Improve Indoor Air Quality with UV Light to Fight COVID and Flu!

Masks are a thing of the past for most Americans. Even though a lot of people are still catching and spreading COVID these days, masking has pretty much faded away as a precautionary measure against catching or spreading the virus. Where does that leave us? Public health authorities once suggested we should improve indoor air quality, but most organizations and individuals have ignored that advice. What a shame! It might be the best way to prevent future COVID outbreaks and reduce the likelihood of catching influenza. A new study from Australia suggests that ultraviolet light devices might reduce respiratory infections (JAMA Internal Medicine, July 28, 2025). More about this new study momentarily.

Do You Need to Wear a Mask?

I am not about to suggest you should wear a face mask ever again. It is clear that most Americans hate face masks! Some have dismissed “face diapers” as “virtue signaling.” They refused to wear anything from day one and they won’t change no matter what happens in the future. These folks would be shocked, however, if they needed surgery and the nurses and doctors walked into the operating room without masks.

We have been disappointed that there have not been better, large, well-controlled clinical trials to determine what really does work and what doesn’t. Norwegian researchers describe in excruciating detail the problems that were faced in that country when it came to researching effective strategies for infection control (Trials, Oct. 12, 2024).

Other researchers in Norway reported that (BMJ, July 24, 2024):

“Wearing a surgical face mask in public spaces over 14 days reduces the risk of self-reported symptoms consistent with a respiratory infection, compared with not wearing a surgical face mask.”

But that study leaves a lot to be desired. We need much better data before Americans would contemplate wearing face masks to prevent respiratory infections.

Public Health Officials Let Us DOWN!

Public health authorities really missed the boat at the beginning of the COVID pandemic. They urged Americans to wash their hands and disinfect doorknobs and groceries to prevent the spread of the coronavirus. Face masks were discouraged.

Here is what the World Health Organization (WHO) said back in June, 2020:

“Many countries have recommended the use of fabric masks/face coverings for the general public. At the present time, the widespread use of masks by healthy people in the community setting is not yet supported by high quality or direct scientific evidence and there are potential benefits and harms to consider.”

There is still a lack of high quality research around masks.

The CDC was no better that the WHO. Early in the pandemic we got this from our public health authorities.

The CDC stated:

“If you are NOT sick: You do not need to wear a facemask unless you are caring for someone who is sick (and they are not able to wear a facemask).”

The Surgeon General, America’s Top Doc, went so far as to Tweet:

“STOP BUYING MASKS!” “THEY ARE NOT effective in preventing general public from catching #Coronavirus”

How did this happen? A review of the history of science shows that the experts were misled by past dogma. We now know that SARS-CoV-2 is airborne. Preventing it requires better ventilation and air filtration.

According to Jose-Luis Jimenez, lead author of an analysis of the history of the science of epidemics (ScienceDaily, Sept. 2, 2022):

“History set us up for a poor response to the pandemic.” He observed, “We might have had millions of fewer deaths, hundreds of millions fewer cases, if we’d taken appropriate, effective action from the start.”

Dr. Jimenez and his colleagues introduce their research this way (INDOOR AIR, Aug. 21, 2022):

“Since the early 20th century, there has been resistance to accept that diseases transmit through the air, which was particularly damaging during the COVID-19 pandemic. A key reason for this resistance lies in the history of the scientific understanding of disease transmission: Transmission through the air was thought dominant during most of human history, but the pendulum swung too far in the early 20th century. For decades, no important disease was thought to be airborne. By clarifying this history and the errors rooted in it that still persist, we hope to facilitate progress in this field in the future.”

This in-depth analysis in the journal INDOOR AIR suggests that we need to improve indoor air quality! Full Stop! If we invest in proper ventilation, filtration and other proven strategies, we just might reduce the spread of COVID, influenza and other viral or bacterial infections.

We talked with one of the country’s leading experts on how to improve air quality on our syndicated radio show, Saturday, September 10, 2022 at 7:00 am EDT. Dr. Richard Corsi is Dean of the College of Engineering of the University of California, Davis. Here is a link to the show notes. You can listen to the podcast on this website.

What Can Be Done to Improve Air Quality?

Wouldn’t you feel much more comfortable going into a restaurant, supermarket, pharmacy, bank, elevator or doctor’s office knowing that there were HEPA or MERV13 air filters installed in the air handling system? Such filters can “catch” most viruses and bacteria before we breathe them.

Here is a photo I took at a highly regarded hotel demonstrating the filters they used and how ugly they were:

Used air filters from a public establishment

Our children should be able to enter a school knowing that the administration has done everything humanly possible to improve indoor air quality. In some cases that might mean installing UV devices in the duct work or above a dropped ceiling so that viruses and bacteria are killed before kids breathe them.

Ultraviolet Light vs. Respiratory Infections:

The latest research on germicidal ultraviolet light (GUV) comes from Australia (JAMA Internal Medicine, July 28, 2025). The investigators wanted to know if UV light appliances could reduce the incidence of acute respiratory infections (ARIs) in long-term care facilities for older adults.

The authors introduce their research this way:

“Outbreaks of common respiratory viruses, such as influenza, respiratory syncytial virus, and SARS-CoV-2, are associated with high rates of hospitalization and death for residents of long-term care facilities for older adults (LTCFs; also termed residential aged care or nursing homes). Infection control measures for common respiratory viruses focus on contact or droplet transmission. However, when airborne transmission occurs via infectious respiratory particles, standard precautions, like physical distancing, mask use, and hand hygiene, reduce, but do not eliminate, the risk of infection by viral aerosols. Increased rates of air exchange can reduce the risk of airborne viral transmission but are associated with considerable heating and cooling costs. Therefore, alternative strategies that can protect vulnerable older adult populations from seasonal respiratory virus outbreaks and future pandemics are urgently needed.”

Let’s face it. The people who maintain hospitals, schools, doctors’ offices, pharmacies, supermarkets, religious institutions, banks, sports arenas and most other public buildings do not want to spend tons of money to improve the rates of air exchanges. As the Aussies note, that’s expensive!

The Australian researchers point out that germicidal UV (GUV) air sterilization appliances “use UV light to kill airborne viral, bacterial, and fungal organisms.” The results of this randomized clinical trial were not overwhelmingly positive. They were, however, using an older population of nursing home residents that is extremely vulnerable to respiratory infections.

Overall, there was a 12% reduction in acute respiratory infections when the ultraviolet appliances were being used in common rooms. The investigators concluded that GUV appliances:

“…did significantly reduce the total numbers of ARIs [acute respiratory infections] among older adult residents of long-term care facilities.”

The authors of this research concluded that integrating such UV germicidal devices into ducted heating, ventilation and air conditioning systems could potentially improve air quality and infection control.

Florence Nightingale Worked to Improve Indoor Air Quality:

Do you remember who Florence Nightingale was? She has almost been forgotten by modern medicine. Ms. Nightingale was, however, a brilliant nurse who changed the world of medicine a long time ago. Her observations and recommendations during the 19th century could be useful today in our fight against COVID-19.

Florence was born in Florence, Italy, in 1820 to a well-to-do British family. She was raised in a classic English mansion in Derbyshire, England. Although her parents expected her to marry into another wealthy family, Florence knew from an early age that she wanted to become a nurse. She excelled in mathematics, science and languages.

Unlike other well-to-do young women of that period, our heroine refused a marriage proposal at age 17. At age 24 she traveled to Germany to start nursing studies at the Lutheran Hospital of Pastor Fliedner.

The Crimean War:

A decade later she was asked by the British Secretary of War to lead a team of nurses. British soldiers were fighting alongside their allies from Turkey in Crimea against Russia. Conditions for care of the wounded soldiers were abysmal. She described what she saw as “the Kingdom of Hell.” It was at the British base hospital in Crimea that Florence Nightingale changed the future of medicine.

Her observations and recommendations during the 19th century to improve air quality are useful today in our fight against COVID-19. Nightingale established standards of cleanliness and nutrition that made a huge difference for the soldiers’ recovery. They called her “the Angel of Crimea.” Her 830-page report reformed military hospitals.

Nightingale’s Efforts to Improve Indoor Air Quality!

Upon her return to England, she set up a nursing school that applied scientific principles to the care of the sick. In particular, she emphasized the importance of fresh air as well as good lighting, sanitation and nutrition. The “Nightingale wards” she designed had ample cross-ventilation as well as plenty of natural light. Both were critical to a healthful environment for hospitals.

This was not a by-the-way issue for Florence. In her renowned textbook, Notes on Nursing (1859), the first chapter emphasizes that hospitals should keep the air inside wards:

“…as pure as the external air…”

In other words, good ventilation was crucial for recovery and good health!

Why We Need To Improve Indoor Air Quality Today!

Virologists and epidemiologists are now emphasizing the importance of Nightingale’s ideas. In the late 20th century, builders were looking for ways to save money on energy bills. As a result, they sealed buildings and cut down on fresh air circulation. Florence would be shocked to see hospitals in which windows do not open.

Our modern-day Florence Nightingale is Dr. Linsey Marr. She is a professor of civil and environmental engineering at Virginia Tech, where she leads the Applied Interdisciplinary Research in Air (AIR2) laboratory. Dr. Marr is one of the world’s foremost authorities on airborne viruses.

She has provided valuable information on the aerosol transmission of SARS-Cov-2 in the spread of COVID-19. She advises people to imagine someone smoking in a closed room. If you can smell smoke, you are also exposing yourself to the possibility of inhaling the coronavirus.

Let’s Improve Indoor Air Quality Now!

If we want to control COVID and other viral infections, we will need to take ventilation, filtration and disinfection far more seriously.

An article in JAMA (June 7, 2022) titled “Reducing SARS-CoV-23 in Shared Indoor Air” notes that:

“SARS-CoV-2 replicates in the respiratory tract and spreads through exhalation of infectious respiratory particles. The chances of transmission increase the longer an uninfected person stays in an enclosed space with an infected person. Infection can occur not only through short-range transmission of exhaled respiratory particles from an infectious person resulting in mucous membrane deposition or inhalation of exhaled respiratory particles by an uninfected person. Infection also can occur through long-range transmission from inhalation of infectious respiratory particles that remain suspended in air for longer periods (potentially after the infectious person is no longer present) and across longer distances (greater than a few meters).”

Remember Dr. Marr’s analogy? If you could smell the lingering odor of smoke after someone was puffing on a cigarette or a cigar, you are breathing particles floating in the air. You may not see them, but they are getting into your nose.

People with COVID-19, influenza, measles, tuberculosis, respiratory syncytial virus (RSV), metapneumovirus, parainfluenza, Streptococus pneumoniae, or some other infectious agent are depositing a trail of nasty particles in the air around them. If they walk into a grocery store, post office, bank, pharmacy, restaurant or public restroom half an hour before you enter, they could leave behind aerosolized infectious particles for you to breathe. If you develop symptoms three to five days later you will have no idea where you acquired the infection. It could have been at any one of those places.

Who Will Improve Indoor Air Quality?

It’s time for public health authorities to focus on making it safe to breathe indoors. That will involve radical changes in air handling. To improve air quality, builders will need to rethink ventilation practices.

The people who manage offices, supermarkets, pharmacies, hospitals, schools and all other public buildings will need to retrofit their HVAC systems. What difference could better air quality make?

A study of schools in Georgia found that rates of COVID-19 were 39 percent lower in schools that upgraded their ventilation than in schools that did not (MMWR, May 28, 2021).

An article in JAMA (June 7, 2022) adds this about how to improve indoor air quality:

“A growing list of options exists for structural interventions to prevent COVID-19 through dilution, filtration, and disinfection of shared indoor air. Air handling system upgrades, improvements, or setting changes can reduce viral particle concentrations by bringing in outdoor air to dilute potential contaminants. Using air filters with higher minimum efficiency reporting value (MERV) ratings in HVAC systems can more effectively filter respiratory particles from recirculated air. Portable and commercially available HEPA air cleaners can do the same for a single room without modifying the building’s existing air handling system.”

There are also systems that use ultraviolet (UV) germicidal irradiation. They can be put into duct work or air handling systems.

Improving air quality through better ventilation, filtration and disinfection reduces the risk of infection for everyone who uses the building. Utilizing high-efficiency particulate air (HEPA) filters can also cut exposure to viruses (MMWR, July 9, 2021).

Let’s make make Florence Nightingale proud. Isn’t it time to invest in our health?

Have we whet your appetite for more information? Would you like to learn more about MERV (minimum efficiency reporting value) air filters? Listen to Dr. Richard Corsi on this podcast.

You can also listen to a prior interview with Dr. Linsey Marr, another hero of air quality, at this link. You can stream the audio by clicking on the arrow inside the green circle under Dr. Marr’s photo at the top of the page or you can scroll to the bottom and click on the link that says “Download the free mp3.”

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