22 January 2019 | Philip Morris International R&D
A PDF VERSION OF THE EXECUTIVE SUMMARY IS AVAILABLE HERE.
Philip Morris International’s (PMI) Electrically Heated Tobacco Product (EHTP) is designed as a
novel tobacco product that generates a nicotine-containing aerosol without involving a
combustion process and formation of smoke when used in the Electrically Heated Tobacco System
(EHTS) Holder. Thus, the absence of combustion and smoke during EHTS use is by design. The
scientific evidence available on EHTS use comprehensively demonstrates that no combustion
process occurs when the EHTP is used in the EHTS Holder and that the aerosol generated is not
Furthermore, there is no Environmental Tobacco Smoke (ETS) emitted during use of the EHTS. In
addition, EHTS use has no adverse effect on air quality according to threshold limits established by
existing air quality guidelines and when used in a setting where regulatory norms of adequate
ventilation are respected.
The EHTS is also known as the Tobacco Heating System (THS) 2.2 and marketed in various countries
under the brand name IQOS
Key takeaways of the scientific reports presented here include:
Absence of combustion
- o Combustion (burning) is defined as a chemical process of oxidation that occurs at a rate
fast enough to produce heat and usually light in the form of either a glow or flame.
- o For the tobacco in the EHTP to combust, its temperature would need to exceed about
- o The maximum temperature measured in the EHTP during use of the EHTS is 320°C and
therefore is well below the temperature required for combustion. The majority of the
tobacco in the EHTP remains at much lower temperatures.
- o The EHTP tobacco undergoes drying and evaporation during EHTS use, and only a small
portion of the tobacco close to the Heater undergoes thermochemical decomposition
(torrefaction/low-temperature pyrolysis), but no combustion (neither incomplete nor
- o Furthermore, there are no signs of net exothermic (heat-generating) processes in the EHTP
during use of the EHTS. In fact, when the power to the Heater is switched off, there is an
immediate decrease in the temperature of the tobacco.
- o Oxygen is necessary for combustion. The comparison of the EHTS aerosol generated in
oxidative (air) and non-oxidative (nitrogen) environments indicated that oxygen does not
play a major role in the thermochemical degradation of the EHTP tobacco and further
demonstrated the absence of combustion.
- o Although gaseous compounds, such as carbon monoxide, carbon dioxide, and nitrogen
oxides, are usually associated with combustion, low levels of these compounds in the EHTS
aerosol are not evidence that combustion has occurred. These compounds are also
generated at low levels during thermochemical degradation (torrefaction or mild pyrolysis)
of the tobacco material, independent of the oxygen availability
No smoke formation
- o While smoke is an aerosol, not all aerosols are smoke.
- o Smoke is an aerosol containing liquid and solid particles (particulate matter).
- o Smoke particulate matter is formed when products of combustion and high-temperature
pyrolysis (e.g., hydrocarbons) reach supersaturation and either condense to form droplets
or react together to form particles, or by the nucleation and growth of positively charged
hydrocarbon ions to form soot particles.
- o The EHTS aerosol is not smoke, as there is no combustion or high temperature pyrolysis
occurring in the EHTP during EHTS use, no solid particles are generated, and the liquid
particulate matter (droplets) are not formed from condensation of byproducts of
combustion or pyrolysis.
- o The liquid particulate matter in the EHTS aerosol is instead generated when glycerol (added
to the tobacco during processing as an aerosol former) is vaporized and reaches
supersaturation and condenses on cooling, forming nuclei, onto which other constituents
can condense to form droplets.
- o Aerosols formed from the condensation of water vapor or vaporized aerosol formers from
e-liquids or tobacco materials, such as the EHTS aerosol, are very different in terms of origin
as well as chemical and physical composition compared with cigarette smoke, which is
formed from the combustion and associated high-temperature pyrolysis products
generated from the burning of tobacco.
- o The processes that generate the aerosol during the use of EHTS and for most e-vapor
products (EVP) are the same. Such products involve heating to vaporize aerosol former(s),
and inhalable liquid aerosol droplets are formed as the vapor cools down.
- o The absence of combustion in the EHTP and that the aerosol generated is not smoke have
been substantiated by scientific evidence and verified by third-party scientific experts in
numerous countries as well as by independent research organizations.
No emitted Environmental Tobacco Smoke (ETS)
- o It is important to note that the purpose of PMI studies on the impact of EHTS use on air
quality is to fully characterize the impact of EHTS use on the environment and on
bystanders as well as to provide scientific evidence to support the creation and
implementation of science-based policies for new emerging, less-harmful products, such
as the EHTS. The intention is not to establish evidence in support of overcoming existing,
already implemented smoking bans in any country.
- o ETS is generated by the combustion of tobacco products and is composed of sidestream
smoke, emitted from the smoldering tobacco, as well as exhaled mainstream smoke from
- o As there is neither sidestream nor mainstream smoke generated by the EHTP during EHTS
use, there is no ETS emitted.
- o The EHTS aerosol generated during use of the EHTS contains >90% lower levels of harmful
and potentially harmful constituents, on average, compared with mainstream cigarette
- o The environmental EHTS aerosol emitted during EHTS use (predominantly emitted from
exhalation of EHTS mainstream aerosol constituents during EHTS use) is, by nature,
different from the ETS emissions from cigarette smoking.
- o In addition to demonstrating that the EHTS aerosol is not smoke and that no ETS is emitted
during EHTS use, it is important to assess the impact of the environmental EHTS aerosol on
air quality. PMI conducted scientific studies in a dedicated air quality assessment room
under simulated environmental conditions.
- o These studies demonstrated that only three compounds (nicotine, acetaldehyde, and
glycerol) were above the background levels in air and could be attributed to EHTS use.
However, glycerol is not an air pollutant and the concentrations of nicotine and
acetaldehyde were much lower than the levels measured after cigarette smoking and far
below the limits established by existing air quality guidelines.
- o Independent studies on EHTS (as
well as certain EVPs) use in indoor environments, in general, corroborated these results.
- o To better understand the impact of day-to-day activities on air quality and to prepare the
assessment of the impact of EHTS use in real-life settings, PMI conducted studies on the
impact of activities of daily living, such as using perfume and cooking, on air quality
- The results of these studies showed that day-to-day activities lead to significant
emissions of volatile organic compounds and particulate matter, which would need
to be considered when assessing the impact of EHTS use on bystanders in real-life
- o In a study conducted in Japan, in a restaurant where EHTS use was allowed but cigarette
smoking was not, the results indicated that:
- EHTS use did not negatively affect bystanders’ exposure in a real-life setting when
passively exposed to the environmental EHTS aerosol.
- EHTS use had no adverse effect on air quality, considering threshold limits
established by existing air quality guidelines and when used in settings where
regulatory norms of adequate ventilation are respected.
- o Independent scientific studies on air quality conducted in real-life settings in a nightclub
and in a catering and entertainment establishment showed that:
- The particle number concentration was found to be higher when the nightclub was
in full operation with no humans present and no use of EHTS compared with what
could be measured when EHTS was used and the nightclub was not in operation.
- The levels of all compounds measured in the catering and entertainment
establishment during EHTS use were far below threshold limits established by
existing air quality guidelines.
- o Moreover, the results from an independent study performed in Germany were in line with
the results of PMI studies on air quality, with cigarette smoking leading to the greatest
impact on air quality. EHTS use resulted in detectable levels of nicotine, but no other
chemical markers of contamination were detected, including the absence of markers for
In summary, the scientific evidence demonstrates that there is no combustion in the EHTS, the
aerosol generated is not smoke, and there is no ETS emitted during use of the EHTS. In addition,
EHTS use has no adverse effect on air quality, considering threshold limits established by existing
air quality guidelines and when used in a setting where regulatory norms of adequate ventilation