COVID-19: Can your home’s HVAC system protect you?


Misinformation is rampant. Here’s the truth—as far as we know now.

I wanted to write this post because clients keep asking—especially over the past two weeks—what they can do to keep their families safe at home from the novel coronavirus COVID-19. And that makes sense. We’re an HVAC and plumbing company dedicated to home comfort and healthfulness.

But what’s important to recognize is the rampant misinformation out there designed to capitalize on people’s fears. I want to dispel some of it, and offer practical advice based on what we know so far.

Arm yourself with credible information.

I first want to make clear: the most important thing you can do is stay updated with credible information. Right now, scientists and medical professionals around the world are working to better understand and develop treatments for this new coronavirus. But it’s still very early, despite its rapid—and unnerving—spread. It’s crucial to acknowledge what we don’t know, and to make evidence-based decisions with what we do know.

This quickly evolving situation is made even more challenging by the alarming amount of misinformation out there. Faced with a global pandemic, we must all arm ourselves with credible information from reliable sources. Two such sources are:

Centers for Disease Control & Prevention (CDC)

World Health Organization (WHO)

Knowing what you don’t know is vital. And outside of these two sources, we must all be wary of scams. They run rampant. Unscrupulous individuals are trying to take advantage of and capitalize on our fears. No matter how legitimate a claim seems, always vet it for truthfulness. You can do this fairly easily.

Simply copy the headline or a portion of the claim, surround it with quotation marks, and run a Google search. Here’s an example with a fake tip that circulated via Facebook, Twitter and email, purportedly from Stanford University: “take a few sips of water every 15 minutes at least.”

After running that search, it will be clear to you the information is neither true nor from Stanford.

Can your HVAC system help?

Maybe. As far as we know, only to a small degree right now. And perhaps not at all. If you hear something different, vet it. And vet me and this post for accuracy! I want to emphasize I’m neither a scientist nor an expert on this virus. That’s how serious I am about preventing the spread of misinformation, which will only increase the spread of the virus.

Air Filters

You should replace your HVAC system’s air filters regularly. High-end pleated filters can last as long as six months, while less expensive fiberglass filters should be replaced every 30 days or so. They will keep your home freer from airborne contaminants and particulate matter. But they will not kill or capture COVID-19.


Most residential HVAC system air filters carry MERV ratings. High-end filtration systems, such as in hospitals and many standalone air purifiers carry HEPA ratings. You might read that HEPA filters can prevent the spread of COVID-19.

A MERV rated filter with a value of 13–16 (a high rating) can remove up to 75% of airborne contaminants 0.3 microns or greater. A HEPA filter brings that percentage up to 99.7%. You can buy HEPA filters for your HVAC system. But they are less efficient, and still likely offer little protection against COVID-19 and other viruses, which are many times smaller than 0.3 microns. Moreover, the jury is still out whether this virus is airborne. As of this writing, scientists believe COVID-19 is spread through droplets, and not yet airborne. This information—and the virus’ transmission—could, of course, change.

A recent study (which has yet to be peer-reviewed as of this writing) from researchers at Princeton University, the University of California, Los Angeles and the National Institutes of Health has shown that airborne transmission is “plausible.” While that would be terrible news, it could be a situation in which certain highly specialized air filters help. But even then, they won’t kill the virus. They’ll only contain it while it lives on for days.

Don’t be duped into believing a residential HVAC air filter is up to the task of trapping or killing COVID-19. It’s not.

Ultraviolet Light Whole-Home Purifiers

More now than ever, clients are asking me about ultraviolet light whole-home air purifiers. These devices are also commonly known as blue light or simply UV filters. To be clear, these are not “filters” in the traditional sense, but rather ultraviolet lights installed in your home’s HVAC ducts. The light they shine—called UVC—is from a portion of the ultraviolet spectrum with wavelengths ranging from 200 to 280 nm.

These devices are typically marketed as being able to “kill up to 99% of existing mold, mildew, and airborne viruses.” I recommend them to most of our clients because they can keep you and your family healthier at home.

Blue light filters are relatively inexpensive, fairly simple to install, and do kill viruses. But, again, COVID-19 has not shown to be airborne. What’s more, even were it to become airborne, we don’t know how long the virus would need to be exposed to UV light before it dies or mutates enough to prevent its spread.

Regarding its application to COVID-19, this is a technology we’ll need to stay tuned for more information on. That said, you can pick one up on Amazon and, based on the unit, have it professionally installed starting at around $400 (including the cost of the unit).

So, what should you do to keep your household safe?

You should listen to and follow the advice given by government officials, and real scientists and medical professionals. Much of the advice that follows you’ll have heard by now. But it’s worth repeating.

  1. Educate yourself, friends, and loved ones about COVID-19 symptoms.
  2. Know when to see a doctor, which is as soon as you experience symptoms (they tend to be flu-like).
  3. Understand risk factors, which include travel to or from areas and residences suffering an ongoing spread of the virus.
  4. Practice “social distancing” in public spaces. It’s ok and not at all offensive to refuse to shake hands during a pandemic like this one.
  5. Stay home from work and school and away from public areas if you’re sick.
  6. Wash your hands with soap and water often, counting to at least 20 seconds (you’ll probably want to keep hand lotion around as the washing will dry out your skin).
  7. Use an alcohol-based hand sanitizer when you’re unable to wash your hands.
  8. Always cover your mouth and nose when you cough or sneeze. And don’t cover your face with your hand. Use a tissue or the inside of your elbow.
  9. Avoid touching your face if your hands aren’t clean. It’s hard to do but becomes easier if you start pretending your hands are never clean.
  10. If someone is or seems sick, avoid close contact.
  11. If you’re sick or maybe sick, don’t share dishes, glasses, bedding, or other household items.
  12. Clean and disinfect the surfaces you touch often. Suitable cleaners for non-porous surfaces include solutions made from at 70% alcohol, diluted bleach and most common household disinfectants registered by the EPA.To prepare a bleach solution, the CDC recommends:
    1. 5 tablespoons (1/3 cup) bleach per gallon of water or
    2. 4 teaspoons bleach per quart of water

Is that all?

Yes. At Donnelly’s, we’re dedicated to your home comfort and healthfulness. But we’re not scientists or medical professionals. We’re here to share what we know about COVID-19 so you, your friends, and loved ones can stay safe.

In a rapidly evolving situation like this, we do what we can: bring you sensibly, truthful advice. As a local, family-owned business, we feel it’s our responsibility to our community. Only by working together can we do our parts in limiting the spread of this virus.

We’re all in this together. And together, we’ll make it through.

Need service? 

Even during a time like this, you can count on the Donnelly’s team of Home Comfort Specialists. We’re available to help you in your times of need. Fill out the form below to schedule a Donnelly’s visit and rest assured we are taking every precaution available to prevent the spread of any illness. You can see our safety policy here.


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