Not all air filters are created equal. MERV stands for Minimum Efficiency Reporting Value, and it is a measure of a filter's ability to capture particles between 0.3 and 10 microns (µm). The higher the number, the better the filter is at trapping these particles in the air. However, filters with MERV ratings higher than 13 can restrict airflow due to their smaller pores, so it is important to choose the right filter for your HVAC system.
A MERV rating of 1 would be a basic window air conditioner unit, which is not designed to clean the air. Filters with higher MERV ratings should be changed more frequently (at least every three months) to avoid restricted airflow that can cause the system to operate inefficiently or even damage it. Oven filters with MERV ratings between 6 and 8 are the cheapest and are considered to be the minimum of efficiency. MERV 8 filters are effective at filtering contaminants such as pollen, dust mites, sawdust, mold spores, and lint from the air.
However, they don't do a proper job of filtering particles smaller than 10 microns, including mold spores, pet dander, and aerosols. To capture these particles, you will need a filter with a higher MERV rating. HEPA filters are the ultimate solution in the air filter world and far exceed what a MERV 13 can do. However, HEPA filter media is too thin to implement in existing HVAC systems and the only way to add one to an installation is through a standalone or portable HEPA air filtration system with its own dedicated fan designed to increase the resistance of this type of filter.
If you are looking for a high-quality oven filter that is not too expensive, a MERV 8-10 filter is worth considering. Oven and air filters above MERV 13 are typically found in a hospital environment, where air sanitation is of the utmost importance.