Updated 3/29 to include independent analysis by D.S. O’Connor & Associates.
The following documents are the most recent Indoor Air Quality Reports of the Haverhill Public Schools conducted by TRC and an independent analysis of the results by Sarah Gibson of D.S. O’Connor and Associates. Testing was completed to determine whether or not classrooms have sufficient ventilation and/or filtration to safely operate the buildings at hybrid capacity with physical distancing at a minimum of 6 feet. It is unknown what conclusions can be drawn in regard to increased capacity (if any). The Association has requested the District explain its assumption that the buildings have adequate air flow and ventilation to accommodate more students without increasing the risk of spreading the coronavirus through the air.
With help from the MTA, the Haverhill Education Association has obtained an independent analysis of the TRC report, which was shared with the District on March 25th, 2021:
14 Memo re COVID 3-18-21.docx
I am writing to follow up on our meeting on 3/18/21, in which we discussed the indoor air quality report dated 3/10/21 from TRC. Some of the information in this email repeats what I have already sent to you, but I wanted to try to put all of what we discussed in one place. My apologies for the length of the message.
TRC measured carbon dioxide (CO2), carbon monoxide (CO), temperature, relative humidity (RH), total volatile organic compounds (TVOCs), and particulate of 10 microns or larger (PM10). These are typical indoor air quality parameters. They provide limited information on how well the ventilation systems in Haverhill school buildings can contribute to a reduction in the risk of COVID transmission.
As we discussed in our meeting, guidance from the CDC and many other entities stress a layered approach to COVID prevention: wearing masks, staying distant from other people, and increasing ventilation. One of the primary means of reducing COVID transmission risks with ventilation is dilution – i.e., increasing the amount of outdoor air as much as possible. This means opening fresh air dampers as much as possible, and/or running ventilation systems for as long as possible during the school day, and/or opening windows whenever possible. Guidance from the Harvard School of Public Health (HSPH) and American Industrial Hygiene Association (AIHA) recommend that ventilation systems achieve 4-5 air changes per hour (ACH), based on the following formula:
Cubic feet per minute (cfm) of outdoor air x 60 minutes / volume of room
However, the calculation of ACH requires measuring the outdoor air supply volume, and measuring the dimensions of rooms. TRC did not do either of those measurements.
Instead, TRC appears to be relying on measuring CO2 as a proxy for gauging the adequacy of dilution ventilation in selected spaces in each school building. TRC cited Standard 62.1 2016 from the American Society of Heating, Refrigeration, and Air-conditioning Engineers (ASHRAE), which recommends that indoor CO2 levels do not exceed outdoor CO2 levels by more than 700 parts per million (ppm). TRC also cited guidance from the Mass. Dept. of Public Health (DPH), which recommends that CO2 levels in schools not exceed 800 ppm, with 600 ppm preferred. Both ASHRAE Standard 62.1 and DPH’s CO2 guidance are pre-COVID guidance. The DPH guidance is available at Mass. Dept. of Public Health, Carbon Dioxide and its Use in Evaluated Adequacy of Ventilation in Buildings, document available from list at https://www.mass.gov/lists/indoor-air-quality-manual-and-appendices. TRC did not measure outdoor CO2 levels, and estimated that they were approximately 400 ppm.
TRC provides a summary of the building-wide average CO2 measurements in each school on page 5 of its report. At first glance this may be reassuring, since none of the building averages exceeds DPH’s recommendation of 800 ppm. However, the CO2 measurements in each individual building are less comforting. In many buildings – Bartlett, Bradford, Consentino, Golden Hill, Hunking, Whittier, Pentucket Lake, Tilton Lower, Tilton Upper, and Walnut Square – CO2 levels exceeded DPH recommended levels in at least one location. At the time of the measurements, all buildings were only partially occupied because the school district has been following a hybrid learning model. Although there were fewer than normal occupants in the rooms in which measurements were taken, in Bartlett, Hunking, and Tilton Lower, almost a quarter of the rooms selected exhibited CO2 levels in excess of what DPH recommends.
There are measures that will increase outdoor air or its equivalent, some of which I mentioned above. In addition to opening dampers, running ventilation systems for extended hours, or opening windows, school districts can explore whether improving filtration in HVAC systems is an option. Guidance from HSPH and ASHRAE indicates that if MERV 13 filters can be used, the filters are capable of screening out about 80% of airborne virus particles. This can result in a significant increase in “clean” air, and thus, an increase in dilution and the reduction of risk of COVID transmission.
In addition to improving filters, HEPA filter portable air cleaner units can also add substantially to the reduction of risk of COVID transmission, because HEPA filters are 99% effective at screening out virus particles. As the units draw air in, pass it through HEPA filters, and emit the cleaned air into an occupied space, they are producing the equivalent of outdoor air.
One additional topic we discussed is the importance of having a full understanding of the ventilation in nurses’ offices. ASHRAE has generated guidance for nurses’ offices in schools that recommends the following:
Nurses office and isolation room should have Normal and Isolation ventilation modes. Among other recommendations, in isolation mode, the ventilation should be capable of providing the following:
Air Changes per Hour = 10
Exhaust directly to outdoors
No air re-circulation
All should be under negative pressure.
If retrofits to existing ventilation systems are not possible, ASHRAE recommends that school districts should set up temporary nurse’s stations in trailers.
American Society of Heating, Refrigeration and Air-conditioning Engineers, Reopening of Schools and Universities, https://www.ashrae.org/technical-resources/reopening-of-schools-and-universities, 7/22/20. See section on Nurses’ Offices.
In our meeting, we discussed some questions the HEA might ask to follow up on TRC’s report:
- How were rooms selected at each school for TRC’s testing?
- Will there be a second round of CO2 testing once the district has transitioned to full time in-person learning (i.e., full occupancy)?
- What is the MERV rating of filters in all school buildings? Can filters be improved in any locations without adversely affecting the operation of the ventilation systems?
- Are HEPA filtered portable air cleaning units being used in rooms where MERV 13 filters are not an option, or where TRC’s report showed elevated CO2 levels? What are the specs for those units – i.e., how much clean air do they put out?
- What is the district’s plan for meal times when students cannot wear masks?
- Have assessments been done of the ventilation in nurses’ offices and medical waiting rooms in school buildings? If not, is the district planning to conduct those assessments?
With regard to the HEPA filter portable air cleaning units: if you can get the specs to me (or even the manufacturer and model number), I can let you know how many ACH equivalents the units are capable of providing.
I hope this is helpful to you. Please let me know if you have any questions.
Sarah Gibson, Esq., MS Work Environment
D.S. O’Connor & Associates, PC
639 Granite St. Suite 305
Braintree, MA. 02184
Download Summary of Results March 10, 2021
Download 418020 Haverhill Public Schools 2021 IAQ Screening Assmt Report