Evaluation of infection risk for SARS-CoV-2 transmission on university campuses

In 2021, COVID-19 has been widely spread worldwide. Few studies focused on infection risk in the different confined spaces on university campuses. However, obtaining the quanta value of SARS-CoV-2 using the conventional method is not identical. Therefore, in our study, the estimation method of the quanta value was improved via statistically analyzing the viral load of the infectors and fitting the droplet number concentration of different particle sizes. Moreover, the infection risk and efficacy of typical engineering control measures in confined spaces such as dormitories, classrooms, gyms, libraries, and refectories were evaluated using the improved Wells-Riley equation. The results demonstrated that: (1) the quanta value range of SARS-CoV-2 was 20.49 ∼ 454.87 quanta/h, which was confirmed by the existing literature; (2) the infection risk in dormitories and classrooms was 100% (exposure time was eight hours) and 5% (exposure time was 1.5 h), respectively, while basic reproduction numbers were both 2.8; (3) The combined control measures mainly based on engineering measures such as ventilation, high efficiency particle air (HEPA) filter, ultraviolet germicidal irradiation (UVGI), partially based on surgical masks were recommended. The findings could provide suggestions for universities to scientifically formulate intervention measures and self-protection means for students.