It is too early to provide a clear answer on the impact of exposure to the second-hand aerosol of heated tobacco products (HTPs) in the planning of policy for smoke-free indoors legislation. Here, we conducted a preliminary study to evaluate indoor air quality with the use of HTPs. We first measured the concentration of nicotine and particulate matter (PM2.5) in the air following 50 puffs in the use of HTPs or cigarettes in a small shower cubicle. We then measured these concentrations in comparison with the use equivalent of smoking 5.4 cigarettes per hour in a 25 m3 room, as a typical indoor environment test condition. In the shower cubicle test, nicotine concentrations in indoor air using three types of HTP, namely IQOS, glo, and ploomTECH, were 25.9-257 μg/m3. These values all exceed the upper bound of the range of tolerable concentration without health concerns, namely 3 µg/m3. In particular, the indoor PM2.5 concentration of about 300 to 500 μg/m3 using IQOS or glo in the shower cubicle is hazardous. In the 25 m3 room test, in contrast, nicotine concentrations in indoor air with the three types of HTP did not exceed 3 μg/m3. PM2.5 concentrations were below the standard value of 15 μg/m3 per year for IQOS and ploomTECH, but were slightly high for glo, with some measurements exceeding 100 μg/m3. These results do not negate the inclusion of HTPs within a regulatory framework for indoor tolerable use from exposure to HTP aerosol, unlike cigarette smoke.
Keywords: exposure assessment; heated tobacco products (HTPs); nicotine; particulate matter 2.5 (PM2.5); policy; secondhand aerosol.