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What is the efficiency percentage of HEPA filters in filtering particles greater than 0.3 microns in diameter?

  1. 99.99%

  2. 99.95%

  3. 99.97%

  4. 98.5%

The correct answer is: 99.97%

HEPA (High Efficiency Particulate Air) filters are specifically designed to capture very small airborne particles. The efficiency of HEPA filters is a critical factor in their performance and is defined by their ability to filter particles that are 0.3 microns in diameter, which is considered the most penetrating particle size. A HEPA filter must trap at least 99.97% of these particles to meet the HEPA standard. This high efficiency is achieved through a combination of mechanisms including interception, impaction, and diffusion, allowing the filter to capture not just the larger particles but also the smaller ones effectively. This specific efficiency level is crucial in environments where air quality is paramount, such as healthcare settings, laboratories, and environments that require controlled air quality. The other options present efficiency levels that fall short of the HEPA standard, which is why they are not correct. Therefore, knowing that HEPA filters effectively capture 99.97% of particles greater than 0.3 microns in diameter underscores their importance in maintaining a clean and safe environment.