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 (PM_2.5) 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 PM_2.5 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. PM_2.5 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.

The benefit of electronic cigarettes (e-cigarettes) in smoking cessation remains controversial. Recently, e-cigarettes have been gaining popularity in Japan, without evidence of efficacy on quitting cigarettes. We conducted an online survey to collect information on tobacco use, difficulties in smoking cessation, socio-demographic factors, and health-related factors in Japan. Among the total participants (n = 9055), 798 eligible persons aged 20–69 years who smoked within the previous five years were analyzed to assess the relationship between the outcome of smoking cessation and quitting methods used, including e-cigarettes, smoking cessation therapy, and unassisted. E-cigarette use was negatively associated with smoking cessation (odds ratio (OR) = 0.632; 95% confidence interval (CI) = 0.414–0.964) after adjusting for gender, age, health-related factors, and other quitting methods. Conversely, smoking cessation therapy (i.e., varenicline) was significantly associated with smoking cessation (OR = 1.885; 95% CI = 1.018–3.492) in the same model. For effective smoking cessation, e-cigarette use appears to have low efficacy among smokers in Japan. Allowing for the fact that this study is limited by its cross-sectional design, follow-up studies are needed to assess the prospective association between e-cigarette use and smoking cessation.