Characteristics of secondhand electronic cigarette aerosols from active human use

摘要

The electronic cigarette (EC) is a new source of indoor airborne particles. To better understand the impacts of secondhand vaping (SHV) emissions on indoor air quality, real-time measurements of particle size distribution, particle number concentration (PNC), fine particulate matter (PM2.5), CO2, CO, and formaldehyde were conducted before, during, and after 10 min EC-use among 13 experienced users in an 80 m(3) room. To assess particle transport in the room, multiple sampling locations were set up at 0.8, 1.5, 2.0, and 2.5 m away from the subjects. The arithmetic mean (standard deviation) of background PNC and PM2.5 concentrations in the room were 6.39 x 10(3) (1.58 x 10(2)) particles/cm(3) and 8 (1) mg/m(3), respectively. At 0.8 m away from EC users, right after initiation of puffing, the PNC and PM2.5 concentrations can reach a peak of similar to 10(5) particles/cm3 and similar to 3 x 10(3) mu g/m(3), respectively, and then dropped quickly to background levels within 20 s due to dilution and evaporation. At the 0.8 m sampling location, the mean PNC and PM2.5 concentrations during puffing were 2.48 x 10(4) (2.14 x 10(4)) particles/cm3 and 188 (433) mu g/m(3), respectively. In addition, two modes of SHV particles were observed at about 15 and 85 nm. Moreover, concentrations of SHV particles were negatively correlated with the distances to EC users. At the 1.5 m location, PNC and PM2.5 levels were 9.91 x 10(3) (1.76 x 10(3)) particles/cm(3) and 19 (14) mu g/m(3), respectively. Large variations of mean PNC levels exhaled per puff were observed both within and between EC users. Data presented in this study can be used for SHV particle exposure assessment.