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


      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 5 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.


      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 who are 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."


      The main thing to watch out for is the surfaces on the elevator: especially the buttons.


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