Effect of electronic cigarette (EC) aerosols on particle size distribution in indoor air and in a radon chamber

Abstract

Particle size distribution is an important factor governing whether aerosols can be deposited in various respiratory tract regions in humans. Recently, electronic cigarette (EC), as the alternative of tobacco cigarette, has become increasingly popular all over the world. However, emissions from ECs may contribute to both indoor and outdoor air pollution; moreover, comments about their safety remain controversial, and the number of users is increasing rapidly. In this investigation, aerosols were generated from ECs and studied in the indoor air and in a chamber under controlled conditions of radon concentration. The generated aerosols were characterized in terms of particle number concentrations, size, and activity distributions by using aerosol diffusion spectrometer (ADS), diffusion battery, and cascade impactor. The range of ADS assessment was from 10−3 μm to 10 μm. The number concentration of the injected aerosol particles was between 40 000 and 100 000 particles/cm3. The distribution of these particles was the most within the ultrafine particle size range (0–0.2 μm), and the other particle were in the size range from 0.3 μm to 1 μm. The surface area distribution and the mass size distribution are presented and compared with bimodal distribution. In the radon chamber, all distributions were clearly bimodal, as the free radon decay product was approximately 1 nm in diameter, with a fraction of ~0.7 for a clean chamber (without any additional source of aerosols). The attached fraction with the aerosol particles from the ECs had a size not exceeding 1.0 μm.

Attachment rate characteristics of different wide used aerosol sources in indoor air

“…This was deployed to measure the number size distributions of particles from the nanometer to the micrometer size ranges (from 5 nm to 10 μm). Aerosol particle parameters like concentration, average particle surface area, number size distribution, and metrological parameters (temperature, humidity and pressure) were recorded and automatically saved every ~1 min [37,[49][50][51][52][53].…”

Dynamic of Particulate Matter for Quotidian Aerosol Sources in Indoor Air

“…A diffusion aerosol spectrometer (DAS) was used to monitor mass concentrations continuously before the aerosol source was turned on (BG), during the time it was on and at intervals after it was switched off. The technical design and the description of the DAS (Model 2702 M) are presented in previous works [43][44][45][46][47][48].…”

“…With a confirmed negative impact on human health, scientists divided particles into fine (diameter >100 nm) and ultrafine particles (diameter <100 nm). Ultrafine particles can penetrate deep into the respiratory system and even cross biological barriers, leading to harmful health effects due to their small size [34][35][36][37][38][39][40][41][42][43][44][45][46][47][48]. Therefore, a precise characterization of multiple parameters for fine and ultrafine particles is required [42,49].…”

Radon and Its Short-Lived Products in Indoor Air: Present Status and Perspectives

“…Average values of number aerosol concentration (N/mm −3 ), the geometric mean of particle diameter (d GM /nm), the concentration of potential α-energy of attached (E a αRnP /MeV cm −3 ) and unattached radon short-lived products (E u αRnP /MeV cm −3 ), and their equilibrium factor (F Rn ), as measured before and at the end of 12 min of 'smoking' traditional and electronic cigarettes in the radon chamber (at 1.6 kBq m −3 radon concentration) at INMRI-ENEA, Rome, Italy; the last row shows the ratio between the maximum and background values by Vargas Trassierra et al [63]. Another experiment [237] shows the effect of the aerosol particles from smoking an electronic cigarette on the particle size distribution in indoor air and air in a radon chamber. Activity size distributions are clearly bimodal, with modes corresponding to the unattached RnP and RnP attached to the smoke particles of the electronic cigarette.…”