#ACTUAL SIZE FOR 4 INCH AIR FILTER PLUS#

An NIH literature review indicates that filters in this range can significantly reduce indoor fine-particulate pollution and alleviate some respiratory ailments. This MERV range, Owen said, “covers most of the stuff that people are likely to breathe in unless they’re really close to the source.” The EPA says filters rated MERV 7 to 13 “are likely to be nearly as effective as true HEPA filters at controlling most airborne indoor particles.” The higher end of the range, MERV 11 to 13, removes 20-plus to 50-plus percent of the very smallest, 0.3-to-1.0-micron particulates, and filters in this range are especially popular.

#ACTUAL SIZE FOR 4 INCH AIR FILTER PLUS#

(For more detail on these models, see the A perfectly good HVAC filter and Two other filters that are also fine sections.) We focused on filters in the MERV 8 to 13 range because they are good to excellent at removing fine particulates (as small as 0.3 to 3.0 microns in diameter, including smoke and exhaust particles and bacteria), plus anything larger.

MERV 8 to 13: This is the category we’d recommend for people who care about indoor air quality, and there are many equally good examples, such as the Nordic Pure MERV 10 and MERV 12, the Honeywell FPR 9, and the Filtrete 1500.

If you are reading this guide, you probably care too much about air quality to consider one of these filters, but if you’re living (or vacationing) in a rental and don’t want to invest much-especially if the existing filter is problematically old or dirty-replacing it with a MERV 1 to 4 filter would be a fine quick fix. “Think of how important your screen door is in summer when there’s flies out,” Owen said. They prolong the life of your equipment and help keep it running efficiently in the heating and cooling seasons. But even with their limitations, these filters aren’t pointless. They have little to no impact on fine particulates like pollen and smoke, so they will not do much to ease respiratory issues.

Their purpose is to keep particles larger than 10 microns-including pet hair (but not dander), carpet fibers, and heavy dust-from clogging the heating/cooling coils and ducts in your HVAC system.

MERV 1 to 4 (and unrated): Filters like the MERV 4 E-Z Flow, MERV 2 True Blue, MERV 1 Filtrete Basic Cut-To-Fit, and the unrated Flanders, are the cheapest (some under $1 apiece) and most basic MERV-rated filters.If it is, there are several examples of qualified filters that we’d recommend-including the Nordic Pure MERV 12, a perfectly good filter that we’d look for first (because it often costs less), as well as two other filters that are also fine. But those are rare circumstances, and the decision to pay more for a better filter or not mainly comes down to whether or not cleaner air is a priority for you. Second, they can put stress on some HVAC equipment, making the system less effective at heating and cooling, potentially even shortening its lifespan by restricting airflow and forcing the equipment to run harder. You’re supposed to replace filters every few months, so the cost adds up. However, these filters have a few drawbacks-first, they usually cost significantly more than basic fiberglass filters. Compared with the cheapest basic filters available, medium-efficiency MERV filters like the Nordic Pure MERV 12 can greatly reduce airborne dust, mold spores, pollen, and even smoke, and doing that can help ease respiratory ailments, according to an NIH review.

Actual size for 4 inch air filter