HEPA FILTER MYTH vs. FACT

When the novel coronavirus burst onto the scene, it quickly realized that the mighty HEPA filter was one of its greatest foes.
It began an aggressive anti-HEPA filter lobbying campaign with politicians, public health officials and school boards.

1/9
The goal was to spread lies about HEPA filters to ensure it could infect as many kids as possible. These gullible individuals have been doing PR for the virus and the lies need to be put to rest.

2/9
Myth: HEPA filters blow the virus around
Fact: They remove the virus from the air

3/9
Myth: HEPA filters interfere with ventilation
Fact: No they don't

4/9
Myth: HEPA filters aren't needed if minimum ventilation standards are met
Fact: HEPA filters reduce risk for airborne pathogens, even if there is already ventilation.


5/9
Myth: HEPA filters can only filter down to 0.3 microns
Fact: Not true


6/9
Myth: The virus is too small for a HEPA filter
Fact: The virus is inside aerosols that can get filtered out


7/9
Myth: Electrical safety issues
Fact: >100000 classrooms. No issues

Myth: Child safety issues
Fact: >100000 classrooms. No issues

Myth: They are inequitable
Fact: So put one everywhere

8/9
CONCLUSION

Using HEPA filters is a simple way to clean the virus out of the air. It can be deployed everywhere really quickly. Air filtration is one of the main tools we have against this virus and we need to start using it. Making up lies puts everyone at risk.

9/9

• • •

Missing some Tweet in this thread? You can try to force a refresh
 

Keep Current with Joey Fox, P. Eng, M.A.Sc

Joey Fox, P. Eng, M.A.Sc Profile picture

Stay in touch and get notified when new unrolls are available from this author!

Read all threads

This Thread may be Removed Anytime!

PDF

Twitter may remove this content at anytime! Save it as PDF for later use!

Try unrolling a thread yourself!

how to unroll video
  1. Follow @ThreadReaderApp to mention us!

  2. From a Twitter thread mention us with a keyword "unroll"
@threadreaderapp unroll

Practice here first or read more on our help page!

More from @joeyfox85

Jan 19
THEY BLOW THE VIRUS AROUND

This is one of the most prevalent lies against HEPA filters. It’s been used by school boards and politicians as an excuse to not put HEPA filters into schools. This myth needs a thorough debunking.

1/9
AEROSOL SPREAD IN A CLASSROOM

The air in a classroom is well mixed. Anyone who is concerned about blowing the virus around needs to know that it's already been blown around. Here's a diagram of what classroom airflow looks like:



2/9
Here's a document from ASHRAE discussing the well-mixed assumption for classrooms.

"...the well mixed assumption in the Wells-Riley model may hold better for these [smaller] particle sizes."

ashrae.org/file%20library…

3/9
Read 9 tweets
Jan 17
THE MINI #corsirosenthalbox

Here it is:

1/6
Fan from here:
(the one displayed on the wayfair website was not the one shipped. It's seen on the amazon website.)

2/6

wayfair.ca/home-improveme…

amazon.com/Comfort-Zone-P…

H/T @Flying_Donny
Filters from here:

3/6

amazon.ca/FilterBuy-10x1…
Read 6 tweets
Jan 16
BUYING A HEPA FILTER FOR YOUR HOME 🧵

I've been asked about sizing a HEPA filter for your home. This is different than sizing one for public spaces with other people.

This does not provide fresh air. Ventilation is required for that. Here are some things to consider:

1/10
WHAT IS YOUR GOAL?

Do you just want to improve the air quality in your house in general or do you want to have a gathering and use the HEPA filter to mitigate risk of COVID transmission? The clean air delivery rate (CADR) for these two goals is very different.

2/10
For basic air quality improvement, go here: ashrae.org/technical-reso…

Click on standard 62.2-2019. Top of page 8 has a table based on house size.

Consider poor air mixing between rooms. Ex - your bedroom door is closed. HEPA filter outside won't help.

3/10
Read 10 tweets
Jan 13
MISUSING THE HIERARCHY OF CONTROLS

The hierarchy of controls is a system to reduce or eliminate exposure to hazards. It has been misused by people pushing an anti-mask agenda. They misunderstand how this works.

1/6 Image
Here's Martha Fulford misunderstanding it to push an anti-mask agenda.

2/6

Respirators (N95, KN95...) right now are the most effective tools to prevent infection. It's preferable to use the other methods, but the other methods don't work as well.

Here's how the different controls can be used to combat COVID (some is up for debate):

3/6
Read 6 tweets
Jan 10
SCHOOL VENTILATION MYTHBUSTERS

MYTH: Mechanical Ventilation + MERV-13 renders other measures ineffective.

FACT: Various measures are cumulative (they add together).

This misinformation has been pushed by public health and school boards and it needs to be stopped.

1/7
If you have 3 ACH (air changes/hour) from air being supplied through mechanical ventilation/filtration and 2 ACH being supplied by stand-alone HEPA filters, you have a total of 5 ACH. (3+2=5)

5 ACH > 3 ACH

It's pretty easy to understand.

2/7
Those who have been pushing this misinformation didn't bother checking with engineers. They are stating blatantly incorrect facts about ventilation/filtration when they do not know what they are talking about.

3/7
Read 7 tweets
Jan 6
CONVINCING SCHOOLS TO PUT IN A #corsirosenthalbox

CR Boxes are a cheap, quick and effective way to increase filtration. They are one of the best tools we have right now to protect kids from COVID. How to get them into classrooms?

1/13
First, call up the teacher, principal, superintendent, trustee and tell them about these. Recommending that the kids build them themselves in science class might help. You'll definitely get resistance though, here are some counter arguments:

2/13
ALREADY HAVE A HEPA FILTER

What HEPA filters they are using? Are they run on high (probably not)? What's the CADR? They aren't going to do anything meaningful. At least ask that they be run on high speed and if not, they need more filtration.



3/13
Read 13 tweets

Did Thread Reader help you today?

Support us! We are indie developers!


This site is made by just two indie developers on a laptop doing marketing, support and development! Read more about the story.

Become a Premium Member ($3/month or $30/year) and get exclusive features!

Become Premium

Too expensive? Make a small donation by buying us coffee ($5) or help with server cost ($10)

Donate via Paypal

Or Donate anonymously using crypto!

Ethereum

0xfe58350B80634f60Fa6Dc149a72b4DFbc17D341E copy

Bitcoin

3ATGMxNzCUFzxpMCHL5sWSt4DVtS8UqXpi copy

Thank you for your support!

Follow Us on Twitter!

:(