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Under growing pressure from researchers, the World Health Organization acknowledged Thursday that the coronavirus can linger in the air indoors and potentially infect people even when they practice social distancing. The United Nations agency had maintained that such airborne transmission occurred only during certain medical procedures and that nearly all infections occur when people inhale respiratory droplets expelled in their immediate vicinity or when they touch contaminated surfaces. (Read, 7/9)

In an open letter published this week in a journal, two scientists from Australia and the U.S. wrote that studies have shown “beyond any reasonable doubt that viruses are released during exhalation, talking and coughing in microdroplets small enough to remain aloft in the air.” The researchers, along with more than 200 others, appealed for national and international authorities, including WHO, to adopt more stringent protective measures. (7/9)

An aerosol is a respiratory droplet so small it may linger in the air. In its latest description of how the virus is spread, the agency said transmission of the virus by aerosols may have been responsible for “outbreaks of Covid-19 reported in some closed settings, such as restaurants, nightclubs, places of worship or places of work where people may be shouting, talking or singing.” (Mandavilli, 7/9)

The World Health Organization has expanded its coronavirus guidance to include the possibility in certain circumstances of airborne transmission, in which the virus could be spread through tiny droplets that linger in the air. The update came Thursday after an open letter signed by more than 200 scientists pressed the agency this week to acknowledge the potential role that tiny droplets, or aerosols, play in airborne transmissions among people in crowded, indoor settings for prolonged periods of time. (Chow, 7/10)