Al Haddrell

Bruh

You do important work! I want to make sure you’re able to make more of it!

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Phenomenal new Morawska paper!

@ukhadds.bsky.social @brownecfm.bsky.social
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Where did you read that? The New York Times? Cause it seems like it's happening right now....

Field test of a novel detection device for Mycobacterium tuberculosis antigen in cough - BMC Infectious Diseases Background Tuberculosis is a highly infectious disease that is spread from person to person by infected aerosols emitted by patients with respiratory forms of the disease. We describe a novel device t...

Interesting technique, thanks for flagging it up. Here's the paper they published on it.

link.springer.com/article/10.1...

Well done! And good job by your workplace to take your criticism on board. Amazing what a single person/vent fan and fresh air duct can accomplish.

Absolute nightmare.

That would be one way to do it. The collection +PCR takes hours so it'll be a while before it's anything approaching real-time. But as you say, it's a novel way to detect exhaled aerosol specifically, so we can use it to benchmark against more rapid techniques.

True. But it's a step in a novel direction, and thinking about this in a different way. Being able to identify just respiratory aerosol will be key

As for absorption, WIBS have been around for a while and I haven't seen studies showing them able to identify respiratory aerosol. It's challenging.

I posted it from my phone and messed it up. It's here:

bsky.app/profile/crai...

Thanks!

Thanks! Thats the one.

I posted it from my phone, so I may have done it wrong.

The risk of the airborne transmission of disease correlates with the amount of infectious exhaled aerosol. Since people exhale CO2 with aerosol, its conc has been used as proxy for exhaled aerosol

In this article, researchers propose a new way to estimate risk of transmission

PCR takes a while to report a signal, so these measurements aren’t in real-time. That said, it’s an interesting approach and step in a new and exciting direction.

Anyway, those are my thoughts on this cool new study. A good proof of concept.

Check it out.

They also looked for SARS-CoV-2 in their air samples and found them as well. They were then able to normalize the viral load to the amount of exhaled aerosol. This tells you where there are more infectious exhaled aerosol in given space.

They tested their technique in a hospital and found that it worked in a complex environment. Shown here the relative amount of respiratory aerosol detected in different places in a hospital.

They use PCR to identify the DNA of the various microbes in exhaled aerosol. To do this, they had volunteers sing “Happy Birthday” and collected the exhaled aerosol with a bioaerosol sampler. They then tested for the specific microbes DNA and found many copies.

Bodily fluids will contain many microbes that are nonharmful or even beneficial. In this study, they collected exhaled aerosol and measured something they call the airborne respiratory microflora (ARM). This is essentially the mixture of non-pathogenic microbes in exhaled aerosol.

Flora - Wikipedia

Infectious microbes are transmitted on exhaled aerosol. The initial composition of exhaled aerosol is essentially saliva or lung fluid. Meaning it’s a complex mixture of salts, sugars, surfactants, mucins and proteins….

And microbes (the flora).

en.wikipedia.org/wiki/Flora?w...

So, rather than using CO2 to estimate risk, the authors propose developing a technique to measure the amount of just the exhaled aerosol in a room.

The challenge then becomes, how do you determine an aerosol is an exhaled aerosol?

YouTube video by Al Haddrell How Does CO2 Concentration Correlate with Exhaled Aerosol?

For a variety of reasons, CO2 may not be a good proxy for exhaled aerosol. eg, it will underestimate the risk when people are talking, or overestimate when filtration is used.

I walked through some of this in my explainer video (excerpt shown below):

youtu.be/mRPh06y6hIU

Here’s a link to the article (the first author is Henry Oswin, a former PhD student from our group who is currently working with Lidia Morawska):

sciencedirect.com/science/articl…

The risk of the airborne transmission of disease correlates with the amount of infectious exhaled aerosol. Since people exhale CO2 with aerosol, its conc has been used as proxy for exhaled aerosol

In this article, researchers propose a new way to estimate risk of transmission

I’ve built a CELEBS for some collaborators in the USA. They’ve been looking at measles with it. Hopefully they’ll be publishing the results soon.

YouTube video by Al Haddrell Are Microbes on the Surface of Aerosol? aka: How instant coffee informs disease transmission

How long a microbe remains viable in the air will depend on where it resides in/on an aerosol. So then, how do scientists figure out where?

Answer: they use their understanding of the processes involved in industrial food production. Namely, coffee.

youtu.be/HHwp4tLPK9M

Yeah, that's one of the useful AI tools out there....

If you have any questions, please let me know.

YouTube video by Al Haddrell Designing the Air: Maximizing Viral Decay to Limit Disease Transmission (WIAC2025)

This is an excert from a lecture I gave (and re-recorded) last summer. In this lecture, I discussed the approach
we use in the University of Bristol to study airborne pathogens. You can find the whole lecture here:

youtu.be/iZxnbxgG5zI

YouTube video by Al Haddrell Are Microbes on the Surface of Aerosol? aka: How instant coffee informs disease transmission

How long a microbe remains viable in the air will depend on where it resides in/on an aerosol. So then, how do scientists figure out where?

Answer: they use their understanding of the processes involved in industrial food production. Namely, coffee.

youtu.be/HHwp4tLPK9M