Not to be a party pooper, but the “Happy Birthday” song may be the latest COVID casualty.
Despite early advice to sing “Happy Birthday” while hand-washing to ensure sufficient cleansing, health experts are now warning that the song may be a particularly potent vehicle for the spread of COVID-19.
Researchers at Lund University in Sweden observed the trajectory of aerosols emitted by 12 people singing different songs, and discovered that consonant-heavy lyrics, such as the hard Ps and Bs of the birthday song, send comparatively more droplets into the air.
“Different restrictions have been introduced all over the world to make singing safer,” said Jakob Löndahl, an associate professor of aerosol technology. While previous case studies have revealed superspreader events seemingly caused by singing, “there has been no scientific investigation of the amount of aerosol particles and larger droplets that we actually exhale when we sing,” the author said in a statement on the university website.
Respiratory droplets, which may become aerosolized — meaning small enough to be carried in the air — are expelled as we talk, and even more so when we laugh, yell or sing.
“Some droplets are so large that they only move a few decimeters from the mouth before they fall, whereas others are smaller and may continue to hover for minutes,” said co-author and doctoral student Malin Alsved.
“In particular, the enunciation of consonants releases very large droplets and the letters B and P stand out as the biggest aerosol spreaders,” said Alsved, whose experiment used Swedish children’s song, “Bibbis pippi Petter.” The song bears similarities in the amount plosive sounds, or those emitted by the consonants T, K, P, D, G and B, as the American “Happy Birthday” song.
Their study included data from two singers who had tested positive for the coronavirus.
“Their air samples contained no detectable amount of virus, but the viral load can vary in different parts of the airways and between different people,” Alsved explained. “Accordingly, aerosols from a person with COVID-19 may still entail a risk of infection when singing.”
However, face masks, social distancing and proper indoor ventilation can help prevent singing-induced sickness, according to study authors, who hope their report will help better inform choirs and choral groups on how to sing safely during the COVID-19 pandemic.
“When the singers were wearing a simple face mask this caught most of the aerosols and droplets and the levels were comparable with ordinary speech,” said Löndahl, whose report was published in the journal Aerosol Science and Technology. “Singing does not need to be silenced, but presently it should be done with appropriate measures to reduce the risk of spreading infection.”
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