Experimental and simulation study on infection rate of SARS-CoV-2 under natural ventilation in classrooms of a university in Beijing

Experimental and simulation methods are used to study the SARS-CoV-2 infection rate of students in classrooms of a university in Beijing. The Wells-Riley model is used to calculate and obtain that when the quantum generation rate (quanta) increases from 14 to 48, the infection rate of classroom personnel increases from 11.22% to 33.44% under window closing condition, and from 5.73% to 18.37% under window opening condition. The infection rate is 0.51% when the air change rate is increased to 12 h-1. Using the wearing mask model to calculate the infection rate, when the window is closed, the infection rate of inhaling the virus is 54.79% without a mask and 13.7% with a mask. When the window is open, the infection rate of inhaling the virus is 29.89% without a mask and 7.47% with a mask. In the case of short exposure, when the mask is worn, the infection rate is reduced to 23.41% under window closing condition and 15.45% under window opening condition, and the infection rate is reduced to 0.2% when the air change rate is increased to 5 h-1 by mechanical ventilation, which effectively reduces the infection rate.