Philip Morris International (PMI) is developing products with the potential to reduce the risk associated with smoking. The Tobacco Heating System (THS 2.2) operates by heating tobacco rather than burning it and results in an aerosol with substantially lower levels of harmful or potentially harmful constituents when compared to combustible cigarette (CC) smoke. Additionally, THS 2.2 does not produce sidestream aerosol in the same manner as CC, since aerosol is only generated when puffs are taken. Thus, the impact on air quality of using THS 2.2 indoors is expected to be very different to CC. To verify this hypothesis, PMI built an environmentally controlled, furnished room and developed analytical methods to measure air pollutants under diverse simulated indoor environments focusing on: (i) ISO measurement standards for Environmental Tobacco Smoke and, (ii) selected carbonyls and volatile organic compounds.A study was conducted with 3 simulated conditions (office, hospitality, residential) with conditions defined according to CEN standard EN 15251:2007. Three test items were compared: CC (Marlboro Gold 6 mg), THS 2.2 and background (measured with people in the room without product use). Each study was duplicated, resulting in 18 separate sessions in total, each with a duration of 5 hours, with 4 hours of sample collection. For each analyte and condition, THS 2.2 and CC measured levels were compared to background levels. In case of statistical equivalence, no impact on air quality is reported. When levels are statistically above background, the levels are adjusted by subtraction of the background and reported (in mass per cubic meters).For CC, all analytes for the 3 conditions were above background. For THS 2.2, no difference was detected between background and THS 2.2 for fifteen of the eighteen analytes investigated, irrespective of the environmental conditions applied. For the 3 analytes that were demonstrated to be statistically increased between THS 2.2 and background (nicotine, acetaldehyde and nitric oxides), the levels measured for THS 2.2 were only slightly increased compared to the background, 1 or 2 orders of magnitude lower than those measured for CC. Keywords: E-cigarette, Methodology.