Can UV Light Inactivate Airborne Human Coronavirus?

December 31, 2019, China reported a case of pneumonia from an unknown cause to the World Health Organization.¹ It wasn't long afterward that it became apparent that the "unknown cause" would create global havoc.

Immediately, scientists began scrambling to find ways to kill the SARS-CoV-2 virus, treat the infection and develop public health policies to contain the spread. Historically, scientists identified coronaviruses responsible for human infection in the mid-1960s.² By 2003 when SARS first appeared, researchers had only identified four subgroups of coronavirus that could infect humans.

But then, also in 2003, SARS-CoV appeared and joined the list. In 2012, the Middle East Respiratory Syndrome (MERS) was identified in Saudi Arabia. And, finally, the most recent addition to this list is SARS-CoV-2.

When it comes to fighting them, one method of disinfecting bacteria and viruses, including coronaviruses, in hospitals has been ultraviolet light. This is one wavelength in the light spectrum that's found in light from the sun, which provides the primary means of killing pathogens in the environment through UV radiation.

In 2005, a team of researchers reviewed the estimated amount of time it took to inactivate viruses using exposure to UVA and UVB radiation from the sun.³ They developed a predictive model that they concluded "should be a useful step to understanding and eventually predicting the survival of viruses after their release in the environment."

Company Claims New Lightbulb Can Kill Coronavirus

In a recent development, one of the largest lighting companies in the world, Signify, says they have developed a new light bulb they believe can kill 96% of coronavirus in just three seconds.⁴ The organization partnered with Boston University to test the effectiveness of the lightbulb to inactivate the virus.

Eric Rondolat, CEO, spoke to CNBC, telling the reporter that after six seconds of exposure, the rate of pathogen death goes up to 99%.⁵ In a press release on Signify's website, Anthony Griffiths, Ph.D., from Boston University School of Medicine is cited:⁶

"Our test results show that above a specific dose of UV-C radiation, viruses were completely inactivated: in a matter of seconds we could no longer detect any virus. We're very excited about these findings and hope that this will accelerate the development of products that can help limit the spread of COVID-19."

Rondolat believes the light bulbs are a preventive measure that may be useful in all types of public places. The notice from Signify follows research from Columbia University, where researchers found low doses of far-UVC light "inactivated 99.9% of aerosolized alpha coronavirus 229E and beta coronavirus OC43."⁷

These scientists found that viral inactivation took approximately 25 minutes. They believe that by doubling the intensity, they may be able to cut the disinfection time in half and still maintain safety.

Researchers Using Far-UVC to Reduce Potential Damage

There are three major types of ultraviolet light: UVA, UVB and UVC. UVA and UVB penetrate the atmosphere and reach the Earth. UVA can penetrate the skin while high levels of exposure to UVB can damage the skin's DNA.⁸

UVC, however, is the most damaging. The wavelengths are between 100 and 290 nanometers, which are almost completely absorbed in the atmosphere.⁹ The wavelength is highly energized and effective as a decontaminant since it destroys the molecular bonds in bacterial and viral DNA.

In one study using UVC to decontaminate hospital rooms and surgical tools, Duke University researchers found that sanitizing a room with UVC light in addition to traditional cleaning reduced the transmission of drug-resistant bacteria by 30%.¹⁰

The danger in working with UVC light is that it not only kills bacteria and viruses, but also damages human DNA. Dan Arnold works for UV Light Technology providing UV disinfecting equipment in the U.K. He spoke with BBC about the potential for using UVC light to disinfect skin and clothing, saying, "You would literally be frying people."¹¹

A study from Columbia University, however, published in Scientific Reports in 2018, generated excitement about the potential for reducing the spread of influenza by using far-UVC.¹² Researchers used continuous low dose far-UVC light and found results which suggested that using this technique in public places may reduce the number impacted by flu, without penetrating human skin or eyes.¹³

Doorway Portal Douses Patrons in UVC Light

Before the results of the light tests from Boston University were published, one bakery announced plans to install far-UVC light bulbs in the stores and at a portal above the doorway. The New York Post reported that Magnolia Bakery "is installing futuristic-looking portals and purple-hued ceiling lights that will drench patrons and workers in potentially disease-destroying far-ultraviolet light."¹⁴ 

The chief baking officer called their store "experiential," saying their customers enjoy spending time in their shop in the Upper West Side. In an attempt to accommodate the needs of their customers and possibly reduce airborne SARS-CoV-2, they are also replacing the indoor lighting with far-UVC light bulbs.

This move has caught some experts by surprise. In March 2020, the Food and Drug Administration released guidelines on the use of disinfectant devices, sterilizers and air purifiers during the pandemic.¹⁵ Karl Linden, environmental engineer, spoke to a reporter at Discover Magazine, saying:¹⁶

"I was quite shocked to see this portal come out … my excitement [is] tempered with the concern that it could be an application that could have some dangerous side effects or direct effects."

It appears that far-UVC lights do not have the immediate and direct effects that regular UVC light has on mammal skin. David Brenner, Ph.D., from Columbia University is one of the scientists in the study showing that low dose far-UVC light inactivates human coronavirus. He spoke with a reporter from the New York Post about the safety of the lights.

Thus far they have tested far-UVC lights on hairless mice for eight months and have not seen any evidence of damage, he said.¹⁷ However, while concentrated forms of UVC are being used to clean city buses in China, hospital floors and even money,¹⁸ the long-term effects of far-UVC light on human skin may require a lengthier test period than just eight months. 

What About Sunlight?

Sunlight is used in developing countries to help sterilize water. The World Health Organization recommends using a process pioneered in the 1980s that involves the sun, a bottle and a black surface. A transparent bottle is placed horizontally for five hours.¹⁹

Field studies in China, Columbia, Bolivia and elsewhere show it helps kill pathogens and reduce the incidence of diarrhea. How long sunlight may take to disinfect surfaces or viruses suspended in the air is still under investigation, though.

During a press conference, William Bryan from the Department of Homeland Security presented results from a study evaluating how long sunlight might take to kill SARS-CoV-2, or if it could. It was found that under ordinary circumstances, when humidity was low at 20% and the temperature was 70 to 75 degrees Fahrenheit, it took about an hour for the virus to be inactivated.²⁰

When sunlight was added to the experiment, it took about 1.5 minutes. The final results of this study have not been made public as yet, nor have they been peer reviewed. However, a report of the results was leaked and picked up by Yahoo! News.²¹ The briefing on the results was marked for "official use only." Yahoo! News reported:

"The study found that the risk of 'transmission from surfaces outdoors is lower during daylight' and under higher temperature and humidity conditions. 'Sunlight destroys the virus quickly,' reads the briefing."

The Department of Homeland Security did not answer a reporter's questions from Yahoo! News and cautioned the public against making a conclusion based on the data from the National Biodefense Analysis and Countermeasures Center, which is a lab that was developed to address bioterrorism after the 9/11 attack. A statement from the Department of Homeland Security read:²²

"The department is dedicated to the fight against COVID-19, and the health and safety of the American people is its top priority. As policy, the department does not comment on allegedly leaked documents. It would be irresponsible to speculate, draw conclusions, or to inadvertently try to influence the public based upon a document that has not yet been peer-reviewed or subjected to the rigorous scientific validation approach."

Vitamin D Level Must Reach 60ng/mL Before Fall

Sunlight is necessary to support optimal health. Scientists have now found those who are deficient in vitamin D, which your body makes with exposure to the sun, have a far higher risk of severe disease from SARS-CoV-2. There is also evidence that SARS-CoV-2 responds to humidity and temperature, causing different scientists to expect another wave of illness in the fall.²³

This means there is a "deadline" before which it is important to optimize your vitamin D levels. To improve your immune function and lower your risk of viral infections, I suggest raising your vitamin D to a level between 60 nanograms per milliliter (ng/mL) and 80 ng/mL by fall. In Europe, the measurements you're looking for are 150 nanomoles per liter (nmol/L) and 200 nmol/L.

To determine if you need to use a supplement, it's important to test your vitamin D levels first. This easy-to-use, at-home vitamin D test kit from GrassrootsHealth can help identify if you need a supplement. I provide this kit as a convenience for my readers; I don't make any money from the sale of this kit.

As I've written before, low levels of vitamin D are commonly found in those with comorbid health conditions or dark skin. This raises the potential risk from COVID-19 and other infectious diseases. To learn more and develop a plan to raise your vitamin D levels by fall, see "Your Vitamin D Level Must Reach 60ng/mL Before the Second Wave."

The Importance of Testing Your Vitamin D Levels

A growing body of evidence shows that vitamin D plays a crucial role in disease prevention and maintaining optimal health. There are about 30,000 genes in your body, and vitamin D affects nearly 3,000 of them, as well as vitamin D receptors located throughout your body.

For a more detailed and comprehensive analysis of the connection of vitamin D and COVID-19, please review the report I created that could be used to address any health care professionals who would disagree with this recommendation. Also included is a shortened version of the document which will be better to educate those that you would like to convince of the importance of getting your vitamin D levels optimized.

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Vitamin D Helps Protect Against Cancer and Other Diseases

According to one large-scale study, having optimal vitamin D levels can slash your risk of cancer and can help prevent at least 16 different types of cancer, including pancreatic, lung, ovarian, prostate and skin cancers.

Vitamin D from sun exposure also radically decreases your risk of autoimmune diseases such as multiple sclerosis (MS) and Type 1 diabetes. Sun exposure also helps prevent osteoporosis, which is a significant concern for women in particular.

Magnesium Is Necessary to Activate Vitamin D

Since over half the population does not get enough magnesium and far more are likely deficient, magnesium supplementation is recommended when taking vitamin D supplements. This is because magnesium helps to activate vitamin D, as the enzymes that metabolize vitamin D in your liver and kidneys require magnesium.

What GrassrootsHealth observed in testing and analyzing nutrient intakes from over 15,000 patients is that about half of those taking vitamin D supplements were unable to normalize their vitamin D levels until they started to take supplemental magnesium.

They also found that those who do not take supplemental magnesium need, on average, 146% more vitamin D per day to achieve a healthy blood level of 40 ng/ml (100 nmol/L), compared to those who take at least 400 mg of magnesium along with their vitamin D supplement.

Omega-3 Fats Are Crucial to Your Well-Being

Meanwhile, recent research suggests high doses (4 grams) of the omega-3 fats EPA and DHA may help improve healing after a heart attack. Other benefits of omega-3 fats include prevention of lupus and Parkinson's disease, decreased anxiety, healthier and stronger bones, as well as fighting fats in the body.

However, you can't tell by looking in a mirror if you are deficient in vitamin D, magnesium or omega-3s. The only real way to know if you are deficient in these nutrients is to get tested.

How Much Vitamin D Should You Take

If you know your vitamin D level you can use the calculator below to find the best dose to take.

If you are unable or unwilling to get a vitamin D test, they have found that the average dose to achieve a healthy vitamin D level of 40 ng/ml is about 8,000 units per day. If you are underweight you will want to reduce this dose to 6-7,000 units per day as heavier people tend to need more vitamin D.

How to Test Your Levels

I'm really pleased GrassrootsHealth Nutrient Research Institute has expanded its research projects to include a range of different tests, seeing how deficiency may be needlessly affecting the health of so many. Like its Vitamin D*action Project, the Magnesium*PLUS Focus Project will allow us all to take action on known science with a consensus of experts without waiting for institutional lethargy.

The Vitamin D*action Project has truly demonstrated the value measurement can have on public health, and there's no doubt in my mind that the Magnesium*PLUS Focus Project will have the same impact. As in earlier projects, once the study of a community is completed, all that information can be used to push for public health recommendations that will benefit everyone. You have the ability to participate in a variety of different tests, including:

With the data from this project, individuals will be able to see what works for them, and, researchers will be able to demonstrate just to what extent health care costs may be reduced simply by getting people into an optimal range.