Coronavirus FAQs: Can Sunlight Kill The Virus? How Risky Is An Elevator Ride?

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Can sunlight kill the coronavirus? What about UV light?

Sunlight contains three types of ultraviolet light — UVA, which tans your skin (and ages it) and can cause eye damage; UVB, which burns and also ages skin; and UVC, which is "the most harmful one" because it's quite good at destroying genetic material, explains Juan Leon, a virologist who focuses on environmental health at Emory University. Luckily, he notes, the sun's UVC rays don't reach us because they are filtered out by Earth's atmosphere.

Sunlight can be a good disinfectant with other pathogens. Leon notes that's why in the developing world, the World Health Organization recommends sterilizing water by putting it in plastic containers and leaving it outside in the sun for about five hours.

"Right now, there is no data on whether the UVA rays of the sun can inactivate this coronavirus," says Leon. However, research on SARS, another coronavirus closely related to the one causing the current pandemic, found that exposing that virus to UVA light for 15 minutes did nothing to reduce its infectivity, Leon says.

The results with UVC light were more promising, notes virologist Julia Silva Sobolik, a researcher in Leon's lab at Emory. "UVC for longer durations, over 15 minutes, was found to be more effective at inactivating SARS," she says.

In fact, UVC light is frequently used to sterilize equipment in medical settings, says Leon.

But while UVC products are available for consumers to buy, there aren't really any uniform performance standards, and testing validation can vary greatly, according to the International Ultraviolet Association. Besides, UV light of any kind can be harmful to eyes and skin — and UVC is the most damaging kind, so you'd have to be extra-careful and properly trained not to seriously hurt yourself, experts say. (And you definitely shouldn't try to use any kind of UV light to disinfect your body, the WHO has warned.) For disinfecting your body, soap and water will do the trick.

That said, researchers believe UVC light has a part to play in the fight against the coronavirus. In China and Italy, UVC-wielding robots reportedly are being deployed to disinfect hospitals.

If I step into an elevator where an infected person has recently been, could I get the virus?

Perhaps you live in a building with an elevator, you ride in one at work or you use one at the grocery store with a full cart. Maybe you're facing an empty elevator and are worried. Could a person with COVID-19 have just been in that space? Should you worry about viral particles in the air?

The Centers for Disease Control and Prevention says current data suggest that the primary mode of transmission is through respiratory droplets from an infected person that can land in the mouths, noses or eyes of people nearby or possibly be inhaled into the lungs of those within close proximity. The virus is also believed to spread by touching a contaminated surface and then touching your eyes, nose or mouth.

What about smaller viral particles in the air? The CDC says the role of "small respirable particles, sometimes called aerosols or droplet nuclei, to close proximity transmission is currently uncertain. However, airborne transmission from person-to-person over long distances is unlikely."

As NPR's Nell Greenfieldboyce has reported, the question of how the virus moves through the air is something scientists are still trying to understand — and disagree about. Even if traces of the virus can be found in the air if an infected person breathes or speaks, it's not clear that the concentration is high enough to transmit the virus.

Linsey Marr is an aerosol scientist at Virginia Tech, and she believes that transmission by inhalation of virus in the air is happening.

"I would be concerned about elevators because they are a confined space," she said in an email interview with NPR. "Many elevators do not seem to have mechanical ventilation, like a fan, beyond the natural ventilation that occurs when the doors open and close and some leakage that always occurs with any room."

But Dr. Daniel Griffin, an infectious diseases expert at Columbia University, says he believes the air in elevators doesn't pose a risk unless some very particular event just happened there that generated aerosols. Certain medical procedures, such as inserting a tube into an airway, are likely to generate higher concentrations of infectious respiratory aerosols. Vomiting can also produce aerosols, Griffin says.

"Unless someone had just vomited in that elevator and aerosolized [the viral particles] or someone had just been intubated in that elevator, you're OK," he says.

The respiratory particles that are the main spreader of the virus fall to the ground quickly after a cough or sneeze, Griffin says. "You can think of these small wet balls that are flying through the air when someone coughs or sneezes — and they're traveling pretty fast, but they're large enough that they're actually heading toward the ground due to gravity."

So the main thing to watch out for is the surfaces of the elevator, especially the buttons.

"Everyone is going to be pushing the same buttons with their hands," he says. "You got to do something if you're going to touch the buttons."

If you are, either wash your hands or use hand sanitizer afterward.

And if possible, try to ride the elevator only with people in your household. Unless the elevator is huge, it will be hard to keep 6 feet of social distance.

Can I safely let a repair person into my home?

With everything else happening, this is an unfortunate time to need repairs. So what do you do?

Wait, if you can. It can be difficult in some cases to get someone to come. Say your Internet is down. Verizon says that for now, as part of precautions to keep employees and customers safe, "our technicians will not be able to enter your home for new services or to do repair work." It says self-setup remains an option where it's available, and it'll ship the necessary equipment.

Meanwhile, AT&T has advised its technicians to contact customers prior to arriving for scheduled appointments to ask questions concerning health and travel. Technicians have been instructed not to go inside the home or business of any customer who has been sick or quarantined, traveled to a high-risk Level 3 country in the last 14 days or been in close contact with someone confirmed positive for the coronavirus or who traveled through a high-risk country in the last 14 days.

Trane, which makes air conditioners and heat pumps, said in a statement that its service technicians are still taking appointments. It recommends calling your local provider to ask if it is taking the CDC's recommended steps for facilities, including checking employees for fever and cleaning surfaces often.

A few other commonsense tips from Trane if you do need an emergency repair: Have discussions outside, if possible. Wipe any door handles the technician may need to touch. Don't share pens and paper. Keep your distance and don't shake hands.

Consumer Reports has some suggestions too: Inquire about whether the technician will wear a mask. Talk to the service person in advance about a plan to maintain social distance. And after the technician leaves, clean the area where the person was working — here's the CDC-approved list of disinfectants against the coronavirus.

Meanwhile, don't just think of yourself. Trane's boldface request: Don't schedule a service appointment if anyone in your home is showing symptoms. You could infect the repair person.