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Particles exhaled by diseased people frequently serve as a means of disease transmission. However, depending on where in the respiratory system they originate, such aerosol particle size differs significantly. The lung mostly produces PM5, or small particles, that are less than five microns in size, or five-thousandths of a millimetre. The upper respiratory tract, however, produces larger particles.
Children breath significantly fewer tiny particles than adults do, the measurements revealed. We discovered that the concentration of tiny particles under five microns rises with age and is especially low in children. Therefore, if the illness primarily affects the lower respiratory tract, adults are much more likely to cause spreading, according to Mohsen Bagheri, research group leader and study's primary author at the MPI-DS. The study found that toddlers and adults both disseminate bigger particles that start in the throat to the same degree. The amount of inhaled particles did not correlate with a person's gender, weight, level of physical activity, or smoking habits, according to the study. Vocalisation activities increase small particle concentration In this comprehensive study, the researchers recorded data from 132 healthy volunteers. The study also included children and adolescents between 5 and 18 years about which very little data were available. They used various instruments installed in a clean room to measure the full range of particle sizes exhaled: from a tenth of a micrometer to a quarter of a millimeter. The participants performed different vocalization activities such as singing, speaking and shouting for 20 minutes in total. "Vocalisation and age are shown to be independent risk factors for particle production," said Prof. Simone Scheithauer from the Department of Infection Control and Infectious diseases at the UMG. The volume of the exhaled particles determines potential infection risk Although human drops and aerosols contain mostly small particles, larger particles constitute the major part of the total volume that can contain pathogens. "If the pathogen mainly resides in the upper respiratory tract, the large particles are by far the main transmitter of the disease", said Eberhard Bodenschatz, director at the MPI-DS, adding, "It is thus important to consider the localization of the infectious particle in the respiratory tract to decide on appropriate protection." he continued, "For example, the current Omicron variant of the Coronavirus seems to be localized more to the upper respiratory tract and this is why even simple filtering face masks are a great protection." Protective measures depend on the localisation of the pathogen In contrast, Infectious diseases that reside mainly in the lungs will primarily be transmitted via small particles. Since their production increases with age, children are less likely to transmit such diseases than adults, according to the study. To prevent airborne transmission of lung diseases, wearing of well-fitted and high-efficiency facial masks can thus be an effective measure to avoid disease transmission, especially for adults. (ANI)
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