Indoor air quality is a growing concern as inhalation of particulate matter has been linked to asthma, lung cancer, cardiovascular problems and even early death. Air filters and air cleaning equipment are designed to remove particles, also called particulates, from the air. Particulates refer to tiny particles suspended in the air. As a general rule, the smaller the particle, the longer it stays in the air.
MERV is the minimum efficiency reporting value. This is the rating based on efficiently of air filters to remove particles of various sizes at different airflow rates. MERV ratings range from 1 - 16 and measurements are in microns. Higher MERV ratings mean fewer dust particles and other airborne contaminants pass through the filter. Some of the common particles related to MERV ratings are pet dander, insecticide dust, smog, dust, viruses, wood, tobacco smoke, spores, bacteria and pollen.
A micron is a micrometer, a measurement unit equivalent to one millionth of a meter. For example, a human hair is about 100 microns wide whereas dust particles and red blood cells are about 7 microns in diameter.
HEPA stands fro high-efficiency particulate air filter. This type of filter is designed to remove a minimum of 99.97% of air particles 0.3 microns in size.