Thread by @CorsIAQ

1/ Enjoyed my recent Ask an Expert segment with @BungerKCBSRadio.

radio.com/kcbsradio/news…

Some highlights. Schools in US (in general) have been woefully under-ventilated even before COVID-19.

2/ Increase ventilation. Combine use of outdoor air supply & portable HEPA filtration to yield > 6/hr air change rate. For schools w/ mechanical systems, open outside air dampers and disable demand-control ventilation if it exists.

3/ It is important to flush out those classrooms even when students and teachers are out of them for some time.

4/ For schools w/o mechanical ventilation but w/ operable windows ... open two windows as far apart as possible & w/ cross flow (often possible in portables). Place a fan on high setting w/ inward flow in one window & second w/ slightly lower setting w/ outward flow.

5/ Make use of portable HEPA air filtration systems that are properly-sized. A unit w/ CADR = 300 scfm in a standard sized K-8 classroom can often yield 3 to 3.5 equivalent air changes per hour.

6/ This can lead to inhalation dose reductions of 50 to 70% (or more) for classrooms that are already under-ventilated (more than 80% of classrooms we have studied in Texas do not meet ASHRAE 62.1 standards), or for where additional ventilation is difficult.

7/ The costs for portable HEPA filtration systems that yield good inhalation dose reduction are small when broken down to the student level -- just over two Grande Frappuccinos per year (not day, week, or month). Repeat PER YEAR. Children are worth the investment. See below.