Less expensive filters that have a MERV scale between 1-3 are usually constructed of disposable fiberglass. Around 1-inch thick, these filters are designed to prevent larger particles of dust, lint, and other debris from damaging your furnace. They do little to keep the indoor air clean.
Disposable, pleated furnace filters are the most popular option found in stores. These filters are made from polyester or cotton paper and will remove smaller particles like mold spores and dust mites. Because of their higher filtration rate, pleated filters should be changed frequently to avoid clogging and reducing airflow through the furnace. Pleated filters have a MERV rating of at least 6 and are more expensive than fiberglass filters.
The most effective air filters are disposable or permanent electrostatic air filters. With a MERV rating of 10 or higher, they are highly effective and are recommended in indoor environments for persons suffering from allergies or upper respiratory conditions.
Have questions about furnace air filters and indoor air quality? Call Maxwell Plumb, we're here to help.