Independent research on heated tobacco products

We at Philip Morris International (PMI) are committed to transparency in science. We share our research through peer-reviewed articles and open access publications, and at the same time we welcome and encourage independent research on our smoke-free products and our methods and results. Over the past few years, a rapidly growing number of organizations and institutions have conducted and published studies on smoke-free products. This page outlines our approach to tracking independent publications on heated tobacco products (HTPs) and illustrates the evolution of the independent publication landscape.

Updated: 26 November 2025

Heated tobacco products research landscape

In recent years, the independent research landscape has evolved significantly, with a growing number of organizations and institutions conducting studies on smoke-free products.

The number of independent studies focusing on HTPs, particularly PMI's heat-not-burn products, has shown a significant upward trend over time. By the end of 2017, there were less than 20 independent papers published annually. Now, we see over 200 research papers published per year, covering original data, analysis, methodology, case reports, and reviews on HTPs. And that does not include many commentaries and opinion pieces that are also published.

To date, we have counted more than 1,000 independent publications on the HTP category meeting these criteria. Many of these are focused on the Tobacco Heating System (THS).

These studies often reinforce key findings from our own research efforts. However, it is important to acknowledge that variations may exist between studies, including differing results, data interpretations, methodological approaches, and conclusions drawn.

It is essential to recognize that individual studies, regardless of their quality, only provide a fragment of the overall picture. A comprehensive understanding of the harm reduction potential of our smoke-free products emerges from the accumulation of evidence over time.

How do we keep track of independent studies on heated tobacco products?

We have developed a database of scientific literature on smoke-free products, which includes a thorough coverage of HTPs. This library is designed to include articles published in peer-reviewed journals, regardless of whether they are authored by PMI or independent third parties.

Our data collection and analysis approach leverages leading scientific publication databases, including RightFind, PubMed^®, Scopus, Embase, SciFinder^®, and Google Scholar. This approach helps ensure that our analysis is based on a wide range of sources and provides a robust understanding of the research landscape on HTPs. The collected literature covers a wide range of scientific disciplines (i.e., product design, aerosol science, indoor air quality, preclinical toxicology, clinical and health outcomes research, awareness and perception, prevalence and use patterns, and population modeling) as well as broader areas (i.e., policy and marketing).

The resulting library is maintained and updated regularly. Specific search strings are optimized for HTPs. Since some publication databases are not open access, we provide the search strings for those who can access them through subscriptions.

PubMed search results

PubMed: (((eclipse OR accord OR "Heatstick" OR "revo") AND cigarette AND heat* NOT (resin OR column)) OR "tobacco heating"[Title/Abstract] OR "heated cigarette*"[Title/Abstract] OR "electrically heated cigarette*"[Title/Abstract] OR "EHCSS"[Title/Abstract] OR "Electrically Heated Cigarette Smoking System*"[Title/Abstract] OR "heat* tobacco"[Title/Abstract] OR "tobacco heating cigarette*"[Title/Abstract] OR "EHCSS-K3"[Title/Abstract] OR "EHCSS-K6"[Title/Abstract] OR "heated tobacco"[Title/Abstract] OR "tobacco heating system"[Title/Abstract] OR ("heat-not-burn"[Title/Abstract] AND "tobacco"[Title/Abstract]) OR "IQOS"[Title/Abstract] OR "HEETS"[Title/Abstract] OR "heatsticks*"[Title/Abstract] OR ("heat-not-burn"[Title/Abstract] AND "tobacco"[Title/Abstract]) OR ("HNB"[Title/Abstract] AND "tobacco"[Title/Abstract]) OR ("THS"[Title/Abstract] AND "tobacco"[Title/Abstract]) OR ("Lil"[Title/Abstract] AND "tobacco"[Title/Abstract]) OR ("TEEPS"[Title/Abstract] AND "tobacco"[Title/Abstract])) OR ("Modified risk tobacco product*"[Title/Abstract]) OR ("non-cigarette combustible*"[Title/Abstract]) OR ("non combusted" AND cigarette [Title/Abstract] ) OR ("Risk continuum "[Title/Abstract] AND "tobacco"[Title/Abstract]) OR ("non-combustible” AND “tobacco"[Title/Abstract])
Scopus: ALL("tobacco W/2 heat*")OR ALL("heated tobacco product") OR ALL("heated tobacco product*") OR ALL("heated tobacco") OR ALL("tobacco heating system") OR ALL("tobacco heating system*") OR ALL("heat not burn") OR ALL(iqos) OR ALL(heets) OR ALL(heatstick*) OR ALL("electrically heated cigarette smoking system") OR ALL("electrically heated cigarette") OR ALL(ehcss) OR ALL(heat* W/2 cigarette)OR ALL("modified risk tobacco product") OR ALL("modified risk tobacco product*") OR ALL(lil W/2 tobacco) OR ALL(teeps W/2 tobacco) OR ALL(hnb AND tobacco) OR ALL("noncombustible cigarette") OR ALL("non-cigarette combustible") OR ALL("Risk continuum" AND tobacco) OR ALL(ths AND tobacco) AND NOT ALL("third hand smok*" OR "thirdhand smok*")
Embase: ths:ab AND tobacco:ab NOT ('third hand smok*' OR 'thirdhand smok*') OR (tobacco NEAR/2 heat*) OR 'heated tobacco product'/exp OR 'heated tobacco product*' OR 'heated tobacco' OR 'tobacco heating system'/exp OR 'tobacco heating system*' OR 'heat not burn' OR iqos OR heets OR heatstick* OR 'electrically heated cigarette smoking system'/exp OR 'electrically heated cigarette' OR ehcss OR (heat* NEAR/2 cigarette) OR 'modified risk tobacco product'/exp OR 'modified risk tobacco product*' OR (lil NEAR/2 tobacco) OR (teeps NEAR/2 tobacco) OR (hnb:ti,ab,kw AND tobacco:ti,ab,kw) OR 'noncombustible cigarette' OR 'non-cigarette combustible' OR ('risk continuum' AND tobacco)
Google Scholar: (“heated cigarette*”) OR (“tobacco heating”) OR ("heated tobacco") OR ("tobacco heating system") OR ("heat-not-burn" "tobacco") OR ("IQOS") OR ("HEETS") OR ("heatsticks ") OR ("heat not burn" "tobacco") OR ("THS" "tobacco") OR ("HNB" "tobacco"); Articles excluding patents ("noncombustible cigarette") OR ("non-cigarette combustible") OR ("risk continuum" "tobacco")
SciFinder: "heat not burn" OR "tobacco heating system" OR "modified risk tobacco" OR "electrically heated cigarette" OR "heated tobacco”
RightFind: "heated cigarette" or "tobacco heating" or "heated tobacco" or "tobacco heating system" or ( "heat-not-burn" and Tobacco ) or IQOS or HEETS or heatsticks or ( HNB and Tobacco ) or ( Lil and Tobacco ) or "Modified risk tobacco product" or "primarily heat tobacco" or "noncombustible cigarette" or "non-cigarette combustible'" or ( "risk continuum" and Tobacco )

Articles retrieved from these databases are screened daily by our scientific literature curator. Third-party articles are selected based on specific criteria, including publication in peer-reviewed journals and relevance to smoke-free products. Manual curation includes classifying articles by product category, study type, publication details, study sponsor funding, etc.

Additional filters exclude marketing research, PMI-supported Investigator Initiated Studies, and other PMI-sponsored studies, ensuring that our analysis focuses solely on independent scientific research.

Content Type: Journal articles
Study Sponsor / Funding: Academic, Government, Researcher, Tobacco industry, E-cigarette industry, Other industry, Association
Product Category: Heated tobacco
Study type: Original research, Original analysis, Methodology, Review, Case report
Topics: Science
Scientific disciplines: : Product Design, Aerosol Chemistry and Physics, Indoor Air Quality, Preclinical Toxicology, Clinical, Health Outcomes, Awareness and Perception, Prevalence and Use Patterns, Population Modeling

This graph shows the number of independent studies on HTPs published each year, which has significantly increased since 2017. Specific criteria for inclusion in this graph are noted above. THS was first launched in 2014 and remains the leading HTP in most markets. Because a sizeable portion of independent research focuses on the HTP category and not on THS specifically, we show here the number of publications on the HTP category.

Our analysis indicates that the most common research topics on HTPs are clinical and health outcomes, prevalence and use patterns, and aerosol science. Researchers are also active in studying preclinical toxicology and awareness and perception. Some of the studies aimed to replicate our own results, typically observing similar outcomes as we did, while significantly more studies focused on answering new research questions.

This graph shows the cumulative number of independent publications, grouped by research focus. Some publications address multiple topics and are therefore counted among multiple research areas. Not all publications fall into these categories, but they reflect the most common areas of independent research on HTPs.

Our responses to selected independent studies

Expert reports

Government health authorities’ view on heated tobacco products

Overview of government publications which touch on our Tobacco Heating System (THS) specifically, or on heated tobacco products (HTPs) in general.

Are young people using heated tobacco products?

Multiple countries report minimal heated tobacco product use among students

PMI Publications Library

Read scientific publications, presentations, and articles about our smoke-free product development and testing.

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