Many brands have adopted their own proprietary rating system that can lead to a lot of confusion. Instead, the US Department of Energy rates filter efficiency using the MERV (Minimum Efficiency Reporting Value) rating system. This standardized system measures how effectively a filter removes particles as air passes through an air filter. While you can choose to use a filter with a MERV rating as high as you want, it is worth noting that filters with higher MERV ratings can reduce airflow, which may lead to problems. A filter is an excellent choice for general residential air filtration; they are affordable, do not overly reduce air flow, and can provide above average air filtration in your home.