THS

    Tobacco Heating System

    Our Tobacco Heating System (THS), commercialized by Philip Morris International (PMI) under the IQOS brand, heats tobacco instead of burning it. This is done via an electronically controlled system using either internal resistive or internal induction heating technology. These products have been scientifically substantiated to reduce exposure to harmful chemicals emitted by tobacco combustion. Learn more about how these products work.

    What is the THS?

    The THS is a heated tobacco product (HTP), also known as heat-not-burn (HnB) product, which heats tobacco just enough to release a nicotine-containing tobacco aerosol without burning, unlike cigarettes. Because tobacco is heated and not burned, there is no smoke and the levels of harmful chemicals in the generated aerosols are significantly reduced compared with cigarette smoke. However, HTPs are not risk free, and they provide nicotine, which is addictive. But for adult smokers who don’t quit, they are a better alternative than continued smoking.

    Our THS is the most developed and most thoroughly assessed of our HTPs. We have accumulated extensive clinical and nonclinical data to support its potential to reduce the risk of developing smoking-related diseases compared with continued cigarette smoking.

    What are the different types of PMI’s THS products?

    PMI’s THS includes two product versions based on different heating technologies: internal resistive and internal induction. Initial generations of our THS, known as THS 2.2 or blade THS, and commercialized as IQOS 3 or IQOS Originals, use a blade to heat the tobacco through internal resistive heating. These are designed to be used with specific heated tobacco units (HTUs), or heatsticks, commercialized under the name HEETS.

    We later developed the next version of our THS, known as THS 3.0 or induction THS, and commercialized as IQOS ILUMA. It features internal induction heating technology and uses specially designed HTUs, commercialized under the name TEREA. 

    Despite the changes in heating technology, the aerosol generated by our resistive and induction heating technologies remains comparable across all THS product versions.

    In addition, we have developed nicotine-containing heated units for the induction THS that do not contain tobacco, commercialized as LEVIA. When heated, they provide a tobacco-free, nicotine-containing aerosol. 

    How do our blade THS devices work? 

    When the HTU is inserted into the holder, the heating blade embedded inside the holder pierces the tobacco plug of the HTU in the middle. Once activated, the heating blade heats the tobacco plug from the inside while also monitoring its temperature, to ensure consistent taste and avoid burning. 

    The blade THS is also available in an all-in-one variant, maintaining the same operating principle. Unlike the classic three-component design, which consists of a charger, a holder, and the HTU, and which typically allows for two consecutive uses, the all-in-one variant integrates the holder and charger into a single unit while enabling more consecutive uses.

    How do our induction THS devices work?

    The THS using internal induction heating technology, also known as induction THS, offers a different approach to heating tobacco compared with the blade technology. With this version, there is no direct contact between the electronics and the heating element.

    The induction heating technology relies on specially designed HTUs, each with their own internal heating element, called susceptor, at their core. When the HTU is placed inside the holder, the system is automatically activated and an electric current flows through the coil in the holder. This current creates a magnetic field that heats up the susceptor inside the tobacco plug, which in turn heats the surrounding tobacco.

    As with the blade THS, the induction THS also comes in an all-in-one variant, which still shares the same operating principles as the classic three-component design (charger, holder, and HTU), but combines the holder and charger into a single unit while allowing for more consecutive uses.

    Watch the video* to see the induction HTP in action:

    *"Platform 1" in this video refers to the induction version of THS.

    In March 2024, a new model of induction THS, commercialized as IQOS ILUMA i, was launched in Japan. It offers the most flexible and adaptive experience thanks to the implementation of three advanced device functionalities:

    • FlexPuff: Allows more than 14 puffs for users who take small puffs.
    • Pause Mode: Enables users to pause their experience and resume it later.
    • FlexBattery Modes: Optimizes the holder’s battery energy consumption or increases the battery's lifespan.

    What are HTUs? 

    HTUs are single-use units that contain a uniquely processed tobacco plug specially designed for to be heated with THS. Each version of THS uses a different type of HTU, intended to be used with their corresponding heating technology (blade or induction). 

    The tobacco plug is made from tobacco leaves, which are ground and reconstituted into tobacco sheets, called cast-leaf. For units designed to be used with our blade devices, these sheets are then crimped and formed into rods. The rods are cut to the necessary length and combined with the other components, such as the mouthpiece filter and the hollow acetate tube. The entire unit is wrapped in an outer paper to form a completed unit.

    For HTUs used with our induction THS, the tobacco plug is protected by a front plug, while the susceptor is incorporated into the center of the tobacco plug.

    What is LEVIA?

    LEVIA is the commercial name of our heated unit that contains nicotine but does not contain tobacco. It is designed to be used exclusively with our induction THS.

    Instead of tobacco, the core of the stick is made up of ingredients primarily derived from cellulose-based materials, carefully processed to act as a neutral carrier without additional aromas. This allows us to apply flavors and nicotine into the stick.

    Although these heated units do not contain tobacco, they are not risk free and provide nicotine, which is addictive. 

    The science behind THS

    PMI has scientifically demonstrated that during the operation of THS—independent of which product version is considered—no combustion occurs, and the aerosol generated emits on average 95% lower levels of harmful and potentially harmful constituents (HPHCs), compared with cigarettes. However, this does not necessarily equal a 95% reduction in risk. The THS is not risk free and contains nicotine, which is addictive. But for adult smokers who don’t quit, it is a better alternative than continued smoking.

    A number of public health organizations, including the U.S. Food and Drug Administration (FDA) have reviewed our scientific evidence package regarding THS. On July 7, 2020, the FDA authorized the marketing of the blade THS  as a Modified Risk Tobacco Product (MRTP) with reduced exposure information in the U.S. The order letters and decision summaries are available on the FDA’s website. These orders apply to IQOS 2.4 as of July 2020 and IQOS 3 as of March 2022, but do not apply to all versions of the IQOS  system. 

    The approach used by PMI to substantiate reduced emissions for consumer-facing product statement is based on the World Health Organization (WHO) 9 list. This is a list of nine priority HPHCs proposed by the WHO Study Group on Tobacco Product Regulation for mandated lowering in cigarette smoke, which does not include nicotine.  

    PMI selected the WHO 9 because it allows us to provide consumers with accurate and nonmisleading information while improving the consistency of the messages across product categories and aligning with industry practices. Furthermore, this approach enables consumers to make educated and informed decisions about the products available on the market, including product properties, benefits, and risks.

    The totality of evidence so far demonstrates that the THS is a better choice for adult smokers who would otherwise continue smoking cigarettes and that switching completely to THS presents less risk of harm than continued smoking.

    You can find a summary of our entire product assessment program in the PMI Science Booklet, and our publications, most of which are open access, can be found via the publications library.

    How our heated tobacco products evolved
    THS

    Over 30 years of innovation

    Explore the 30 years of innovation behind our leading heated tobacco product, THS. Read key information on each iteration, and learn how the user experience, heating technology, and battery technology have evolved over time.

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    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. All of our RRPs are smoke-free products that deliver nicotine with far lower quantities of harmful and potentially harmful constituents than found in cigarette smoke.