This study determined the efficacy of face masks at reducing exhaled particles in children, as well as whether the type of activity affected the concentration and size of particles.
Children have notoriously high rates of circulating viruses. Respiratory viruses, like COVID-19, are transmitted through respiratory droplets and aerosols, which are expelled via breaking, talking, singing, coughing, and sneezing.
With this knowledge, the outbreak of the COVID-19 pandemic led to myriad recommendations or requirements for face masks. When masking was widely implemented, public health agencies noted significantly lower rates of viral respiratory infections.
However, there has been little investigation into the production of exhaled particles during common activities, and the effectiveness of face masks in children. A recent pediatric investigation, published in Wiley Online Library, sought to determine the effect of type of activity and mask usage on exhaled particle production in children.
The prospective crossover study included 22 children 3-17 years of age, averaging 10.2 years old and 59.1% female. The children were asked to perform activities that expel particles, including breathing quietly, speaking, singing, coughing, and sneezing, while wearing either no mask, a cloth mask, or a surgical mask.
During each activity, the investigators examined the effect of face mask used on the concentration and size of exhaled particles produced. Concentration (number of particles/cm3) and size of particles were monitored in real-time and recorded with an Aerodynamic Particle Sizer (APS) Model 3321.
Predictably, the average exhaled particle concentration increased based on the activity’s intensity. The lowest particle concentration was recorded during tidal breathing (1.285 particles/cm3 [95% CI 0.943, 1.627]), while the highest concentration of particles was expelled during sneezing (5.183 particles/cm3 [95% CI 1.911, 8.455]). High intensity activities were also associated with an increase in the size of respirable particles (particles ≤ 5 µm are respirable size).
Surgical and cloth masks were associated with lower average particle concentrations, compared to not wearing a mask. Surgical masks performed better than cloth masks across all the activities, and especially helped to reduce the size of the respirable particles. For sneezing, the highest intensity activity, cloth masks reduced total exhaled particle release by 45.6%. Surgical masks reduced the total particles exhaled during sneezing by 54.1%.
Notably, the children were surveyed after the study to rate their experiences wearing each type of mask. At 64%, most children indicated they would prefer to wear cloth masks over surgical masks in school, and 72.7% reported their favorite mask type was cloth. The participants reported an overall better experience wearing the cloth mask compared to the surgical mask, but rated the breathability of surgical masks better than the cloth masks.
The investigators concluded that children produce exhaled particles, varying in size and concentration, at rates similar to adults. Coughing and sneezing were associated with a higher production of exhaled particles, with the study authors writing, “Higher production was particularly observed in the respirable size fraction, reflecting the formation of smaller exhaled particles during activities with a greater expiratory flow.”
Average particle concentration increased more significantly during high-intensity activities in older children than in younger children. The investigators emphasized their findings that face masks work equally well to reduce exhaled particles across all ages.