Variations in coil temperature/power and e‐liquid constituents change size and lung deposition of particles emitted by an electronic cigarette

Abstract

Electronic cigarette uses propylene glycol and glycerol to deliver nicotine and flavors to the lungs. Given the hundreds of different brands, the thousands of flavors available and the variations in nicotine concentrations, it is likely that electronic cigarette settings and e‐liquid composition affect the size distribution of particles emitted and ultimately pulmonary deposition. We used the inExpose e‐cigarette extension to study two separate modes of operation of electronic cigarettes, namely power‐controlled and the temperature‐controlled. We also assessed several e‐liquids based on propylene glycol and glycerol concentrations, nicotine content, and selected monomolecular flavoring agents (menthol, vanillin, and maltol). Particle size distribution was measured using a Condensation Particle Counter and a Scanning Mobility Particle Sizer spectrometer. Lung deposition was predicted using the International Commission on Radiological Protection model. For all resistance coils, increase in power delivery generated larger particles while maintaining a higher coil temperature generated smaller particles. Increase in glycerol concentration led to the generation of larger particles. With regard to flavors, we showed that despite minor effect of menthol and maltol, vanillin dramatically increased particle size. Presence of nicotine also increased particle size. Finally, particles emitted by the electronic cigarette were predicted to mainly deposit in the alveoli and conditions generating larger particle sizes led to a reduction in predicted lung deposition. This study shows that coil temperature, propylene glycol and glycerol concentrations, presence of nicotine, and flavors affect the size of particles emitted by an electronic cigarette, directly affecting predicted lung deposition of these particles.

The health effects of ultrafine particles

“…Highresistance coils in electronic cigarettes and increased glycerol generate larger particles, and higher coil temperatures generate smaller particles. Particles produced by the electronic cigarettes are deposited in alveoli 69 .…”

Vaping-Related Acute Parenchymal Lung Injury

“…3 Vape aerosols harbor a number of toxic substances, that include volatile organic compounds, heavy metals, and ultrafine particles. [18][19][20][21] Sporadic cases of vaping-related respiratory illnesses have been reported since 2012; however, the current outbreak did not begin until the summer of 2019. 15 Most recently implicated in 2,807 cases and 68 deaths, the EVALI outbreak has prompted the formation of a lung injury task force by the Centers for Disease Control and Prevention (CDC).…”

Modeling aerial transmission of pathogens (including the SARS-CoV-2 virus) through aerosol emissions from e-cigarettes

“…The former correspond only to inhalation times as instruments aim at simulation of a mouth inhalation, the latter are time lapses in human vapers and thus include inhalation and exhalation. [20,31,26,28], the CMD distribution of ECA as it is exhaled should be dominated by modes in intermediate ranges 0.1 − 0.5 µm. Since there are no ECA measurements at the exhalation point (the vaper's mouth), we can estimate the representative droplet diameter by a rough order of magnitude calculation: assuming an aerosol mass yield of 5 mg of inhaled ECA for a low powered device, a 90% retention of aerosol mass with 50 % made of PM, the total droplet mass of exhaled ECA should be around M p = 0.25 mg.…”

“…Count mean diameter (CMD) distributions of mainstream ECA droplets vary depending on the device, puffing style of users, flavors and nicotine content [33,37]. Droplet number count is heavily dominated by submicron droplets with CMD distributions having either single modes below 100 nm or bimodal forms (one mode well below 100 nm and one in the range 100-300 nm) [33, 37, 38, 39, 40, 41].…”

“…However, there is ambiguity in inferring a value for droplet volume concentration because of insufficient data on how much the larger tidal volume and deeper inhalation of DTL vaping can modify respiratory droplet numbers and diameters. As mentioned in section 3, higher powered devices associated with DTL vaping tend to increase ECA droplet sizes and diameters [26, 22] but it is not certain if this applies to respiratory droplets. However, as mentioned in section 7, speech involves droplet generating mechanisms that are distinct from those of breathing [91, 84, 82], resulting in higher rate of droplet emission even with a tidal volume only slightly larger than the breathing rest value of 400 − 600 cm 3 [114, 115].…”