Standard filters work to keep your system and its ductwork clean, but they don't really improve indoor air quality. To do that with a filter you need a media filter.  The media filter rests between the main return duct and the blower cabinet and will improve dust and particle removal by seven times that of a standard filter.  Always choose a filter that matches your blower's capacity.  For optimum efficiency and filtration, Prillaman Mechanical recommends that you replace your disposable filters at least once a month. If you are concerned about air quality in your home, talk to your Prillaman professional about whole house air quality products.