The fundamental difference between cigarette smoke and heated tobacco aerosol

      For our second ever Open Science event, we decided to focus on one of the biggest problems with cigarettes: burning. It's the burning, or combustion, of tobacco that creates cigarette smoke and generates high levels of harmful chemicals. By heating instead of burning tobacco, we can avoid creating smoke and thus many of those harmful chemicals, and the levels of those chemicals that are present may be significantly reduced. This Open Science webinar will walk you through some of our most fundamental research on the aerosol of our leading heated tobacco product (HTP).

      Open Science

      Cigarette smoke vs HTP aerosol

      Many people believe that cigarette smoke and heated tobacco aerosol are the same, but they are not. In fact they are very different. Both fall under the category of aerosols, but how they are formed and what they're made of set them far apart from each other. Reducing and controlling the temperature is the key to avoid burning the tobacco, and thus to avoid creating smoke. Check out the information on this page and watch the webinar to learn more about the differences between cigarette smoke and heated tobacco aerosol.

      Webinar and presentations

      We hosted a webinar on September 15, 2020, where our scientists walked the audience through our research on this topic in detail. Dr. Gizelle Baker, Director Global Scientific Engagement, hosted three sessions, each with a live Q&A. Here are our five presenters and their topics:

      Reports: our research on HTP aerosol

      Our scientists have studied the aerosol of our leading heated tobacco product in depth, comparing it against cigarette smoke at each step along the way. Those findings have been published in two reports already available on PMI Science.

      Q&A from Open Science, September 2020

      Here are a few of the most asked questions from our September Open Science event, along with our answers to those questions from the sessions.

      We look at the different studies being published, and assess the study design, the methods, the test products, and the scientific approach. Because it's all important to understanding the results.

      The easiest way to look at this question about the toxicity of the Tobacco Heating System (THS) aerosol is to look at the FDA conclusions based on our scientific dossier. The FDA received all of our toxicological studies. These studies looked at the complete aerosol that is generated by THS. This aerosol includes the propylene glycol and the glycerin. In the end, the FDA concluded that overall, there was a lower toxic potential for THS despite the fact that there may be increases in some of the chemicals.

      These two specific compounds, which are used to form the aerosol in e-cigarettes and THS, have been very well studied. It is important that these are of the appropriate chemical grade, and that any heating that takes place of these compounds is controlled. So, an e-cigarettes using a high-power setting, could heat the e-liquid at quite high temperatures, which could generate compounds like glycidol, which is a known toxin. But the levels of these compounds are extremely low in devices that are operating properly. So, it's unlikely that this is a major issue for THS and we would direct people to have a look at the recent review by UK Committee on Toxicity, where they reviewed e-cigarettes.

      The fact is that both THS and e-cigarettes emit aerosols that are both generated in the absence of combustion. These aerosols are not smoke, as there is no combustion. Aerosol droplets are instead formed from the vapors of the aerosol former, which is glycerol, that is evaporated from the tobacco during the heating. When the vapor of this aerosol former later cools down, it condenses to form liquid droplets.

      The very same process of vaporization and condensation happens in e-vapor products. There are aerosol formers in the e-liquid: propylene glycol and glycerol. Both are vaporized when the liquid is heated by the heating element. In the same way as for heated tobacco products, these vapors form an aerosol when they cool down and condense into liquid droplets. Both of the aerosols are liquid-based aerosol, containing fewer and lower levels of harmful and potentially harmful constituents compared to the smoke from combusted products, which contain thousands of chemicals and solid particles because it is the combustion that generates these solid particles.

      I would like to emphasize the similarities between those two products. As there is no combustion in either product, they do not generate sidestream smoke. When these products are being used there are only a few components that are present in air above the levels of background, and it can be attributed to the exhaled aerosol of these products.

      More importantly, because there is no combustion, those products will not generate smoke, and therefore do not produce second-hand smoke. In the air, we can measure a small level of glycerin and/or propylene glycol and nicotine, and for THS, we also saw a small level of acetaldehyde.

      Although e-cigarettes are a category of products, we have conducted studies with different types of e-cigarettes, rechargeable, tank-refillable products, etc., so we have a broad view of how they affect indoor air quality.