What is the efficiency of a HEPA filter?

A HEPA filter, which stands for High-Efficiency Particulate Air filter, is designed to capture a significant percentage of particles in the air, specifically those that are 0.3 microns in diameter. The classification of HEPA filters requires them to filter out at least 99.97% of these particulate contaminants from the air that passes through them. This remarkable efficiency makes HEPA filters an essential component in environments where air quality and safety are critical, such as in asbestos handling, medical facilities, and clean rooms.

This high efficiency ensures that even the smallest particles, which can include dust, pollen, and more dangerous contaminants like asbestos fibers, are effectively trapped. Therefore, the 99.97% efficiency rating is key to protecting workers and the environment from harmful exposures, making it the correct answer to the question regarding the efficiency of a HEPA filter.