In this episode of Science Series with Roberto Sussman, we tackle a deceptively simple question: how do you determine optimal vaping settings in a laboratory? Roberto explains why machine “puffing” can produce unrealistic overheating conditions that real users would immediately avoid (too hot, bad taste), and how that can distort measurements and conclusions in some studies. We also cover the “dry puff”/dry heat phenomenon, why airflow and power settings matter, and how modern devices differ from early closed “cigalike” systems.
Transcription:
00:04 - 00:19
[Host]
Welcome to another episode of Science Series with Roberto Sussman. In today's program, we're going to examine a deceptively simple question that sits at the intersection of physics, chemistry, and public health research. How can we determine the optimal vaping settings in a laboratory?
00:21 - 12:21
[Roberto Sussman]
First, we have to distinguish between a human using the device and a machine. In the case of inhaled aerosol, you have to use a machine to simulate the inhalation because when you inhale, the aerosol goes into your respiratory system and you cannot put instruments there to capture, to collect the aerosol or to measure it. You cannot put instruments inside of the body. So it has to be a machine that will pull out the aerosol with a pump, typically this is done with a pump, and the aerosol is going to be pulled out and it will be analyzed by different methods. Depending on what type of compound you want to focus, you use different methods of collection, extraction, and analysis, right? So a human will feel, will taste. If it is too hot, if the mouthpiece is very hot, the human will feel it. If the aerosol is tasting badly, well, the human user will discontinue using, right? Because nobody wants to inhale an aerosol that tastes very bad or that is too hot, that is too annoying, unless you are a suicidal person, you stop using it. But the machine doesn't. The machine might be extracting an aerosol that for a human would be terrible. But the machine is operating, right? People believe that overheating conditions would burn the machine. No. That's only in the extreme case where you have a dry heat and the liquid is completely depleted. And then the temperatures in the coil can reach combustion temperatures, like 900 degrees. And in that case, then you still have a burning situation. The point is that human users already feel the onset of overheating well before the dry heat, right? Well before. And that's why sometimes the experiments that are carried in the laboratory, they think that everything is normal because they see that the liquid is not depleted. In fact, they can replenish the liquid, right? And then they believe that everything is normal. But a user that would be a human vapor that would be inhaling this aerosol would find it terrible. But it is a machine, those operating the machine who are not... not aware of the type of settings that vapers use, it is very easy that they will be testing the devices in conditions that humans would never use them, right? It's important to see that. Let me just clarify one point. You have to distinguish between the very early vaping devices, the cigar lights. They were released around 2009, 2010. They looked like metallic cigarettes. And the technology was very poor because the liquid was in contact with the solders and the coil and plastics and so on. And they were closed. You couldn't open them or correct anything. They were closed systems with a poor technology, and they had no control. You could not control power, voltage, nothing. They were just cylinders that you pop them, right? And they operated at very low power. So for this type of devices, the overheating process can be very fast and can be very sudden. So what happened, you were using these SIGA lights, and since they were completely closed, you were not aware that the liquid was depleting. And it was very easy to get a dry heat. That is, that the device was operating under overheating conditions, where I think I have described them, right? The overheating conditions. These are conditions where the cycle of energy, energy supply and energy absorption is broken and a lot of residual heat accumulates inside of the devices and it changes the chemistry completely of the aerosol. This could happen in a very sudden way in all devices. Some people assumed that it was one single event, everything normal. Suddenly, the liquid depleted and bang, dry heat. But once the devices became more sophisticated, that they allow you to control power, and they also, you were able to refuel them, and you could see the liquid inside of the tank. This situation changed completely and improved a lot. It was much easier to monitor that the levels of liquid were okay, and also you were instructed to change the coil, because if you never change the coil, then you have all sorts of physical problems, corrosion, leaking, and this process influenced the chemistry, right? You know, this is the same with any consumer product. If you have a car, you never check the brakes. You never tune it up. You never give any maintenance to this car. Well, that car is a disaster and can be dangerous. It can crash, right? So the same thing with electronic cigarettes. If you do not give them maintenance and attention, minimal, you don't have to be obsessed with that. But you have to change the liquid, to change the coils periodically, and then it will work well. Now, more modern devices, it was much easier to prevent this sudden dry puff. You could monitor the liquid, et cetera. But still, sometimes, here with more sophisticated devices, starting from generation 2 onwards, that you have more control over the devices, then you can say that overheating happened when the users were not using it properly. But again, there is a safety valve, because if I'm using this device and I don't use it properly, what can it mean? I don't with the right airflow, I do not give maintenance. Then overheating might happen because of deviation from the recommended usage. But this is for humans, right? If I test this device with a machine that is a very typical case, And here I let you go to the next question. A very typical case, not the only one, but very typical, it is when you are machine puffing a very high-powered device. Very high-powered device generates a lot of aerosol, right? So you need a lot of airflow. to evacuate and cool this aerosol, right? So a human user has a very powerful device and it inhales very weakly. So after, the user will feel a very hot aerosol. Why? Because this amount of aerosol requires a lot of airflow, right? And if you puff it, like if you are puffing a small device and it's a big device, you will get a very hot aerosol. So what will the user do? The user will discontinue or will try to inhale with a much stronger airflow. But tell this to a machine. Not talking to a machine. Those conducting the experiment, they set up the machine. You can set up the airflow of the machine. This is part of, you can set it up. So they set it up with air flows that would be equivalent, that we appropriate, would be appropriate, for a low power device. But they're testing a monster, right? But the machine is not going to complain. The machine is not going to say, ah, I'm burning my mouth, oh. The aerosol is awful, but the machine will work. And the authors of this, some of the researchers in these experiments, are people who are not aware of the consumer patterns, and they think that They are ignorant in the sense that they believe that as long as there is liquid, there is no dry puff, and everything is fine. But it's not fine. So we have seen studies that are testing a device at 200 watts, puffing it with the airflow that would be appropriate for a device running at 5 watts. You see, 200 watts? generates an enormous amount of vapor and you are evacuating this vapor with a tiny air flow. So of course they detect metals, they detect formaldehyde, they detect carbon monoxide, they detect all sorts of things in a very artificial way, right? And this happens all the time. Sometimes they use this aerosol, this poisonous aerosol, to expose mice and cells. And then they say that, wait, this is very dangerous. But it is not true. They are really doing very bad experiments.