Heated tobacco products (HTPs) and electronic cigarettes (ECs) represent a potentially less harmful alternative to traditional tobacco products, such as conventional cigarettes (CCs), with growing popularity amongst adult smokers worldwide. Their users exhale a very dynamic aerosol to indoor air which undergoes rapid transformations. In the present study, we assessed the dynamics of the generated exhaled aerosols following use of a new HTP (branded as “Pulze”, operating in eco and standard modes) and an e-cigarette (“myblu”) in a chamber environment by three volunteers, controlling for the distance to bystander, ventilation intensity and microclimate. The HTP and EC data was compared against conventional cigarette data. HTP generally resulted in lower aerosol number concentration during puffs reaching 1.66E+06 # cm–3 at 0.5 m from bystander, compared to EC (averaging 4.3E+06 # cm–3), and CC (1.47E+08 # cm–3). No significant difference was observed between “eco” and “standard” modes of HTP. At the same time, EC concentration decrease after puffs was also faster, indicating higher volatility of particles. EC also featured higher mode during puff (120 nm) compared to HTP (90 nm), which was significantly different from conventional cigarette (165–200 nm). The evaporation/shrinkage of particles has been observed within 10 s after puff with the HTP and EC. Distance to a bystander was shown to be as a significant factor affecting aerosol dynamics, however ventilation intensity and relative humidity did not have statistically significant effect.