First, replace your AC filters on a regular basis, or get an air conditioning service plan that includes a filter change – especially if you have allergies or live in a polluted metropolitan area. Examine your air ducts as well. Dust, dander and even mold can collect in your ducts over time, lowering overall air quality. Hire an expert to ensure that your ducts are flowing clean, fresh air. Also, control the humidity in the home. Mold and mildew thrive in humid and damp environments, causing respiratory disorders such as allergies and asthma. With a few strategically positioned dehumidifiers, you can reduce the moisture in the air and prevent the formation of bothersome molds.