1/5 Modeling aerosols from an infector in different classroom scenarios. Here is one with instructor as super-emitter, emissions from speaking 50% of time, breathing, and coughing 7 times in a 75 minute lecture. Classroom = 100 m2 x 2.8 m ceiling w/ 34 students. #COVIDSchools 
2/5 Only particles w/ diam of 0.5 to 4 um considered. Multipliers of ASHRAE 62.1 classroom shown. 100% outdoor air supply. Top plot shows # particles from infector / m3 classroom air for various scenarios. ASHRAE, 1/2 ASHRAE, ASHRAE w/ a HEPA-based portable air cleaner.
3/5 Results show that in the under-ventilated classroom the concentration or infector-origin particles in air can exceed 1,000/m3 during a 75 min lecture. Red line shows results for a single student as emitter who only emits particles by breathing w/ appropriate distancing.
4/5 Bottom plot shows total particles of infector origin that are not just breathed in by each student, but that deposit in alveolar region (deep lung) in blue and (largely) the nose in orange (assumed nose breathing for respiratory deposition model).
5/5 This modeling (w/ large range of other scenarios) suggests a fair number of particles < 4 um may deposit in the deep lung w/ larger amounts in the head region during a 75 min lecture. Now if we just had viral loads resolved to carrier particle size & fraction infectious.
