HEPA filters & UV disinfection systems – promises & reality

Air disinfectants have always been vital to protecting us against viruses in hospitals and other medical settings. Since the onset of the COVID-19 pandemic, air disinfection systems have taken on a new level of importance. They’ve become the most effective way of ensuring our health and safety - not just in hospitals but in our homes, offices, and other enclosed public places.

However, it’s important to understand the differences between the various air cleaning devices available, from HEPA air filters to air disinfectants. This is because not all air cleaners disinfect the air and protect against viruses and bacteria.

 What is a HEPA Filter?

A HEPA filter is a non-woven material that traps dust particles and larger microorganisms. It works in a similar way to a medical face mask. The downfall of a HEPA filter is that although microorganisms become trapped, they continue to thrive and multiply, and can even be re-released into the air in greater quantities than before.

It’s worth noting that this activity doesn’t depend on the HEPA filter itself but on the temperature and humidity of the surrounding environment. Certain environmental conditions are favorable to the reproduction and subsequent spread of microorganisms.

Mold on the Fibers of a HEPA Filter (Photo by CDC)

HEPA filters only protect against dust and allergies but are sometimes marketed as being bactericidal. Expensive HEPA filter machines can even pollute the air and they do not protect against viruses and bacteria. By contrast, relatively inexpensive UV air disinfection systems (such as ozonation systems, plasma air purifiers, and bactericidal recirculation systems) are guaranteed to disinfect the air around you.

Here’s how science explains it:

• HEPA filters can only trap particles over 0.3 microns in size
• Most viruses are 0.01 to 0.5 microns in size
• The SARS-CoV-2 (COVID-19) virus is 0.1 to 0.125 microns

 This shows that the particles causing the COVID-19 virus (and other viruses) are too small to be trapped by a HEPA filter; they simply pass through.

 Are HEPA Filters Useful?

HEPA filters are essential for cleaning the air we breathe – particularly in cities, where pollution levels are often higher than in other areas. According to MIT studies, air pollution in the United States kills around 200,000 people every year. Additionally, there are serious diseases that can develop due to seasonal allergies, dust allergies, and mold allergies. There is ample research to show the role of dust particles in the development of degenerative brain disorders, such as Alzheimer’s and Parkinson’s.

These studies highlight the importance of air purifiers to our health. To keep the air biologically safe, however, we recommend using them alongside air disinfectants. An air disinfection device will kill viruses and bacteria; an air purifier will then filter them out.

How do You Choose a HEPA Filter?

HEPA filters have various filtration classes, the most common and affordable of which is the E10. Here’s how the different classes compare:

•           E10: Has a particle capture efficiency of only 85%
•           E11: Has a particle capture efficiency of 95%
•           E12: Has a particle capture efficiency of 5%
•           H13: Has a particle capture efficiency of 95% - a true HEPA filter

Filters of classes E10-E12 are not strictly HEPA filters, but EPA filters. Unfortunately, the standards of different countries allow manufacturers to play on the names, which can mislead consumers. However, if you choose a HEPA filter of E12 or above, you will have sufficient protection against dust. The HEPA air purifiers we offer on our website are H13, which provide the ultimate in protection.

Ultraviolet Radiation and Air Disinfectants

If you’re looking to tackle viruses and bacteria (instead of, or as well as dust), a UV air disinfection device is the way to go. Disinfecting with ultraviolet radiation is medically proven to destroy pathogens and disinfect the air.

Ultraviolet (UV) rays are defined as electromagnetic radiation in the optical (visible) spectrum. They have a wavelength range of 100-400 nm. Since this spectrum is visible to the human eye, we can see that UV lamps emit a white-violet glow.

There are several UV air disinfection devices available to consumers. In basic terms, they’re composed of a case with a built-in fan and an ultraviolet lamp. Simpler and less effective models don’t have directed airflow or zoning capabilities. The air disinfection devices that we offer do; they have powerful directed airflow and a unique method for dividing and/or zoning rooms.

How do UV Air Disinfection Devices Work? How Does UV Light Kill Viruses?

Only UV radiation with a wavelength of 205-315 nm can destroy viruses and bacteria. Radiation in this spectrum damages the DNA of a microorganism’s cell nucleus. In scientific terms, UV radiation inflicts destructively modifying damage to the RNA and DNA of the cell.

In the case of multicellular organisms, such damage causes gradually accumulating changes. Over time, the cells are unable to divide and multiply. This leads to the extinction of the first and subsequent generations of the organisms.

Destruction of gene material by ultraviolet radiation (Photo by National Cancer Institute)

Different types of microorganisms are susceptible to different ranges of the ultraviolet spectrum. The larger the virus, the more susceptible it is. This list shows various microorganisms in order of their sensitivity to UV light, from the most sensitive to the least:

• Bacteria
• Fungi
• Yeast
• Bacterial spores
• Viruses

 Out of all the above microorganisms, large herpes viruses and coronaviruses are the most susceptible, owing to their size, which ranges from 0.1 to 0.2 microns.

The size of the SARS-CoV-2 virus (coronovirus), together with the viral envelope, reaches 0.1-0.2 microns. (Photo by Fusion Medical Animation)

UV light is not a complete cure, however. Some viruses are immune to ultraviolet radiation. These include the RNA-containing virus, IPNV, of the genus Aquabirnavirus; and AHNV of the genus Nodaviridae. This immunity is due to these viruses’ extremely small size (diameters of 0.06 and 0.03 microns respectively).

 

Air Purifiers vs Air Disinfectants: What’s the Difference?

If you want to rid the air of dust particles, choose a HEPA filter air purifier.

If you want to disinfect the air and protect against viruses and bacteria, choose an air disinfection device.

For completely pure, healthy air, choose both; the combination of technologies will give you the highest degree of air cleaning and disinfection.

Can HEPA Filters be Installed in an Air Disinfection Device?

We’ve received countless requests to install HEPA filters in our air disinfection devices. We do offer a free-standing machine that has this option. However, we must point out that among the important operational features of an air disinfection device is the speed at which it disinfects the air.

Since we live in ventilated buildings, not hermetically-sealed spaces, any air disinfection device needs time to disinfect the air before we inhale it. An air recirculation system’s disinfecting block has to process the room’s entire volume of air roughly 2-3 times an hour. In a room size of 66 ft² with a height of 9ft, the recommended safe air performance should be at least 330ft³/hour. This shows how unsuitable it would be to have an integrated HEPA filter with an air resistance reaching 600 Pa.

Integrating a HEPA filter can significantly reduce an air disinfectant’s airflow speed (especially when the filter gets dirty over time). This prevents the disinfection process from working optimally. A poorly-working device not only means you’ve wasted your money but also means you’re endangering your health.

Our Expert Recommendation

If you want pure, clean, healthy air, we recommend installing an air purifier/HEPA filter and an air disinfectant separately. This will allow the two devices to work independently for the highest level of efficiency, reliability, and air safety. Your air will be free of allergy-causing dust particles and the viruses and bacteria that pose a hazard to your health.

© Oleg Osadchuk
22/10/2020

Featured image by Liquid (Artiste) Arya on Unsplash