Independent studies

      Independent research on heated tobacco products

      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 initiated studies on smoke-free products and/or the methods/results surrounding them.

      Updated: 17 April 2024


      Heated tobacco products research landscape

      In recent years, there has been a notable surge in the number of independent organizations and institutions conducting studies on smoke-free products, including those offered by PMI, along with the methodologies and findings that support them. 

      The quantity of independent studies focusing on heated tobacco products (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 100 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 750 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 specifically dedicated to 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 approach to data collection and analysis involves utilizing RightFind, PubMed, Scopus, Embase, SciFinder, and Google Scholar scientific publication databases. This approach helps to ensure that our analysis is based on a wide range of sources and provides a robust understanding of the research landscape surrounding the topic. The collected literature covers all scientific disciplines (i.e., aerosol chemistry and physics, preclinical toxicology, and clinical and behavioral and perception studies) and beyond (i.e., policy options and marketing).  

      The resulting library is maintained and updated daily. Specific search strings are optimized for HTPs. Since some of those databases are not open access, we provide the search strings for those visitors who have access (subscriptions).

      • 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" "noncombustible cigarette" or "non-cigarette combustible'" or ( "risk continuum" and Tobacco )
      • 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 "primarily 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 ("noncombustible cigarette*"[Title/Abstract]) OR ("Risk continuum "[Title/Abstract] 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("Riskcontinuum" 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”  

      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. Articles from PMI-supported Investigator Initiated Studies and other PMI-sponsored studies are collected by the same literature search procedure.

      To ensure an accurate analysis and count of independent scientific studies, we have implemented several additional filters. These filters, for instance, exclude studies such as marketing research and those supported by PMI, 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 analysis, Methodology, Review, Case report
      • Topics: Science
      • Scientific disciplines: product design, aerosol chemistry and physics, preclinical toxicology, indoor air quality, clinical, health outcomes, population modeling, awareness and perception, prevalence and use patterns, other scientific discipline

      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 in most markets is the most common HTP on the market. 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.

      Among those studies that are focused on some aspect of our product risk assessment, many examine the THS system and/or the aerosol it creates. There are also many studies focusing on clinical results and health-related outcomes. Public awareness of the products, public perceptions about these products, the prevalence of product use, and use patterns are also of significant interest to the research community, as evidenced by the significant number of publications dedicated to those topics. 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 number of independent publications distributed by their research focus. Importantly, some publications cover multiple topics, and so are represented multiple times–once for each category they cover in this graph. Not all publications fit into these categories, but they are among the most common topics for independent research on HTPs.

      Expert reports