Singing Happy Birthday could spread Covid-19 because the enunciation of Bs and Ps releases large droplets which may be infectious, study warns
Singing happy birthday may be good for timing how long to wash your hands, but a new study reveals it could also be spreading coronavirus infected droplets.
Aerosol researchers at Lund University, Sweden studied the amount of particles emitted when we sing, and the impact this has on the spread of Covid-19.
To understand how many virus particles are emitted when we sing, researchers had 12 healthy singers and two people with Covid-19 sing into a funnel.
The study shows that singing – particularly loud and consonant-rich singing found in songs like Happy Birthday – spreads a lot droplets into the surrounding air.
Researchers say if singers wear a face mask and venues practice social distancing and implement good ventilation, then the risk from singing can be reduced.
The NHS recommended people sing 'Happy Birthday' twice while washing hands as it was the perfect amount of time to ensure as many germs as possible are removed.
To understand how many virus particles are emitted when we sing, researchers had 12 healthy singers and two people with Covid-19 sing into a funnel
The idea for the study came off the back of a number of reports about the spread of Covid-19 in connection with choirs singing together, researchers explained.
HAPPY BIRTHDAY POSES A RISK DUE TO 'P' AND 'B' SOUNDS
Researchers say songs with a lot of consonants are particularly risky to sing as they push more droplets.
Songs with a higher proportion of 'B' and 'P' sounds pose the greatest risk.
This includes 'Happy Birthday', the song recommended by the NHS to time hand washing at the start of the Coronavirus crisis.
Happy Birthday lyrics:
Happy Birthday to You
Happy Birthday to You
Happy Birthday Dear Name
Happy Birthday to You
'Different restrictions have been introduced all over the world to make singing safer,' according to study author Jakob Löndahl, associate professor of Aerosol Technology.
'So far, however, there has been no scientific investigation of the amount of aerosol particles and larger droplets that we actually exhale when we sing', he said.
Aerosols are small airborne particles - some of these particles are larger than others and the larger ones only move a small distance from the mouth.
'Some droplets are so large that they only move a few decimetres from the mouth before they fall, whereas others are smaller and may continue to hover for minutes,' said co-author Malin Alsved, a doctoral student.
'In particular, the enunciation of consonants releases very large droplets and the letters B and P stand out as the biggest aerosol spreaders', Alsved added.
During the research experiments singers had to wear clean air suits and enter a specially built chamber supplied with filtered, particle-free air.
In the chamber, analysis was conducted of the number and mass of particles emitted by singers during breathing, talking, different types of singing and singing with a face mask.
What they sang was a short and plosive-rich Swedish song, 'Bibbis pippi Petter', which was repeated 12 times in two minutes at constant pitch.
The same song was also repeated with the consonants removed, leaving only the vowels, according to the research team.
During the song tests, aerosols and larger droplets were measured using lamps, a high-speed camera and an instrument that can measure very small particles.
The louder and more powerful the song, the greater the concentration of aerosols and droplets, the researchers discovered.
'We also carried out measurements of virus in the air close to two people who sang when they had Covid-19, explained Alsved.
'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.
'Accordingly, aerosols from a person with Covid-19 may still entail a risk of infection when singing', the researcher said.
During the research experiments singers had to wear clean air suits and enter a specially built chamber supplied with filtered, particle-free air
What they sang was a short and plosive-rich Swedish song, 'Bibbis pippi Petter', which was repeated 12 times in two minutes at constant pitch
The researchers say that if we have a good understanding of the risks involved when a group of people sing together, we can also sing in a safer way.
The song can be sung with social distancing, good hygiene and good ventilation, which reduces the concentration of aerosol particles in the air.
Face masks can also make a difference in reducing the spread of droplets.
'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', says Löndahl.
'Singing does not need to be silenced, but presently it should be done with appropriate measures to reduce the risk of spreading infection'.
The findings have been published in the journal Aerosol Science and Technology.