A variety of companies like Windstar Cruises and Shake Shack have announced they are installing UV-C ultraviolet light systems in their air handlers. UV-C kills coronaviruses among other things and is increasingly used in hospitals and other venues.

Why not ask businesses to install UV-C air purification systems and allow them to fully re-open?

This UV technology is not new and was even used in the 1967 Star Trek episode "Operation Annihilate" to rid a colony of a pesky parasite. (Of course, Mr. Spock went blind because of this, but that's because he wasn't wearing proper UV filtering Ray-Bans.)

"Star Trek: The Original Series" Operation - Annihilate! (TV Episode 1967) - IMDbDirected by Herschel Daugherty. With William Shatner, Leonard Nimoy, DeForest Kelley, James Doohan. The Enterprise crew attempts to stop a plague of amoeba-like creatures from possessing human hosts and spreading throughout the galaxy.www.imdb.com

I'll admit that I know nothing about this topic and haven't read the linked articles, but surely this doesn't address the issue of people in close proximity to each other spreading any kind of virus between themselves long before that air gets sucked out of the space and filtered?

Most commercial venues run air handlers continuously, otherwise it gets stuffy fast. Many have installed HEPA filters already, so the air purification concept is already well-known and understood. An extreme example are airplane air handling systems that continuously inhale air from the outside, flow it through the cabin and then eject it back out.

It’s a very fascinating question. My understanding is microbes need more than momentary exposure to UV C to die so the exposure you can give to microbes as air rushes by is low. So big air filtration systems rely on HEPA filters more often than not. It makes me wonder if there is an innovation to be had around lengthening the air passageways or something to expose the microbes longer.

This guy seems to know how it works on commercial aircraft:

Do commercial aircraft use UV-C light to help clean the cabin air?Answer: Where are these CRAZY ideas coming from????????????? Here is how a modern airliner works: All of the air in the airplane is tossed over board, roughly once per hour. About six times per hour, half of the air is definitely "tossed overboard". The remaining half is sent through a special...www.quora.com

These UVC light emitters in hospitals seem to have real utility, though:

Ultraviolet and HVAC: Keys to reducing hospital acquired infections - Hospital NewsThe use of ultraviolet light systems is becoming more widely used in healthcare facilities for disinfecting patient and operating rooms. Yet, ultraviolet lights systems are misunderstood in spite of significant research and use in other industries. So let's unravel this mystery. Ultraviolet (UV) light in nature is electromagnetic radiation produced by the sun.hospitalnews.com

Are you thinking of investing in UVC tech?

This is an excellent article describing exactly how air flows through an airplane with a nice interactive graphic that walks you through the various airplane air handling components.

The Greatest Coronavirus Risks When You FlyThe plane's air filters and blocked middle seats help prevent the spread of Covid-19 and other viruses, but hazards remain.www.wsj.com

I haven't been presented with any immediate investment opportunities in UV-C or related air handling systems, though we did see the Molekule air purification company. (FD: I am not an investor.) It wouldn't be surprised if they and others add UV-C to their products.

Air Purification, Reinvented by MolekuleAir purifiers, reinvented. Molekule's award-winning PECO technology destroys pollutants like viruses, bacteria, mold & more.molekule.com

It's probably just a matter of time before we see UV-C air purification deals. We've already seen a variety of COVID testing and detection deals using a variety of different technologies.

It would take more than installing the system. The entire airflow would have to be addressed. It doesn't help if the virus is simply blown from one table to the next across a crowded room on its way to the intake duct.

Yeah - that's the way I see it too.

The entire volume of air would also have to be contained long enough for the UV to work. And you can't just have the UV's in the shops because the level of intensity required to kill the virus quickly is also harmful to human skin.

Maybe they could swallow the lights. :-)

This is accurate. The biggest risk of transmission is person-to-person, not environmental. UV would be a good solution to airborne particles, but COVID-19 is not airborne. Some of the largest clusters in Malaysia come from shared residences where people are in close proximity to each other several hours a day. There have been isolated cases in shopping malls, but no clusters have emerged from said malls, supporting the idea that the virus doesn't linger around in the air.

The best preventive measures are still face masks and social distancing.