As a Sacramento homeowner, you likely view your health and the health of your family members as a priority. This means ensuring that the air quality in your home is safe for your family. Air quality has a direct influence on your wellness. It can impact your immune system, how you sleep, and specific respiratory and allergic reactions. HEPA (High-Efficiency Particulate Air) and MERV (Minimum Efficiency Reporting Values) are terms that can help you determine the quality of the filters you are using in your home.
What Is a HEPA Filter?
HEPA filters offer the most trusted technology for cleaning indoor air. Although most people have heard of HEPA filters, many don’t know much about them and how they work.
HEPA filters were first created for atomic energy clean rooms. The United States government, particularly the United States Department of Energy, designed HEPA filters to remove particulates as small as 0.3 µm. That is about 56 times thinner than a strand of human hair. Modern HEPA filters do an excellent job of capturing ultrafine particles that are much smaller than 0.3 µm.
The 0.3 µm reading describes what the HEPA filter will do when it is performing at its worst. When a HEPA filter works at full capacity, it can filter nearly 100% of the particles out of the air.
How Do HEPA Filters Work?
HEPA filters are built from a complicated mesh of thin synthetic fibers. These fibers have an electrostatic charge. This helps them to capture and trap particles in a type of mesh. The particles are attracted to the charge in a HEPA filter like metal strands are attracted to a magnet.
HEPA filters use four key mechanisms to attract the majority of harmful particles. The first is diffusion. This takes advantage of the Brownian motion phenomenon. Microscopic particles move in random and uncontrolled ways in a fluid or gas as they collide with other molecules. Because of this, as the particles zigzag around, they get trapped in the HEPA filter’s fiber web.
Another principle is an interception. When an airborne particle travels close to a HEPA fiber, the fiber snags it. The particle is trapped in the fiber and removed from the air.
Thanks to inertial impaction, big particles get stuck in a HEPA filter as they pass through it. Finally, electrostatic attraction means particles are attracted to the HEPA filter because of a special electric charge. The smaller the particle and the stronger the charge, the better it sticks to the filter.
How Effective Are HEPA Filters on Mold, Viruses, and Bacteria?
HEPA filters are extremely efficient at removing bacteria, viruses, and mold. High-quality HEPA filters can capture up to 99.9% of particles as small as 1 µm. This includes aerosolized particles. After around 72 hours, the trapped viruses will die or no longer be infectious. It is recommended that you not touch or clean a purifier filter if someone in the house is sick with a virus. Viruses that are trapped in the filter could still be infectious and could possibly spread.
What Is a Medical Grade HEPA Filter?
Medical grade HEPA filters are those that are used in a healthcare setting. This includes operating rooms and labs. Medical grade HEPA filters can capture up to 99.97% of airborne particles that are at least 3 µm or more. They offer superior protection against allergens that can trigger asthma and other small particulate pathogens that can wreak havoc when they enter the lungs.
There is a difference between a true HEPA filter and a HEPA-like or HEPA-style filter. If you are not using a true HEPA filter, it will not capture the same percentage of airborne particles as a genuine HEPA filter. Only a true HEPA filter can remove bacteria, viruses, and dangerous particulate pollution.
What Is An MERV Rating?
The MERV rating specifies a filter’s ability to remove larger particles between 0.3 and 10 µm. This rating is helpful when comparing the filters you buy. The rating system is based on testing methods used by the American Society of Heating, Refrigerating, and Air Conditioning Engineers (ASHRAE). The higher a filter’s MERV rating, the better it will do at removing certain particles from the air.
MERV ratings go from one to 20. A MERV rating of between one and four means that a filter can remove less than 20% of particles that are between three and 10 µm. A filter with a MERV rating of 12, by comparison, can remove up to 35% of particles between 1.0 and 0.3 µm while removing up to 90% of particles between 3.0 and 10 µm. A filter with a 16 MERV rating will remove up to 95% of particles between 0.3 and 1.0 µm.
A Practical Application of MERV Ratings
Seen from another angle, a filter with a MERV rating of between four and six will offer minimal filtration and is good for industrial workspaces or paint booth inlets. It will eliminate textile carpet fibers, pollen, debris, and dust mites.
Filters with a rating of between eight and 13 can be used to remove welding fumes, coal dust, and nebulizer dust. This category is the most recommended for both residential and commercial buildings.
Filters that are rated between 14 and 20 can get rid of viruses, smoke, carbon dust, microscopic allergens, bacteria, and auto fumes. These filters are typically used in hospital settings, smoky lounges, cleaning rooms, and spaces that have either radioactive or carcinogenic material.
MERV Versus HEPA Filters
Both MERV and HEPA filters remove airborne particles, but they do it in different ways.
A MERV 13 filter focuses on particles that are 0.3 µm or larger. HEPA filters attack particulates that are smaller than 0.3 µm. You will likely see a MERV filter in a commercial setting and HEPA filters in a hospital or medical setting. HEPA filters are more expensive but can be used in settings where MERV filters cannot be used.
More recently, home and business owners have become concerned about their filtration systems’ ability to trap viruses. The Centers for Disease Control and Prevention (CDC) recommends that homeowners or business owners concerned about this use an air purifier with a HEPA filter because of their ability to remove small particles. Many residential HVAC systems are not designed to support HEPA filters. For this reason, some homeowners have opted for a portable air purifier with a HEPA filter.
Working With HVAC Heroes in Sacramento
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