If you have a newer furnace, it probably has a filter. To check, open the door to the furnace and look for a metal grille. The filter is usually located behind this grille. If you don’t see a grille or can’t find the filter, consult your furnace’s owner’s manual.
Filters help remove these particles from the air, making it easier to breathe and reducing wear on your furnace. Installing a filter is easy. Simply measure the opening of your furnace and purchase a filter that is the same size or slightly smaller. Most filters fit into a metal frame that snaps into place behind the grille.