Comparison of estimated and self-reported basic reproduction number of common cold per day.

, person/day., person/day.Di is the assumed number of common cold infections in winter under different self-reported incidence rate, times. i indicates common cold incidence. i = 1, 2, 3. 1-common cold less than 6 times in the previous 12 months; 2-common cold 6-10 times; 3-comon cold more than 10 times. We assume D1 = 3; D2 = 6; D3 = 8.Oj is the occupancy level, person/room. j indicates occupancy level. j = 3, 4, 6. 3-three people per dorm room; 4-four people per dorm room; 6-six people per dorm room.Di,j is the proportion of students with different self-reported common cold incidences, %.M is the duration of a common cold, days. We assume M = 9 days [1].T is days in winter season, 120 days.Cj is the average CO2 concentration from 1:00 a.m. to 8:00 a.m. in rooms with different occupancy levels, ppm.fj is the re-breathed fraction of indoor air in rooms with different occupancy levels. fj = (Cj-C0)/Ca. Ca is the volume fraction of CO2 added to exhaled breath, 37000 ppm. C0 is the volume fraction of CO2 in outdoor air, 300 ppm.q is the quantum generation rate by an infected person, quanta/h. We assume q = 9 quanta/h [25].t is the time a infector remaining in the dorm room, hour/day. We assume t = 8 hours per day.