All posts by rstuartcih

Ralph graduated from Cornell University in 1979 and got his master's at the University of Vermont in 1989. He managed lab safety at UVM for 25 years and was most recently the Chemical Hygiene Officer at Cornell for 3 years. His professional contributions include developing electronic information resources for the laboratory safety community; participating in a lab waste regulatory reinvention project with the U.S. EPA; and developing a laboratory ventilation program at Cornell. He served on the American Chemical Society Division of Chemical Health and Safety (Links to an external site.)

KSC Ventilation Questions for Spring 2021

  1. Do we expect similar classroom occupancies in Spring 2021 as is Fall, 2020 or will the College be encouraging more student time in the classroom this spring and/or higher classroom occupancies?
  2. Are the ventilation bands below appropriate in terms of observed air changes per hour? (The classifications are based both on the average ACH and the percent variation around this number.)

    Of possible interest, the ad hoc group of scientists behind the spreadsheet at https://tinyurl.com/covid-estimator suggests that about 5 air changes per hour is standard for university classroom. See rows 193 – 300 for their discussion of this number. A less technical description of this resource can be found in this National Geographic story.
  3. Should we adjust the classroom schedule based on ventilation category of the room? For example, should 2 hours of clearance time be required after a class in a low ventilation room; 1 hour for a medium ventilated room; and 15 minutes for well ventilated rooms?

    The Registrar’s Office has indicated a willingness to work with such guidelines if they are received by December 11. They have already rescheduled classes away from Blake 101 to address this concern. Other buildings of high concern in this regard are Joslin and Morrison, because they rely on natural ventilation for air exchange.
  4. Does providing HEPA filters impact the ventilation category of classrooms and scheduling of classes? Which buildings or rooms should be prioritized for placement of additional cleaners?

    For the fall semester, we deployed 100 air cleaners with HEPA filters in locations where there are higher risk activities. We have put multiple cleaners in classrooms to have as much impact as possible as possible. The role of CADR in covid risk assessment for ventilation purposes is discussed at the spreadsheet referenced above. We have 50 more air cleaners on hand for to deploy for the spring semester.

    Background information on the room air filters: The room air filter size is described by the clean air delivery rate (CADR) which describes the size of the room that the filter is designed to clean. Our filters have a CADR of 100 to 200 square feet. For comparison, our classrooms tend to be between 500 and 800 square feet.
  5. What emerging technologies should KSC implement to supplement physical distancing and optimizing ventilation in classroom? Candidate technologies include ion generators, airborne hydrogen peroxide dispersal systems, and space humidification.
  6. Question from the Music Department:
    Should the singing schedule in the Redfern Alumni Recital Hall be adjusted? Right now they are singing for 30 minutes with a 20 minute break for air exchange. Can they keep singing for an entire class of 1 hour 45 minutes without a break and be safe with the current air exchange? The Music Department’s covid management plan can be downloaded here.

Current KSC Room Air Exchange Data

The assessment data in the table is based on the method Ralph developed at Cornell and which is described in this article in the Journal of Chemical Health and Safety.

CO2 data in 201 Science Center

Average Vent rate9.40
Std Deviation1.92
% Std Dev20%

Fog VOC data in 201

Average Vent rate4.22
Std Deviation1.64
% Std Dev39%

CO2 Data in 301

Average Vent rate6.35
Std Deviation0.88
% Std Dev14%

KSC Classroom Building Ventilation Roster

KSC Classroom Building Ventilation Assessments

BuildingRoomVentilation RateVentilation Group Sampling dateRel Humidity
Blake 101 1.6 +/- 17% Low ventilation October 30, 202028%
Blake 101 1.8 +/- 4% Low ventilation October 30, 202028%
Huntress 105 5 +/- 14% Medium ventilation November 2, 202026%
Huntress 109 6 +/- 20% Medium ventilation November 2, 202026%
Joslin 103 17 +/- 26% Well ventilated November 6, 202032%
Joslin 103 4.3 +/- 11% Medium ventilation November 6, 202032%
Living Learning 129 3.7 +/- 10% Medium ventilation November 5, 202032%
Media Arts 155 3.7 +/- 12% Medium ventilation November 5, 202033%
Morrison 202 5 +/- 14% Medium ventilation November 2, 202024%
Morrison 201 4.4 +/- 40% Low ventilation November 2, 202024%
Parker 311 7.8 +/- 12% Well ventilated November 5, 202035%
Redfern 118 7.5 +/- 10% Well ventilated November 6, 202025%
Redfern Recital Hall 1.5 +/- 20% Well ventilated December 9, 202020%
Redfern Main theater 3 +/- 10% Medium ventilation December 9, 202020%
Science Center 201 9.4 +/- 20% Well ventilated November 24, 202020%

Questions about this information should be directed to Ralph Stuart at ralph.stuart@keene.edu

Ventilation Assessment References