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Article | Aerosol Chemistry | Apr 4, 2023

Methods for generating and testing aerosol from THS

Cigarette smoke is produced when the tobacco in a cigarette burns at temperatures in excess of 600 °C. At such high temperatures, the tobacco is burned to ash and generates smoke that contains thousands of chemicals, including high levels of harmful and potentially harmful constituents (HPHCs) many of which have been recognized by public health authorities to be the most likely causes of smoking-related diseases.

The Tobacco Heating System (THS, commercialized as IQOS), on the other hand, heats tobacco without burning it to generate a nicotine-containing aerosol with significantly lower levels of HPHCs. It is an electronic device, and it generates an aerosol that is fundamentally different from cigarette smoke. For example, the aerosol of the THS contains about 80% water, whereas cigarette smoke contains only about 10% water. Because of these facts, some of the standard methods used to assess cigarettes cannot be applied and do not produce accurate measurements of certain aerosol constituents without modification. We provide the full methodology, including a detailed description of these modifications and step-by-step instructions for collecting the aerosol of THS using a commercial linear smoking machine.

You can find methods and protocols related to our assessment of THS aerosol in our publications library by filtering for "methods and protocols." A summary of the technologies that we use to analyze THS aerosol is shown below:

Aerosol Studies

Find out how we concluded our Tobacco Heating System does not burn tobacco nor create smoke.

The PMI-58 list of Harmful and Potentially Harmful Constituents

See the levels of toxicants in THS aerosol compared with cigarette smoke according to the FDA-93 list

Tobacco heating system's mainstream aerosol compared to reference cigarette smoke

We observed an average of 90-95% reduction of the levels of HPHCs in the THS aerosol.

FDA's list of HPHCs

See the levels of toxicants in THS aerosol compared to cigarette smoke according to the FDA-93 list.

Close-up shot of microscope with metal lens at microbiological laboratory

Untargeted Assessment Strategy

See the methods and results behind our comprehensive, untargeted screening of smoke-free product aerosols.

Comprehensive chemical characterization of the aerosol generated by the Tobacco Heating System

Untargeted screening further confirms reduced average levels of harmful chemicals in THS aerosol compared to cigarette smoke.

Transparency in science to promote best practices

PMI shares state-of-the-art methods for smoke-free products assessment.

How does PMI conduct its scientific assessments?

We developed a risk-based Quality Management System for our smoke-free products covering its complete lifecycle, from the conception through to commercialization. 

PMIScience.com is operated by Philip Morris International for the purpose of publishing and disseminating scientific information about Philip Morris International’s efforts to develop and assess products that have the potential to reduce individual risk and population harm associated with tobacco use. This site is for use by scientists, the public health and regulatory communities, and other stakeholders with an interest in tobacco policy. The purpose of this site is not for advertising or marketing. It is not intended for use by consumers.

Reduced Risk Products ("RRPs”) is the term we use to refer to products that present, are likely to present, or have the potential to present less risk of harm to smokers who switch to these products versus continuing smoking. PMI has a range of RRPs in various stages of development, scientific assessment and commercialization. Our RRPs are smoke-free products that produce an aerosol that contains far lower quantities of harmful and potentially harmful constituents than found in cigarette smoke.