In order to assess the indoor air quality (IAQ) impact of products with the potential to reduce individual risk and population harm in comparison to smoking cigarettes, an environmentally controlled exposure room was built in Philip Morris International's Research & Development facility in Switzerland. An analytical platform including online and offline methods was developed, validated, and subsequently applied for several studies involving volunteer panelists. In the context of these studies, it has been repeatedly noted that it is crucial to ensure that the exposure room background conditions are properly defined when conducting experiments. Additionally, it has long been known that the presence of human beings in an enclosed environment can modify IAQ significantly by releasing several hundreds of volatile organic compounds (VOC) from breath and skin. Some of these compounds reach quantifiable levels in the air and may thus contribute to a degradation of IAQ. We therefore evaluated the impact of the number of panelists present in the exposure room and of different human activities during so-called 'activity sessions' (using heat-not-burn products, consuming alcohol, doing sport, using candles and incense, applying cosmetics, and cooking). Each activity was assessed separately using our analytical platform and exposure room under controlled environmental conditions. The results obtained showed that prolonged human presence and the indoor activities lead to an increase in the levels of selected VOCs, siloxanes as well as formaldehyde and, to a lesser extent, acetaldehyde. All of these constituents were found in higher amounts above the background level when the study participants remained for some time in the closed space of the exposure room. These learnings were applied to optimize the experimental set-up of further studies conducted to assess the IAQ impact of the use of reduced-risk products in real-life settings.