Here are the steps we've done and criteria we established to ensure the healthiest environment possible:
- We have invested significant time and energy in improving our HVAC systems over the last year.
- Our classrooms used to be fitted with Merv 8 filters which blocked particles in the 3-10 µm range but now all classroom filters have been upgraded with Merv 13 filters that block particles down to .3-1.0 µm.
- We have upgraded our classroom HVAC equipment with needlepoint bipolar ionization devices that have shown significant efficacy on improved filtration of smoke born particles which will make our existing filtration even more effective at dealing with smoke in the air.
- In addition to our mechanical HVAC system upgrades, all classrooms have an additional portable HEPA filter capable of providing an added filtration of particles smaller than .3µm.
- PAUSD has shifted from a 6-month filter change out schedule to a 3-4 month replacement schedule.
- There are essentially two components of the HVAC system: Fresh air (ventilation) and recirculated, filtered air (filtration). The current guidelines are to increase outside air to dilute the interior air (ventilation) and install new, clean filters (filtration). The guidelines prefer using MERV-13 air filters if the units can handle them but recognize many older units may only be able to use a MERV-8. The guidelines do not require the filter upgrade because many older hvac units cannot function effectively with a MERV-13 filter because they create too much of a pressure drop. That was the target we met previously strove for. You can think of it like breathing through your cloth mask is like the units equipped with a MERV-8 filter that the units were designed for but breathing through 10 masks stacked up would be the MERV-13. That is just an example of the pressure drop and airflow to help understand.
- We continued to work to improve the air ventilation and filtration and have set up new classroom guidelines that we are using to certify the classrooms.
- The first guideline is filtration. We have done extensive research and have found high performing, low pressure drop MERV-13 filters that will work in our older units. Back to the mask example, that is like wearing an N95 mask instead of a cloth mask. We have replaced all filters in the District with MERV-13. This includes custom ordering and modifying some older units to work with the MERV-13 filters. Our new guideline is that every room must have MERV-13 equivalent filtration as a baseline.
- Our second guideline is ventilation. We established a baseline of measuring double the code required fresh air per occupant of 15 CFM (cubic feet per minute) of air per occupant. There are a number of ways the code allows that number to decrease in order to save energy but we are disabling those features to provide a baseline of continuous 30 CFM per occupant. In many cases we will have more than that depending on the age and design of the system but we are setting that as a baseline. Additionally, opening windows will increase that.
- We then test the rooms. This is a simple pass/fail test. If it meets those two criteria, MERV-13 and 30 CFM, in gets certified. If it does not meet those criteria then we put a portable filter in the room. All portable filter rooms will also be certified under the portable filter option of our certification.
- We also are putting portable filters in rooms that we do not have time to test. We will continue to work through the District and test the units. When we test a room, if it passes, we will pull the portable unit out of the room and re-certify it as passing with mechanical ventilation. If a room fails, that does not mean the system does not work. Sometimes it can be a 5-minute fix. Other times it could be a 5-hour fix. And yet other times it could require a part that has to be ordered.
- We are additionally doing air quality testing to further enhance the systems as a third round of continued efforts to improve the effectiveness of the classrooms ventilation and filtration. This is the needlepoint bipolar ionization that we have presented briefly in past board meetings. Based on our test results, we are confident on going forward with the new technology and have been doing test installs to determine their effectiveness and compatibility with our District technology. The purchase of the needlepoint bipolar ionization units will go before the Board on December 15, 2020 for their review and direction.
The best way we've heard this explained is to imagine a swimming pool. The ventilation is a garden hose filling the pool. The filtration is the pool cleaning system. COVID is a child peeing in the pool. You would like to filter that water to clean it up but your filter can only do so much so you also need to keep adding fresh water. The more fresh water you have, the more diluted that pee is. So we are trying to both add water and upgrade our filtration.