Thread by @BarryHunt008

Another junk RCT came out

This time claiming "air purifiers don't reduce exposure to viruses in classrooms"

BOLLOCKS

1st clue this was going to be a junk study: they did an RCT

Wrong tool

There is no equipoise, no unknown or barely discernible benefit to weigh against likely harm

2nd - Many studies already show cause & effect & mathematically quantify the relationship between exposure levels / reduction levels of pathogens in air and infections

An RCT is two steps backwards at this point

And could be considered unethical

3rd - the conclusion is not supported by the data

Not even close

"The HEPA purifier intervention was not associated with lower odds of high viral exposure (odds ratio [OR], 0.50; 95% CI, 0.08-3.25; P = .46)"

What's wrong with this statement?

Let me tell you

An odds ratio of 0.50 means the intervention WAS ASSOCIATED with a 50% reduction

Pretty good, eh?

Except the range of 0.08 to 3.25 is bonkers

And a p value of .46 is garbage

It means the experiment was junk

The conclusion should have been, "we did something wrong"

4th - There were many things they did wrong, starting with no scale or context or apples-to-apples standardization

Where is the detail showing base ACH and additional eACH provided by air purifiers?

🤷‍♂️

Without that basic information, how do you know your intervention has the effect size it needs?

In this case, how do you know if the air purifiers have the CADR needed to see an effect?

🤷‍♂️

How do you know if you're meeting basic Standards guiding ventilation for infection prevention?

🤷‍♂️

Answer is, you don't. And in this case, the air purifiers were clearly undersized

I don't mean physically, I mean CADR

So much so they put 4 of them into each classroom

They would have needed 12

5th - kids are in classroom 5 days / week x 6h / day = 30 hours but the measurements were taken after one week of sampling = 24h / day x 7 days / week = 168 hours

30h / 168h = 18% of the time viruses are shed into the air

So you're looking for a result while ignoring the fact that 82% of the time the air purifiers are just cleaning clean air

Ignoring the fact that there is a mismatch between shedding & sampling

Ignoring that whatever the result is, it's diluted 5-fold

The units chosen were expensive, undersized, the application was impractical & not scalable, there was no reference to existing Standards, they used the wrong experimental tool, ignored fallow time, came to the wrong conclusion, & published inflammatory disinformation in a prestigious journal

I give it an F

We have to stop funding junk science with taxpayer dollars

We have to stop publishing junk science in prestigious journals

Or stop calling them prestigious journals

We have to stop junk science being weaponized to block real-world interventions that work to protect the public

Al Haddrell .@ukhadds has more to say on the matter

https://twitter.com/ukhadds/status/1977990481591078984