Still Working On Filtration Units

Ontario School Safety is still working hard to try to get CR boxes allowed in classrooms. 

They donated some directly to the local board office. Unfortunately (and unsurprisingly), they can't be used without these following six questions answered, so they crowdsourced for studies. Here are some of the answers they got - in case others need them - and some links I found myself. (The letter-writer that responded to them appears unfamiliar with question marks.)

1. In relation to CADR, is it possible to obtain manufacturers data ideally showing the fan curve air volume (at low speed) vs static pressure and similarly the MERV-13 filter pressure drop data, again air volume vs static pressure curves.

I couldn't find a study that specifically referenced fan curve air volume vs static pressure, but I did find...

• A peer-reviewed study published in, Aerosol Science and Technology, in January 2022 says, "Overall, our results demonstrate that our Corsi-Rosenthal air cleaner efficiently reduces suspended particle concentrations in indoor environments." Their units removed more particles than HEPAs, but I'm not sure it really matters since HEPAs are also being removed by this board! They're putting all their eggs in one basket: mechanical ventilation. Gone are the days of layers of protection with filtration units or masks. But here it is anyway:
  
• This graph shows that CR boxes are less money, have less power draw, and are quieter than HEPAs.

  
• More stats and charts are here, from Jim Rosenthal's article, February 2022. 
• Finally, Richard Corsi wrote a thread to address school board concerns of the units overheating or otherwise posing a hazard, where he also directly addresses the pressure drop and resistance on the fan motor. 

2. Can you send us literature from the fan manufacturer or their agent indicating approval for use as a CR box portable air cleaner or similar connected system.

 Dr. James Smith replied, "Lasko, the box fan company, has activity participated in developing and shipping DIY filter kids with their box fans. . . . So, yes, they approve."

3. Do you have information from the filter manufacturer on their recommended filter use, including the use of filters with an exposed arrangement such as that of the air cleaners donated by OSS.

Lazarus Long said, "3M makes the filters. Let me know if your manufacturer question is not answered here:" pointing to when, in February 2022, 3M said, "This DIY movement caught the eye of 3M scientists and, after testing, the results are clear: the CorsiRosenthalBox works! Thank you @JimRosenthal4 and @CorsIAQ for your relentless advocacy for clean indoor air."    

4. Can you also provide literature on the anticipated MERV-13 filter changes including method to change the filters and schedule for the filter changes.

Jim Rosenthal did some tests using 5-month old filters, and found they continued to provide excellent results. He recommends, "In a classroom, if the CR boxes are only run when students and/or teachers are present, 6-10 months between filter changes would be OK. . . . In my opinion, the biggest mistake people make is that they change the filters too soon." As for the method, it does require disassembly and reassembly each summer. The fact that there are volunteers prepared to make and donate them, you're likely to find they're also willing to come in every June to change the filters. I know I would have been happy to do that if only they were allowed. 

5. Have you or your group come across details that you can share from Public Health Ontario or equivalent, related to the use of exposed filtration media and infectious diseases, ideally in a public non medical setting / potentially accessible to children.

Public Health Ontario wrote, in July 2022, about the importance of filtration unit as another layer of protection, and specifically that "filters with a minimum efficiency reporting value (MERV) greater than or equal to 13 are efficient at capturing particles . . . can remove 85% of particles. . . . A portable air cleaner that relies on mechanical filtration alone to remove particles from the air is least likely to pose other hazards. . . . The use of portable air cleaners to complement existing HVAC filtration and ventilation can be considered in settings such as schools. . . . Some DIY air cleaners [CR boxes] were able to achieve similar CADR estimates due to the greater air flow across the MERV 13 filters . . . they appear to work well with proper construction and materials." 

6. Do you know of other school boards in Ontario or elsewhere in Canada that are currently using CR box air cleaners.

In an Education Forum article of November 2022, published by OSSTF, they said, "By September 2021, our Teacher/Occasional Teacher Bargaining Unit in District 6B (Superior North) obtained the school board's permission to incorporate CR Boxes into our courses as Rich Learning Tasks." In Québec, the Pierre Elliott Trudeau Elementary School had all grade 5 and 6 classes make purifiers for the entire school. 

And here's a BONUS study: RCT evidence for air cleaning reducing student absence from school. It's from the UK, so it might not count in their eye, but, seriously, air is air. Clean air means fewer absences. It's not flippin' rocket science! 

Every day that the board finds another way to delay or deny air filtration in the classrooms, more kids will get sick with an illness that can have devastating longterm effects. Isn't it time to better weigh the costs and benefits to realize the benefits of clean air for the health of students is worth the electrical costs. People are volunteering to supply them!! In all the classrooms using them in the hyper-litigious United State, none have seen lawsuits from parents!! Since their introduction in 2020, there has been zero harm caused by CR boxes. We can't say the same for Covid. So what on earth are they afraid of?? 

Is the cost of the electricity used (which is much less from CR boxes than HEPAs, by the way) really the stopper keeping us from protecting children?? 

Remember Ben Franklin's advice: an ounce of prevention is worth a pound of cure.

So bloody crazy-making!