Chances are good, if you’ve done any research or shopped for an air purifier, you’ve encountered the term HEPA in reference to the filters. Most air purifiers use HEPA technology in their filter system because it has been proven to be the most effective tool in cleaning impurities out of the air.

What is a HEPA Filter for Air Purifiers and How Does it Work?

HEPA stands for high efficiency particulate air. The pleated, mechanical filter forces the air through a web of fine mesh. Several types of harmful particles like pollen, dust, and pet dander are then trapped in the filter and clean, purified air is pushed back out.

In order for a HEPA filter to be called a HEPA filter, it has to be tested, approved and meet U.S. government standards. The filter must trap 99.97 percent of airborne particles that are 0.3 microns or larger. Microns are one-millionth of a meter and are how particles are measured. To give you some perspective, humans can’t see anything smaller than 10 microns – so, as you might imagine, 0.3 is super tiny.

When and Why Were HEPA Filters Invented?

We hear a lot about HEPA filters these days, especially with the emergence of the COVID-19 pandemic in 2020. But the technology has actually been around since the early 1940s. HEPA filter technology was created during the Manhattan Project which was a classified research and development program in the U.S. with the purpose of making nuclear weapons during World War II.

Scientists working on the project at the time realized they needed to contain the spread of radioactive contaminants in the air to protect themselves and others so, they developed the HEPA filter technology to filter it out of the air. The filters were introduced for commercial use in the 50s to eliminate pollen, smoke, viruses, bacteria, and other airborne contaminants in hospitals and other large workplace settings. The popularity of HEPA filters has grown through the years as we continue to learn about the negative impacts of air pollution and the importance of clean air.

What Other Types of Filters are Used with HEPA Filters in Air Purifiers?

An air purifier with only a HEPA filter is pretty effective in purifying the air you breathe in your home. They’re designed to remove the most common contaminants in the air. HEPA filters can last anywhere between six and twelve months, after that, they will need to be replaced. Some purifiers have permanent or washable HEPA filters – permanent filters can be regularly vacuumed and washable ones can be washed in cold water to clean them. And while HEPA filters can help pull dust, pollen, pet dander, and a host of other airborne irritants out of the air, they will not rid your home of gases, smoke, or odors.

Many air purifiers will have what’s called a pre-filter that’s designed to trap large particles and then the smaller pollutants are caught in the main HEPA filter. Some purifiers will also have other filters to help with the air purification process. HEPA filters can work in combination with several others to address your specific needs and allergy triggers.

• Activated Carbon Filters
  Activated carbon won’t get rid of airborne particles, but it is really effective in pulling odors out of the air inside your home. They work by absorbing the odor and generally have to be replaced every three months.
• Ionizers
  Ionizers create a static charge that airborne pollutants will stick to and then fall on the nearest surface so they can be eventually cleaned up. Ionizers have been shown to kill viruses.
• Ozone Generators
  Air purifiers with ozone generators alter the chemical composition of pollutants and can make your home smell better. But ozone is unsafe and you should steer clear of any air purifier that generates it.
• Ultraviolet Light/Ultraviolet Germicidal Irradiation (UVGI)
  Some air purifiers come equipped with UV lamps which claim to kill viruses, bacteria and fungal spores in the air. It’s important to note the UV light has to be very powerful and the exposure must last several minutes to several hours to work correctly.

Air purifiers can be a significant investment ranging anywhere from 100 dollars to a thousand, depending on the make and model you choose. So, you want to make sure you’re getting the best one for your family and your particular circumstances.

If your choices come down to cost, be sure to choose an air purifier with a HEPA filter. But don’t be fooled by clever or misleading wording on the package. When shopping for an air purifier – make sure the one you choose has a true HEPA filter. Look for words on the box like “true HEPA” or “U.S. HEPA standards.” Steer clear of products described as “HEPA-like” or “HEPA style” – they won’t meet the standards you need or want.

FAQs

1. What is a HEPA filter? A HEPA (High Efficiency Particulate Air) filter is a pleated mechanical filter that traps airborne particles as air passes through it. To be classified as a true HEPA filter, it must capture at least 99.97% of particles that are 0.3 microns or larger.

2. How does a HEPA filter work? HEPA filters work by forcing air through a fine mesh that traps harmful particles like pollen, dust, and pet dander. Clean, purified air is then released back into the room.

3. Why was the HEPA filter invented? HEPA filters were originally developed during the Manhattan Project in the 1940s to contain radioactive contaminants. The technology was later adapted for commercial use in hospitals and other settings to filter out airborne contaminants like pollen, smoke, and bacteria.

4. What particles can a HEPA filter remove? HEPA filters are effective at removing small particles like pollen, dust, pet dander, and other allergens. They can capture particles as small as 0.3 microns, which is far smaller than what the human eye can see.

5. How long do HEPA filters last? HEPA filters typically last between 6 to 12 months, depending on the air quality and usage. After this period, they should be replaced. Some models have washable or permanent HEPA filters that can be cleaned rather than replaced.

6. Do HEPA filters remove odors or gases? No, HEPA filters are not effective at removing gases, smoke, or odors. They are designed to capture particulate matter, not airborne chemicals or smells.

7. What additional filters are used with HEPA filters? Many air purifiers use additional filters alongside HEPA filters to enhance air purification:

• Pre-filters: Trap large particles before the air reaches the HEPA filter.
• Activated Carbon Filters: Absorb odors and gases, typically needing replacement every 3 months.
• Ionizers: Charge particles so they stick to nearby surfaces, and can help kill viruses.
• Ozone Generators: Alter pollutants’ chemical composition, but produce unsafe ozone and should be avoided.
• UV Lights: Kill viruses, bacteria, and fungal spores, though they require powerful UV lamps and prolonged exposure to be effective.

8. How do I know if an air purifier has a true HEPA filter? When shopping for an air purifier, ensure the product is labeled as “true HEPA” or “U.S. HEPA standards” to guarantee it meets the required filtration standards. Avoid products labeled “HEPA-like” or “HEPA style” as they do not meet the same filtration efficiency.

9. Are HEPA filters effective for allergies? Yes, HEPA filters are highly effective in reducing allergens like dust, pollen, and pet dander, making them a great option for people with allergies or sensitivities to airborne particles.

10. Are HEPA filters safe to use? Yes, HEPA filters are completely safe. They do not emit harmful substances and effectively improve indoor air quality by trapping airborne pollutants.