1/ Our team @ut_caee just completed a 4 yr study of indoor air quality in high schools (46 classrooms in 7 high schools) w/ 4-day measurements completed multiple times/classroom. T, RH, CO2, PM10, PM2.5, PM1, speciated VOCs, formaldehyde, mold (surfaces/air), pesticides .... 
2/ phthalates, ozone, lighting, and a lot of valuable metadata. Overwhelmed w/ data but starting to push some pubs out. The plot in (1) is of PM10 concentration in one classroom (& outdoors as light shading) over 3 days & is similar in spike trend to almost all classrooms.
3/ Peaks correspond to re-suspension of particles when students enter and exit the classroom, most from floor and likely a small amount from desks and clothing. The Right-most (evening) spikes occur at roughly the time of custodial activity ....
4/ Can deposited particles that contain infectious viruses that are not yet inactivated pose an inhalation risk when re-suspended from the floor? Note that these measurements were not near floor, but at breathing zone level for someone sitting.
5/ Our paper in Building and Environment also clearly shows higher PM concentrations in classrooms w/ carpet as opposed to vinyl composite tile (a phthalate source). Should remaining carpet be replaced w/ hard surface floors in schools? Also easier to damp mop and disinfect.
