Thread by @CorsIAQ

1/ Some slides from a previous talk I gave on indoor air quality in K-8 classrooms in Texas.

Slide A. Impacts of ventilation on students in K-12 classrooms. Note past studies on health, absenteeism, and performance. Also note image to right w/ idling bus & intakes.

2/ Slide B. Cumulative distribution functions for average and peak occupied day carbon dioxide concentrations in 115 classrooms. Note that 20% of classrooms w/ average CO2 > 2,000 ppm and peak > 3,000 ppm.

3/ A large fraction of classrooms did not come anywhere close to ASHRAE standard 62.1, and this was often intentional, with schools reducing outdoor air intake via dampers or attempts to actually seal over intakes on units on portables. Under-resourced schools saving energy.

4/ For traditional student # and area of conventional classrooms ASHRAE 62.1 2019 yields air exchange rates of around 3/hr (give or take a bit). We found many classrooms operating with air exchange rate of less than 50% (even < 30%) of ASHRAE 62.1.

5/ Slide C. In a survey of over 800 teachers, 44% complained about odors in their classrooms (worst across board = body odors), an indication of very poor ventilation. 36% said that the odors affect their work.

6/ Slide D. In response to odors, teachers noted that they use spray and plug-in air fresheners, and scented candles (not allowed in schools but used anyway). So, poor ventilation leads to increased volatile organic compounds (VOCs), particulate matter, ....

7/ and monoterpenes and sesquiterpenes used as scenting agents & that react with ozone resulting in secondary organic aerosols & other oxidized products.

And we have not even gotten to increased airborne infectious disease transmission yet!

8/ A few other important notes on slides. About 1 in 5 classrooms had carpet when this study was done. 1 in 5 teachers used pesticides in their classrooms, even though this was expressly forbidden in Texas. Not a lot of oversight or help.

9/ At the time the State of Texas had something like 3 employees who oversaw indoor air quality problems in public buildings, including schools across entire State. Not sure whether that has changed. So, under-resourced and poorly-ventilated schools without much State help.

10/ I submit based on recent experience that the situation has not changed all that much, although some school districts do much better than others.

And I should have added .... is it surprising that school districts have difficulty trying to implement layered risk reduction strategies to protect against exposure to SARS-CoV-2?