Bridger Elementary School

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Bridger classrooms need more filtration capacity

Even with the Intellipure air purifiers running at their tolerable noise level (half speed):

✘ Classroom with the lowest airflow: Portable room P2

         1.2 air changes per hour*

With ventilation & filtration this low, how long do kids’ and staff’s viruses in their respiratory aerosols linger in room 107’s air?

>1 hour and 55 minutes

At 1.2 air changes/hour, 1 hour 55 minutes is how long it takes to clear out 90% of the respiratory aerosols being produced when kids and staff breathe, talk, sing, cough and sneeze. This 1.2 air changes per hour is also solely being provided by the Intellipure. The unit ventilator in room P2 is noted in the report as damaged by a fire and needing replacing.

✘ 8 more Bridger classrooms have less than 2 air changes per hour

At 2 air changes per hour, it takes the HVAC system and Intellipure 1 hour and 9 minutes to clear 90% of the respiratory aerosols.

Furthermore the HVAC system portion of the far too low ventilation rates in these 8 classrooms is solely from an exhaust fan. There is no air supplied to these classrooms by a proper HVAC system.

✘ 5 classrooms are between 2 and 3 air changes per hour & 7 more are between 3 and 6 – all below recommendations

Only 4 classrooms have safe air with ventilation and filtration providing 6 air changes per hour or more, clearing 90% of aerosols out in 23 minutes or less.

Room M104: 7.0
Room M107: 8.4 ***
Room P3: 7.1
Room P4: 7.0

***Good airflow:
Just 16 minutes to clear out 90% of aerosols in rooms M107

These four classrooms have good airflow, but they could be even better. At 12 air changes an hour, aerosols clear out by 90% in under 12 minutes.

About these ventilation and filtration measurements
Before resuming in-person learning in 2021, PPS had airflow testing conducted in every room of every PPS building. We have corrected gaps in Bridger’s airflow report as originally published by the district, to get this summary. We have also run numbers on one potential plan for Bridger adding Medify units that are being offered to schools by the Oregon Health Authority, if district personnel follow through on signing up to get them by April 28.

Bridger is one of the few schools
slated for an HVAC system overhaul …

Will PPS get it right?

Bond funding to revamp Bridger’s whole HVAC system is supposed to be starting work this summer (see page 17 of this presentation). But there have been serious delays from the plans for work the district has listed under the actual current 2020 bond mechanical systems upgrades page. As of April 2023, that page gives the original timeline planned by the district. Bridger was supposed to get it’s HVAC upgrade last summer. The district has also let kids and staff in Bridger just sit in these inadequately ventilated rooms for two years since the return to in-person learning, with an attitude that it doesn’t matter if kids are in rooms that have this little airflow.

We have seen no indication that the district will even seek a bare health-based minimum for how much ventilation Bridger kids and teachers will be provided from the new HVAC system. New HVAC systems are not required to be adequately ventilated for health – they are only required to meet minimal standards that reduce body odors to levels that don’t bother people.

That is why Safe Indoor Air For Oregon Schools supporters testified at the March 21 school board meeting that new buildings and an overhaul in an HVAC system needs to get new airflow measurements. You can’t manage what you don’t measure.

That is also why we want to see Bridger still get it’s fair share of Medify air purifiers. The Medify’s and the Intellipure’s will work on top of whatever the district does or does not accomplish for ventilation through Bridger’s new HVAC system, and if there are further delays, Bridger’s kids and Creative Science School kids moving to Bridger will still have protection from PM 2.5 that causes lung cancer and viruses that cause Covid, flu, and colds.

The Intellipure air purifiers are insufficient in Bridger classrooms

An Intellipure running at its tolerable noise level only provides 182 cubic feet of clean air per minute.  Even at its highest speed setting, which is too noisy, an Intellipure only provides 270 cubic feet of clean air per minute.

Bridger classrooms need additional, high quality air purifiers to provide safe air to kids now, when HVAC system overhauls will take the district years to do in all schools.

PPS staff need to order additional air purifiers for Bridger from the Oregon Health Authority by April 28

We did it! Thank you parents supporting safe indoor air! Thank you PPS and OHA staff and leaders!

The Oregon Health Authority first opened this program at the beginning of April, and at that time, PPS planned to order “no additional units.” But parents like you across our district organized with us to help district staff and leaders understand the need to take full advantage of this opportunity to obtain better air purifiers at no cost to PPS. The district announced initially that they would order only 600 units, but we have over 2600 classrooms in the district.

Parents in our network stepped up again, and our work paid off! PPS announced that they have placed an order for 3500 air purifiers.

We will see for sure how many of which models each school will get when the orders arrive, but we expect this to result in each classroom in the district either having two Medify air purifiers or one Intellipure and one Medify air purifier. And we hope the order will include the MA-1000s for gyms, cafeterias, large libraries, large music rooms and performance rooms, and other large communal spaces that serve students and staff. With both an Intellipure and a Medify, teachers can set the two air purifiers at a quiet speed, but still get more clean air delivered to the room than one Intellipure can deliver, even when it is set at it’s highest setting!

We’re not done working for cleaner classroom air, though. You can still join us below to learn more!

In our analysis that corrects gaps in PPS’s airflow report for Bridger, we have also analyzed one potential plan for adding Medify air purifiers from OHA.

Our analysis looks at what Medify’s would accomplish for ACH values across rooms at Bridger, if added to Bridger according to OHA’s guidelines from the webinar for this program.

See our full analysis and potential plan for Medify’s for Bridger here.

Highlights of our preliminary classification of providing Medify’s to Bridger using OHA’s suggestions for how to distribute them

Even if PPS’s planned HVAC overhaul continues to have major delays … Even if the HVAC overhaul fails to significantly improve airflow in Bridger … Medify’s in Bridger would clean the air today. And if PPS does improve Bridger’s airflow after upgrading the HVAC system, Medify’s will still make the rooms’ air even better.

3 Medify MA-50’s, 25 Medify MA-112’s, and 3 Medify MA-1000’s in Bridger’s current classrooms would:

  • Bring all 25 Bridger classrooms to above 3 air changes an hour
  • Bring the library up from 2.5 to 4.5 air changes per hour
  • Bring the cafeteria up to 2.4 and the gym up to 2.5 air changes an hour
  • Have classrooms ranging from 3 to 10.8 air changes per hour

When Oregon Health Authority announced their CDC-funded program to provide Oregon schools with free HEPA filters from Medify, our group of parents and community members supporting Safe Indoor Air For Oregon Schools were right in the middle of a push for PPS to budget for adding highly effective, whisper quiet, inexpensive air purifiers to classrooms that do not have the level of airflow we need. Units we were advocating for included Tower of Power (480 cubic feet of clean air per minute at a noise level you can barely hear) and the Owl Air (556 cubic feet of clean air per minute, also at a quiet noise level).

Medify’s do not have quite the high impact clean air delivery rate at such quiet levels as do the Tower of Power and Owl Air filters we demonstrated at the March 21 PPS school board meeting, but Medify’s are decent. Medify MA-112 – which OHA is offering for classrooms – provides 280 cubic feet of clean air per minute at a noise level that won’t distract from teaching in the classroom.

Medify MA-1000’s are being offered for our extra large school spaces. The MA-1000 units can add 1000 cubic feet of clean air per minute to school spaces that can sustain the noise they make at their highest speed setting. At Bridger, that would include the cafeteria and the gym. If set at their quiet speed setting, the Medify MA-1000’s can also provide 565 cubic feet per minute to other large rooms. OHA is also offering Medify MA-50’s for small spaces like offices, nurse’s office, and conference rooms.

Adding Medify’s on top of the Intellipures would add substantial and much needed filtration capacity to Bridger and other elementary through 8th grade schools. At minimum, we need one additional air purifier for all 597* elementary, middle school, and K-8 classrooms which are below 3 air changes per hour and all 1111* kindergarten through 8th grade classrooms that get between 3 and 6 air changes per hour.

Join us in asking PPS and OHA to add these new filters while also maintaining the existing filtration capacity the Intellipures provide.

How can you help?

We need to make sure PPS and OHA provide more air purifiers to Bridger – Sign up to help advocate for PPS ordering these units and OHA granting them!

Let’s get more air filtration in the 14 Bridger classrooms that do not even get 3 changes of air per hour and the 7 classrooms that only get between 3 and 6! And let’s make sure Bridger’s cafeteria, where kids pack in close to eat lunch, and library and other key spaces get better air quality.

Join us to be part of a group of parents and community members advocating for strategic, effective, and science-based planning for sufficient ventilation and filtration capacity in PPS schools — including Bridger.

Sign up on our signup form to also help make a better proposed plan for Bridger. Facilities staff worked hard to get the Intellipures, but PPS left serious gaps in the ventilation and filtration in elementary, middle school, and K-8 schools across the district.

So we would like participation and feedback from more PPS community members – parents, family, and actual staff in our schools – on what spaces in each school are actually used for what, so that PPS kids and staff, including kids and staff at Bridger, get more of the quiet, effective filtration capacity that they need. Sign up below to join our organizing for PPS air quality!

*Notes on our numbers

Air changes per hour given here are “equivalent” and include ventilation and filtration.  These numbers are based on the district’s airflow report for Bridger, conducted in August 2021 (available at but corrected using specifications from the manufacturer of the Intellipure units to allow calculation of air changes per hour with the Intellipure at half speed instead of the district-provided air changes per hour with the Intellipure set at full speed.

Also, please note that the total classrooms across the district below 3 and between 3 and 6 are 597 / 1111 and counting…