Hayhurst is getting a second portable air purifier in each classroom

Why is a second air purifier needed? Is it enough?

Before resuming in-person learning in 2021, PPS measured ventilation in every room of every building. The district’s data shows that Hayhurst has terrible ventilation rates. In 15 of out 22 Hayhurst classrooms, the HVAC system does not even provide one single change of air in an hour. The district’s installation of MERV 13 central air filters did nothing to improve these rates in Hayhurst classrooms, and even if the Intellipure air purifiers the district purchased for each classroom are run at their tolerable noise level (half speed), these classrooms still only get two air changes per hour at most.

Hayhurst’s classrooms fall far short of health-based recommendations for fresh, clean air. Hayhurst needs more filtration capacity to clean the air of respiratory aerosols and indoor pollutants. When we clean indoor air properly, kids and teachers enjoy fewer respiratory viruses, decreased allergy symptoms, less asthma attacks, fewer headaches and fatigue, better concentration, better test scores, and better attendance.

Now, thanks to the amazing advocacy of parents who have joined us, every PPS classroom is getting a second air purifier – for free! The new free air purifier is a Medify MA-112, and is coming from a CDC-funded program through the Oregon Health Authority.

Use our interactive map to see why it is important that Hayhurst classrooms run two air purifiers – and whether even more are needed

Frequently asked questions about ventilation and air purifiers in PPS

More answers to questions about the district’s work on ventilation, the Intellipure air purifiers, and the new Medify air purifiers that are being added.

Why aren’t the Intellipures the district already obtained enough for Hayhurst classrooms, and how did SIAFOS supporters advocate for additional air purifiers?

Like many schools in the district, the district’s findings on airflow in Hayhurst were particularly bad. Ventilation in most Hayhurst classrooms, offices, and other spaces is far below health-based recommendations for how much clean, fresh air kids and staff need. 16 classrooms do not reach even 3 changes of air per hour, and 5 more only get between 3 and 6 – even if the Intellipures are running at their tolerable noise level of half speed.

The Intellipure air purifiers provide an improvement to the poor ventilation from the HVAC system in Hayhurst classrooms, but the Intellipures are insufficient. 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. If all of Hayhurst’s Intellipures are running at half speed, 13 of Hayhurst’s 15 classrooms with particularly bad ventilation still do not reach 2 changes of air an hour, and two of those 15 classrooms only get 2 changes of air an hour. At 2 changes of air an hour, it takes the HVAC system and the half-speed Intellipure 1 hour and 9 minutes to clear out 90% of the kids’ respiratory aerosols. Kids and staff viruses linger in classroom air for over an hour in these classrooms.

This is why we worked with parents across the district last spring to advocate that PPS classrooms, including those at Hayhurst, 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. Just as we were advocating to the school board for the need for additional filtration capacity in PPS classrooms, the Oregon Health Authority announced a program offering free Medify air purifiers to any K-12 schools in Oregon. When it became clear that district staff were not planning to sign up for any of the free air purifiers from OHA, we made the case for why Hayhurst needed these new units. Parents from across the district joined SIAFOS in advocating that the district take full advantage of the program.

What about the district’s upgrade of building air filters from MERV 8 to MERV 13? Isn’t that providing enough improvement in filtration through the HVAC system at the building level?

Upgrading building filters to MERV 13’s was an important step we are very thankful the district invested in. Over 1300 elementary, middle school, and K-8 classrooms did get a filtration benefit from this upgrade, and numerous high school classrooms also benefited (we have not yet analyzed high schools fully to know exactly how many and which high school classrooms derived a benefit as we have for the lower grades).

However, this upgrade has provided no benefit for preventing respiratory infections in Hayhurst classrooms. Hayhurst classrooms do not have any recirculating airflow through the HVAC system — 100% of the little airflow Hayhurst classrooms get from the HVAC system is outdoor air. So MERV 13 filters will be helpful to Hayhurst classrooms during wildfires, but the MERV 13 filters in the Hayhurst HVAC system do nothing to prevent the spread of viruses in these rooms, and they do not help to clean classroom air from aerosols and pollutants generated indoors.

Why two or more filters per classroom / office / learning space?

SIAFOS is a partner / affiliate organization of a national group – Indoor Air Care Advocates – which has developed this helpful graphic and explanation for another reason multiple air purifiers are so important in schools across the nation that have poor ventilation. Note that for many PPS rooms, three or even four air purifiers will actually be necessary to reach health-based recommendations of at least 6 air changes per hour and keep noise levels from the units low enough for the classroom’s needs.

What settings should be used on the air purifiers?


Fan speed setting we expect to work in most classrooms: Half speed

At half speed, one Intellipure cleans 182 cubic feet of classroom air per minute.

DFS: Off

At this point in time, we are recommending DFS be off because it appears to be a type of ionization / additive air cleaning technology.


Fan speed setting we expect to work in most classrooms: Speed 2

At fan speed 2, one MA-112 unit cleans 281 cubic feet of classroom air per minute.

Speed setting note: If your classroom can handle a higher speed than 2 on the Medify and half speed on the Intellipure, you will get even more air cleaning done, but noise levels will be higher. Likewise, lower levels get less air clearning. Email us at info@safeairoregon.org or fill out our Google form if your classrooms’ units are running at lower or higher speeds, and you would like details on what level of air purification that is providing.

Ionization: Off

Please leave the ionization setting off. Ionization is off on the Medify unit by default.

Additive air cleaning note: Aerosol engineers and indoor air quality scientists widely agree that ionization / additive air cleaning technologies are not recommended for classrooms.

We think the Intellipure or Medify in our classroom has not had a filter changed this entire time in the past 2+ years. And/or the Intellipure in our classroom has a “red light of doom” on.
Why are we getting new air purifiers if the existing ones aren’t being maintained?
How are filters supposed to get changed? Has the filter truly not been changed on our classroom Intellipure?
Is it a fire hazard to run it with one of the “red lights of doom” on?

We are still working to understand the process the district has intended to follow for air purifier filter changes for the past two years. The district is not forthcoming with this kind of information. Teachers have indicated that adequate staffing and funding for building custodians is critical to this kind of equipment maintenance, and may be a reason for filters not getting changed. However, there also seems to be widespread confusion among staff and the public about filter changes — for example, if Intellipures have been running for school days only, then their filters have not needed a change yet.

In addition, the OHA program is now supplying 5 years worth of replacement filters for Intellipures as well as Medify units. So supplies should be in place for filter changes to be possible.

While the district is not very transparent about PPS’s process for filter changes over the last two years, the manufacturer’s are clear on how filter changes are supposed to operate. Some of the confusion filter changes among PSS staff seems related to the filter change indicator lights on the units. As stated above, Intellipure air purifiers have likely not been running long enough yet to need any filter changes. However, the units do need occasional vacuuming and that has likely been a need since their purchase in 2021. In addition, if there is a red light on for filters 1, 2 or 3, those are not in fact indicating any sort of doom, and do not present a fire hazard. If the air purifier in your classroom is turned off because a red light is on, please reach out for us to help troubleshoot, and read here for more about what different red lights on the district’s air purifiers mean.

Why improve air quality to 6 to 12 air changes per hour?

Better air quality improves health! Kids and teachers enjoy improved respiratory health – including fewer respiratory viruses, such as colds, covid, and flu; decreased wheezing, dry coughs, and rhinitis; decreased allergy symptoms; fewer asthma attacks; decreased asthma rates; and fewer headaches and fatigue.

Better air quality improves attendance! Ventilation and airflow at health-based recommendations reduces kids’ absences, reduces visits to the school nurse for all of the above respiratory health issues, and results in fewer teachers and staff needing to take sick leave.

Better air quality improves performance and grades! Ventilation and airflow at health-based recommendations increases attention, concentration, and cognitive performance, and decreases errors among students and staff. Kids in schools and classrooms that have more air filtration and better ventilation get better test scores and higher grades. Air quality addresses core needs we have to make up for learning loss our kids are still recovering from!


Many thanks to Indoor Air Care Advocates for providing key FAQ material on indoor air quality in classrooms that we adapted for Oregon and PPS. And to Laura Mertens for CR box image.