5. (3 pts) A student with an active SARS-CoV-2 (Covid-19 coronavirus) infection walks into a classroom without a mask. Prior to the student entering the classroom, the air is free

from SARS-CoV-2 viral particles. The student is emitting 1,000,000 viral particles per hour. The classroom has a floor size of 8 m by 7 m, and a ceiling height of 3 m. Assume that there areno other sources of SARS-CoV-2 in the building, that the concentration of SARS-CoV-2 in the outdoor air is zero, and that there is no decay of the virus within the building. The air flow rate coming into the building (infiltration) and leaving the building (exfiltration) is 630m³/hour. a) Calculate the steady-state concentration of viral particles in the classroom if all conditions remain constant (viral particles/m³). b) Assume the viral particle concentration threshold for someone else in the room to catch Covid-19 is 200 viral particles per m³. How long would it take following the entry of the infected student for another student to catch the virus (in minutes)?