The type of filter you should purchase will be dependent on your allergies, asthma, and other types of preexisting conditions. Most types of residential air filters include a MERV rating that is 12 or lower. Most people will not benefit from an air filter with a score that is higher than 12. On the other hand, hospitals and emergency centers should invest in air filters that feature a MERV classification of 16 or less. A hospital that performs surgeries should not invest in an air filter with a MERV score that is below 13.