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Will a HEPA Filter Prevent Mold Growth in the Home?

Will a HEPA Filter Prevent Mold Growth in the Home?

Are you thinking about getting an air purifier for your home or office? There's a lot to consider when purchasing a prospective machine. Reading through reviews and testimonials on the product is critical when conducting due diligence on your air remediation system.

Understanding the technology involved with these devices helps you choose the right machine for your specific application. The homeowner or business owner should also have a knowledge of air quality and the best machines to help remediate the air in particular situations.

In many cases, air purifiers can help remediate the air, improving air quality, but is it a good idea to get one of these machines for your home or office? Also, what are the limitations of HEPA filters, and do they remove mold spores from the air around the house?

Understanding Particulate Matter

The air environment outside of the home is a complex dynamic. It contains abundant levels of oxygen and other atmospheric gasses, along with other pollutants, toxins, microbes, pathogens, and particulate matter.

Particulate matter can enter the home due to natural events like wildfires or through the results of commerce and industry, such as exhaust fumes from a nearby highway or airport. It can also occur due to activities inside the home like burning incense or candles, or cooking,

There are several air pollutants and particulate matter causing concern for the health of homeowners living in areas with high exposure to particulate matter. Ozone, volatile organic compounds (VOCs), and mold are just a few of the issues with air quality facing homeowners.

All of these environmental toxins and particulate matter play a role in our health. We breathe them in every day, accumulating the presence of these substances in our bodies. As a result, many homeowners benefit from installing HEPA-based air filter systems in their homes to improve the air quality in their living space.

HEPA filters promise to remove over 99% of airborne particulate matter in the home. That means that you get a dramatic increase in the air quality in rooms, and an improvement in your health, sounds great, right?

This system is a great strategy to improve your overall health, but is the HEPA filter removing everything from the air? Is it possible for microorganisms and mold to pass through HEPA filters?

What Is a HEPA Air Filter?

A HEPA filter is a filtration system designed for scrubbing particulate matter from the air. We already discussed the particulate matter types, and the HEPA filter's inventors intended it for use in science to control particulate matter in radioactive experiments.

HEPA filters are now the gold standard in medical settings, and they're gaining popularity in home-based air-conditioning systems and commercial units as well. The HEPA filter is not a machine itself; it's a filter cartridge used in air remediation systems like air conditioners and HVACs.

 So, what is HEPA? What does it mean, and why should you install one of these filters in your home? More importantly, can a HEPA filter clean mold spores from infected rooms?

What Is the Meaning of HEPA?

First, let's start with the definition of HEPA. HEPA stands for High-Efficiency Particulate Air, and it's a description for filters capable of trapping more than 99.97% of all particulate matter in the air. However, the catch is that the filter only offers this level of efficacy in particulate matter measuring less than 0.3-microns in size.

0.3-microns is tiny, so small that you can't even see it with the naked eye. However, some pathogens are this size and even smaller. In 1983, regulators established the HEPA standards and guidelines for the industry. However, the invention of the HEPA technology goes all the way back to the Second World War.

The Manhattan Project sought to develop the first-ever nuclear weapon, and it succeeded, dropping the bombs on Hiroshima and Nagasaki to help with efforts to end the war.

During the research and development of the technology, scientists invented the first-ever HEPS filter, designed to capture any radioactive particles released during research and development on the atomic bomb.

So, why did these scientists decide on 0.3-microns as the standard for HEPA filters? This particle size is what's known in the scientific community as the "MPPS," or "most penetrating particle size." Science shows that this size is most optimal for collecting fine particulate matter.

How Do HEPA Air Purifying Filters Work?

The HEPA filter features design and construction with interlaced glass fiber twisted in different directions, creating a fibrous filter maze. As the particles travel through this web of interlaced fibers, they get caught and taken out of circulation through the following methods.


The air carries particles between two fibers. However, since the particle is larger than the gap, it remains behind in the HEPA fibers.

Direct Impaction

Larger contaminants like mold, dust, and pollen collide with fibers while moving through the filter, getting caught.


The airflow passes through the fibers without reducing pressure. However, the particulate matter remains behind, trapped in the HEPA fibers.


Smaller, ultra-fine particulate matter moves erratically compare to larger particles. As a result, they stick to fibers when passing through the filter.

Some devices have additional technology working alongside the HEPA filter, such as UV light traps, killing any other matter that manages to pass through the filter. These additional features also help remove fumes, smoke, VOCs, and other particles that pass through the main filter in the system.

What Is a "True HEPA" Filter?

If you browse through online listing for HEPA filters and devices, you'll notice the term "True HEPA" come up from time to time. So, what's the difference between True HEPA and HEPA, is the True HEPA filter any better with removing particulate matter from the air?

The reality is that the True HEPA moniker acts as a distinction between the American and European-made HEPA filters. Essentially it's a marketing term used to attract consumer's attention and create the difference between American-made and European-made products.

Europe has different HEPA standards and guidelines from the US. With the European filter versions, they must remove 85% of particulate matter instead of the 85% required by the European standard. Therefore, European HEPA filters are not "True HEPA' because they don't filter out all particulate matter.

With a European standard, there is a chance that pathogens like mold spores may make it out of the filter and keep circulating in the air. The US True HEPA certification is also known as the "HEPA-type" or "Ultra HEPA."

Do HEPA Filters Stop Mold?

As mentioned, if you want to stop mold in your home, you're going to need a True HEPA filter that removes 99.97% of all particulate matter from the air. However, you'll also need to purchase a new device working with air remediation technology.

You see, the traditional HVAC or air-conditioner system pushes the airflow over the HEPA filter. As a result, the process mechanically strains larger floating particulate matter from the air, storing it on the surface of the filter.

Therefore, the HEPA filter traps some particulate matter, but not all of it, even with a 99.97% Tue HEPA filter attached to your air conditioning device or HVAC. As a result, some bacteria and mold spores might circumvent the cleaning process, recirculating in your home.

It might also surprise the homeowner to learn that the HEPA filter might not be as effective as scientists think at removing VOCs from the air. This underestimation is because ultramicroscopic particle pollutants, like VOCs, can pass through the HEPA filter.

The EPA released a statement saying there are no standards on air quality and VOCs in the home. In addition, the standard air-cleaning devices adhere to was last updated in 2006. Therefore, no guarantee putting a HEPA or True HEPA filter in your air conditioner or HVAC system will capture and clean mold out of the air.

Homeowners need to be proactive and look for the signs of mold infestation, even if they have air remediation systems in their homes.

How Do I Know If I Have a Mold Infestation in My Home?

If you have a mold infestation in your home, you're likely to notice the change in air quality when it starts to get bad. The affected rooms around your home will develop a musty smell, and people who are living in those rooms might notice the appearance of allergic reactions to the mold spores they breathe.

However, by this stage, the mold is usually established and growing at a rapid pace. Therefore, it's important to catch the infestation as soon as possible. In addition, a regular air inspection of your home once a year ensures that every room is mold-free.

MI&T is the mold identification specialist. We utilize the latest technology to locate mold anywhere in your home. While we can't remove the mold, we can advise on the removal process. However, we're an independent company, and we don't contract with any mold removal business.

We're here to give you an independent evaluation of the air quality in your home. So contact us today and book your mold inspection with one of our friendly consultants.