Particle Size Distribution Based on Mass and Number Count of Undiluted E-Cigarette Aerosols at Low Actuation Powers

MOHAMMAD SHAJID RAHMAN, Edgar Matida, Tarik Kaya, Carleton University

     Abstract Number: 67
     Working Group: Aerosol Physics

Abstract
Electronic cigarette (e-cigarette) produces inhalable aerosols by heating a liquid mixture (known as e-liquid) using battery power. Since inhaled aerosols with different sizes deposit on different regions of respiratory tract, particle size distribution (PSD) of e-cigarette aerosols demands thorough investigation to evaluate associated health hazards. Due to different limitations of measuring devices, aerosols are often diluted with air, while the PSD can be affected by the dilution process. Besides, a low heating power (e.g., less than 10 W) of e-cigarette can be beneficial in terms of a lesser production of toxic elements. However, PSD of undiluted e-cigarette aerosols at lower powers with a standard testing condition is deficient in literature. This study reports PSD of undiluted aerosols generated by a modern e-cigarette at low powers ranging from 3.5 to 6.5 W with a standard puffing topography (i.e., puff duration and flow rate of about 3 s and 1 L/min, respectively). A low-flow cascade impactor (In-Tox, 02-007) and a real-time particle counter (PSD 3603, TSI) were used to measure PSD based on mass and number count, respectively. Gravimetric measurement of PSD revealed a re-distribution of particle size towards larger particles with higher power. PSD based on particle count depicted that asymmetricity in PSD became more pronounced with power. A novel mathematical equation (a combination of exponential, Gaussian and polynomial functions) was introduced to express a wide range of asymmetric PSD. Mass median aerodynamic diameter (MMAD), count median aerodynamic diameter (CMAD) and geometric standard deviations, estimated by the two measuring methods, were compared. The values of MMAD and CMAD were within a range of 0.71 to 0.89 μm and 0.67 to 0.73 μm, respectively, when power increased from 3.5 to 6.5 W. The undiluted PSD data can be utilized in dosimetry modeling along with design improvements of related aerosol generating devices.