PM₁, PM_2.5 and PM₁₀ size fraction distribution under steady-state conditions in a walk-in type ²²²Rn calibration chamber facility

Attachment of Rn-222 progenies, upon their formation, to the atmospheric aerosols and inhalation of these radioactive aerosols causes inhalation dose to the human being. Aerosols have the characteristics of small particle size, long-time suspension and long-distance transmission and easy access to the deep respiratory tract. Aerosols are responsible for viral infection risk such as the recent worldwide pandemic caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2, or COVID-19). Understanding the formation and behaviour of aerosols in a confined environment in various human habitations is essential to combat such detrimental exposures. Experiments have been performed to study the distribution of aerosol size fractions in the walk-in type Rn-222 calibration chamber. The real-time applied particle technology monitors (APT-Maxima stationary monitors) were used for the simultaneous measurements of PM1, PM2.5, and PM10 size fractions. The variation of the mass densities (mu g m(-3)) of different size fractions at different positions inside the chamber was monitored by placing APTs. The PM1, PM2.5, and PM10 sizes fractions were distributed homogeneously within the chamber volume and the concentration ratios of these fractions were 1:1.5:1.6 for concentration values of < 1500 mu g m(-3), and 1:7:9 for the concentration values of > 1500 mu g m(-3).