Respiratory Aerosol Emissions from Vocalization: Age and Sex Differences Are Explained by Volume and Exhaled CO2

Evidence suggests that airborne transmission of infectious respiratory aerosol plays an important role for the SARS-CoV-2 virus. This work characterized respiratory aerosol emissions from a panel of healthy individuals of varying age and sex while talking and singing in a controlled laboratory setting. Particle number concentrations between 0.25 and 33 μm were measured from 63 participants aged 12–61 years with concurrent monitoring of voice volume and exhaled CO2 levels. On average, singing produced 77% (95% CI: 42,109%) more aerosol than talking, adults produced 62% (CI: 27,98%) more aerosol than minors, and males produced 34% (CI: 0,70%) more aerosol than females. After accounting for participant voice volume and exhaled CO2 (both of which were positively correlated with aerosol emissions) in linear models, the age and sex differences were attenuated and no longer statistically significant. These results support further investigation of voice volume and CO2 as indicators of infection risk indoors.