Infectious diseases: Older people exhale significantly more aerosols
German researchers show: The breath of younger people contains significantly fewer aerosol particles
Source: Getty Images
It was an important parameter during the corona pandemic: the number of viruses in the air that a person excretes. Now German researchers are realizing: the older, the bigger. Not young, but older people emit significantly more particles.
WDuring the corona pandemic, an important question was: How many aerosols do people of different ages expel with the air they breathe? Opinions sometimes differed when it came to the answer, and it was followed by such tough measures as school closures – with all their consequences. For this reason alone, it is important for scientists to record as precisely as possible how many tiny solid and liquid particles are emitted by children, young people and the elderly. After all, pathogens such as viruses or bacteria can spread through them.
The team led by Benedikt Schumm from the Bundeswehr University in Munich in Neubiberg has now looked into the question again. In the journal Proceedings of the US National Academy of Sciences (PNAS), the scientists note that older people emit two to three times as many droplets with their exhaled air as younger people.
“The airborne transmission of pathogens such as Sars-CoV-2, flu or cold viruses through aerosol particles plays an important role in the spread of infectious diseases‘ the authors write. They wanted to find out how the amount of aerosols differs between rest and exercise and what role age, gender and body mass index (BMI) play. To do this, they used a new method to measure the exhaled air and the aerosols it contained in 40 healthy women and men aged 20 to 39 and 60 to 76 years.
At rest, older people emit three times as much aerosol
The age difference was the most significant: when at rest, the concentration of aerosol particles was on average three times higher in older people than in younger people. During physical exertion, the amount of exhaled aerosol particles increased by up to 50 times in younger people and up to 40 times in older people than at rest. Even with the highest achievable athletic performance, the concentration of the older people was more than twice as high as that of the younger ones.
Age was decisive for the aerosol concentration differences. Gender or body size did not play a role
Source: Getty Images
Gender, on the other hand, played a subordinate role: when at rest, the air breathed by older women contained on average more aerosols than the air breathed by older men. However, older men had a 24 percent greater tidal volume than older women. Younger men even moved 61 percent more air than younger women.
Because the higher volume of males offset the higher aerosol concentration of females, there was no significant difference in aerosol output between sexes of the same age group. The body mass index could not explain individual differences either.
The formation of the aerosols goes back, among other things, to the constant contraction and opening of the small airways in the lungs when breathing. “The cycle is associated with the periodic rupture of the liquid film covering the mucous membrane, which leads to the formation of aerosols,” explain Schumm and colleagues. An increased emission of aerosol particles is a hitherto undescribed characteristic of the aging of the human lung.
The researchers also measured the size distribution of the aerosol particles: it was shifted towards larger particles in older people compared to younger people. The team concludes that aerosols from older people could potentially transport more pathogens: “This is important information for planning containment measures, especially for indoor sports facilities during waves of infection or future pandemics.”
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