2019 Yes https://www.tandfonline.com/doi/full/10.1080/10962247.2019.1629362 Kaduwela, Ajith P. North America Exposure Study Middle/Jr High (6-8) Temperature Humidity Carbon Dioxide (CO2) Particulate Matter (PM) The particulate level in the classroom was low until a distant wildfire advected large amount of particulate matter to the San Francisco Bay Area. Very high (10–15 times compared to the background) particle numbers (per m3 of particles with diameter >0.3 μm) were observed in the classroom during the wildfire.These particles were relatively small (0.3–1.0 μm) and the filters (MERV 8) of the ventilation system were unable to filter them out. The particle number was independent of the occupation before and during the wildfire suggesting that all observed particles were infiltrated into the classroom from outside. Consistent with previous studies, no appreciable increase in the local ambient CO2 background was observed during this distant wildfire event.