If you ever had anything to do with Fire Safety Engineering, you have most likely touched the visibility in smoke. What's an easier way to explain how bad the conditions are inside of a building than saying how much smoke was there? And what's a better way to define smoke than saying how far can you see? It's brilliant. We have agreed (unwillingly, somewhere in the '60s) that if visibility is kept at a good'ish level of 10 m or more, conditions inside are fine.  And we know how to calculate it, so it seems we're in a great place.

Well. Not really. Our models for this are quite bad. And there is no one reason for that - from physics, through the assumptions, commonly used constants (magical numbers if you prefer that name) to implementation of this approach into CFD, which was never foreseen by its creators. Together with prof Lukas Arnold we have figured out that this requires not only an improvement but preferably - a complete revamp. After that, we have written a grant application, and guess what - WE GOT IT!!!

In this episode, you will learn everything about the faults of the visibility in the smoke model and how we intend to change it. Please join us in this discussion, and if you have some great ideas on how to make our work better, please be sure to tell us! We are listening and looking forward to changing the FSE together, forever.

As we are just starting, please feel welcome to check existing resources by our teams on the visibility in smoke:

• Fire Science Show Episode 3 with Gabriele Vigne - there is this crazy fire podcast that covers so much!
•  My presentation at UK Fire and Smoke Modelling Forum on YouTube with a lot of background on how the model works (or rather, why it does not work)
• Robust value of Soot Yield for complex materials found at 0.1 with Gabriele Vigne
• Multi-wavelength sensitivity of the smoke obscuration models by W. Wegrzynski et al.
• How to measure visibility in a small scale? by W. Wegrzynski et al.
• A map representation of ASET-RSET by B. Schroeder et al.
• Spatiotemporal measurement of light extinction coefficients in compartment fires by L. Arnold et. al

This research was funded in part by National Science Centre, Poland in the grant OPUS 2020/39/I/ST8/03159.

Thank you to the SFPE for recognizing me with the 2025 SFPE Fire Safety Engineering Award! Huge thanks to YOU for being a part of this, and big thanks to the OFR for supporting me over the years.

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