because the dust is getting really bad in my basement suite. She says that the filters just need to be changed every 3 months and that there is no dust in the vents....how can i prove that there is dust in the vents? Its obvious that there is dust on my vents throughout but she still won't clean it....how do I convince her that it needs to be cleaned.