Which statement about MERV ratings is correct?

• A. The higher the MERV number, the larger the particle it removes
• B. The higher the MERV number, the smaller the particle it removes
• C. MERV rating is irrelevant to particle size
• D. MERV is only for filtration rate

Answer: (B)

Understanding MERV ratings starts with how filters perform across particle sizes. The MERV number represents filtration efficiency for different-sized particles. As the rating increases, the filter becomes better at capturing smaller particles, so it’s correct to say that higher MERV numbers correspond to removing finer particulates. This doesn’t imply it can’t remove larger particles as well, but the main trend is improved capture of smaller particles with higher ratings. It’s also worth noting that higher efficiency can come with more airflow resistance, so practical system considerations matter.