Based in Manchester, Marie is one of the writers at HouseFresh and our resident dust expert. She works together with our in-house researchers and our Managing Editor to produce in-depth articles offering practical advice on how to tackle indoor air quality issues.
Our verdict:
If you want to improve the air quality in your home, then a HEPA filter is worth the investment. Various scientific studies show their effectiveness in removing mold spores and dust pollutants.
Eliminating such airborne contaminants can positively impact your health, especially if you suffer from allergies and/or asthma.
Of the three different HEPA filter types (classic, true and medical grade), be sure to go for either true or medical grade, as these are the most powerful.
Given that we spend so much of our lives at home, our air must be clean and fresh. This is even more important if you or anyone you live with suffers from allergies and/or asthma. Yet even daily cleaning can’t eliminate all the harmful airborne particles that build up repeatedly.
Running an air purifier is a great way to improve the air inside your home, but does it matter what kind of filter you use?
Short answer: yes, it does. HEPA filters are considered the best and most efficient form of filtration.
A good-quality air purifier with HEPA filtration can help remove these particles. This filter effectively reduces particulate matter (PM) found throughout our homes via dust, mold spores, pollen and pet dander.
According to the Environmental Protection Agency (EPA), HEPA filters can remove at least 99.97% of any airborne particles with a size of 0.3 microns. It may seem strange, but the smaller the particle, the more damage it could do to your health. The tiniest particles can penetrate your lungs more quickly and even enter your bloodstream.
While air purifiers are a highly effective way to utilize HEPA filtration, installing one in your HVAC system could be costly. The system may need to be fitted with new powerful equipment to work with the dense HEPA filter. MERV-13 filters are considered the least expensive option for your HVAC system.
| The Science Behind HEPA Filters Numerous scientific studies support that HEPA filters are worth the investment, especially regarding health issues. 📝 The American Academy of Pediatrics, for example, found that HEPA filters can reduce the concentrations of indoor PM, helping to ease asthma symptoms. The Academy also discovered that the filters may lower the concentration of toxic particulates in smoke. 📝 The EPA reports that various studies have found that HEPA filters may reduce allergy and asthma symptoms and benefit people with cardiovascular and respiratory health issues. 📝 Similarly, the NHS in the UK states that HEPA air purifiers can lower the risk of airborne pathogens being transmitted. While everyday life may have resumed following the devastating impact of the COVID-19 pandemic, the virus hasn’t completely gone away. Thankfully, many studies have found that HEPA filters may help stop the virus’s spread. 📝 The UK’s Manchester University reports that HEPA filters effectively reduce the transmission risk. 📝 Equally, the Centers for Disease Control and Prevention (CDC) states that when combined with mask-wearing, HEPA air purifiers can decrease exposure to the virus that causes COVID-19. |
How Does a HEPA Filter Work?
Now that you’re clued up about the benefits of HEPA filters let’s look at how they work to ensure the air inside your home is clean.
The filters contain dense pleated sheets sealed in a plastic or metal frame. Within these sheets is a tangle of randomly arranged fibers that create a sort of spider’s web to capture particles, including dust mites and mold spores.
A fan inside the purifier sucks in airborne pollutants, so the fibers can trap the contaminants. The device then recirculates clean, healthy air back into your home.
The are four ways that the particles are captured in HEPA filters:
- Diffusion — This stage occurs when very small particles (less than 0.1 microns) try to travel through the filter. Yet because the particles are so tiny, they diffuse through it instead. The particles eventually hit the fibers and become captured by them.
- Interception — Interception happens when larger particles (0.3 microns) run into the fibers, then collide and stick to them.
- Impaction — This occurs when bigger particles travel in a straight path directly into the filter. They then collide with the HEPA fibers and get trapped.
- Sieving — When the spaces between the fibers are too small for the largest particles to fit through, the particles are captured at the fibers, preventing them from moving further.
You can see how hard HEPA filters work to remove contaminants from your home, so you might also be wondering how long they last. Generally, the lifespan is around 6-12 months, but for a more in-depth look at why this is the case, check out our article here.
| 💡 Pro Tip: If you’re curious whether you can recycle the filters, our advice is… not really. That is unless you have a clean filter that is made from paper and synthetic fibers that you want to dispose of. Other than that, in most situations, you won’t be able to recycle your HEPA filter. |
Different Types of HEPA Filters
There isn’t just one type of HEPA filter you can use in your purifier but three: classic, true, and medical-grade. They’re all effective, yet some have more powerful capabilities than others.
Each HEPA filter is graded from H8 to H14; the higher the grade, the more effective it will be at removing particles.
Let’s start with the most basic:
| Classic HEPA | These filters are good for improving your everyday air quality and useful if you’ve only got a small space to purify. They can eliminate 99% of airborne particles as small as 2 microns (including pollen, animal dander, and dust). 🤓 The classic filter is graded H8 to H10. |
| True HEPA | This is the most widespread type and is commonly used in the home as it can remove various harmful pollutants such as mold, pet dander, fine dust and smoke. The true model tops the classic filter because it can capture 99.97% of particles as small as 0.3 microns, which is the most penetrating particle size (MPPS). To be labeled “true,” the filters are rigorously tested and certified by organizations such as AHAM (Association of Home Appliance Manufacturers) and ASHRAE (American Society of Heating, Refrigerating, and Air Conditioning Engineers). 🤓 These filters are categorized as H11 and H12. |
| Medical-Grade HEPA | The most powerful of all, medical-grade HEPA filters are used in places where breathing clean, healthy air is vital, such as hospitals and clinics. These filters are also used in electronics manufacturing, for example, during the production of LCD screens. They can remove up to 99.995% of particles as small as 0.1 microns, including asbestos, anthrax, insecticides, viruses and wildfire smoke. Medical-grade filters can also eliminate contaminants typically found in the home, like dust, pet dander, pollen, and mold. Like with true HEPA filters, medical-grade filters are also tested in a controlled environment before receiving certification. 🤓 Medical-grade HEPA filters are categorized as H13 and H14. |
A word of advice: be aware that some filters are marketed as “HEPA-Like.” This means they haven’t undergone testing procedures to ensure they perform to the required standard, so it’s best to steer clear and choose one of the above.
Conclusion
HEPA filtration is a worthwhile investment if you want to improve the air quality in your home. This is especially so if you have health concerns, as HEPA filters are super effective at eliminating the fine airborne particles that can worsen conditions such as allergies and asthma.
It’s wise to go for a true HEPA filter, as these can remove at least 99.97% of any airborne particles as small as 0.3 microns. Yet a medical-grade HEPA filter will eradicate 99.995% of particles as tiny as 0.1 microns for even more powerful filtration.