Aerosols from speaking can linger in the air for up to nine hours

• Published in: Building and environment 2021-11, Vol.205, p.108239-108239, Article 108239
• Main Authors: Ding, Shirun, Teo, Zhen Wei, Wan, Man Pun, Ng, Bing Feng
• Format: Article
• Language: English
• Subjects: Aerosols; Air sampling; Airborne transmission; Coronaviruses; COVID-19; Dehydration; Disease transmission; Half-life; Indoor environments; Lifetime; Light scattering; Respiratory diseases; Size distribution; Social factors; Speaking; Speech; Speech aerosol; Viral diseases; Viruses
• ISSN: 0360-1323; 1873-684X
• DOI: 10.1016/j.buildenv.2021.108239

Airborne transmission of respiratory diseases has been under intense spotlight in the context of coronavirus disease 2019 (COVID-19) where continued resurgence is linked to the relaxation of social interaction measures. To understand the role of speech aerosols in the spread of COVID-19 globally, the lifetime and size distribution of the aerosols are studied through a combination of light scattering observation and aerosol sampling. It was found that aerosols from speaking suspended in stagnant air for up to 9 h with a half-life of 87.2 min. The half-life of the aerosols declined with the increase in air change per hour from 28 to 40 min (1 h−1), 10–14 min (4 h−1), to 4–6 min (9 h−1). The speech aerosols in the size range of about 0.3–2 μm (after dehydration) witnessed the longest lifetime compared to larger aerosols (2–10 μm). These results suggest that speech aerosols have the potential to transmit respiratory viruses across long duration (hours), and long-distance (over social distance) through the airborne route. These findings are important for researchers and engineers to simulate the airborne dispersion of viruses in indoor environments and to design new ventilation systems in the future. [Display omitted] •Aerosols from speaking suspended in stagnant air for up to 9 h.•The half-life of the speech aerosols in stagnant air is 87.2 min.•The half-life of the aerosols declined with the increase in ventilation.•The aerosols in size range of 0.3–2 μm had the longest lifetime.