Puff Duration Research Articles

Waterpipe size matters: the effect of waterpipe size on toxicant exposures and subjective experiences.

Waterpipe (WP) tobacco smoking remains popular among US young adults, yet specific regulations for WP devices are lacking. This study examines how WP device size (base volume and height) affects smoking behavior, toxicant exposures, and subjective experiences. Thirty-eight individuals who smoke WP aged 21 to 39 participated in a randomized crossover study. Each completed three 45-minute ad libitum smoking sessions using small, medium, and large WP sizes. Saliva nicotine and exhaled carbon monoxide (eCO) were measured before and after smoking. Puff topography was recorded during sessions, and subjective smoking experiences were collected afterward. Significant differences were observed in saliva nicotine between the three WP sizes, with higher concentrations for the small WP relative to larger sizes (Ps<0.05). Exhaled CO was significantly higher after smoking the large WP compared to smaller sizes (Ps<0.05). Puff topography revealed significant differences and followed a dose-response pattern, with larger size associated with longer puff duration, greater smoke volume inhaled, and larger puff volume (Ps<0.05). The large WP was associated with enhanced subjective experiences for satisfaction and concentration compared to the small WP (Ps<0.05). WP size substantially impacts smoking experiences and exposures. Regulation of WP size should be essential in comprehensive tobacco control policies aimed at curbing WP use among young adults. These findings will aid in developing of WP size-specific standards to regulate the marketing and sales of WP devices. Such regulations should aim to minimize toxicant exposure by controlling the dimensions and design of WP components, which can significantly influence smoking behavior and toxicant intake. This study underscores the critical role of waterpipe (WP) size in shaping smoking behavior, experiences, and exposures among young adults.

Assessment of human abuse potential of an unflavored, sucralose-sweetened electronic cigarette in combustible cigarette smokers.

Despite the popularity of electronic cigarettes (ECIGs), limited research has examined the role of sweeteners, independent of other flavors, in shaping ECIG human abuse potential (HAP). This study examined the effects of sucralose and nicotine in unflavored ECIG liquid solutions to provide a basic understanding of the effects of sweeteners on ECIG HAP compared to combustible cigarettes. Individuals who smoked cigarettes daily (N = 14) completed five within-subject, Latin-square ordered study sessions that differed by product used: (a) own-brand combustible cigarettes (OB), (b) 0 mg/mL nicotine, unsweetened liquid, (c) 0 mg/mL nicotine, sucralose-sweetened liquid, (d) 15 mg/mL nicotine, unsweetened liquid, and (e) 15 mg/mL nicotine, sucralose-sweetened liquid. Participants completed subjective questionnaires and behavioral tasks following a 10-puff directed use bout during which puff topography was measured, and blood was sampled for later measurement of plasma nicotine concentration. On average, the OB condition had a greater increase in plasma nicotine concentration and produced more pronounced subjective effects compared to the ECIG conditions. The 15 mg/mL nicotine ECIGs delivered significantly more nicotine and produced greater drug effects and reductions in tobacco abstinence symptoms than the 0 mg/mL nicotine ECIGs. Sucralose-containing solutions increased ECIG product appeal, puff duration, and puff volume during the 10-puff directed bout. Findings revealed greater HAP for OB cigarettes relative to all ECIGs tested and suggest that adding sucralose and nicotine elevates ECIG HAP via different mechanisms; sucralose appears to influence HAP through product appeal, while nicotine influences HAP through drug effects and tobacco/nicotine abstinence symptom suppression. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Simulation of electronic nicotine delivery systems (ENDS) aerosol dosimetry and nicotine pharmacokinetics

Electronic nicotine delivery systems (ENDS) heat a liquid solution typically containing propylene glycol, vegetable glycerin, water, nicotine, and flavor chemicals to deliver an aerosol to the user. ENDS aerosols are complex, multi-constituent mixtures of droplets and vapors. Lung dosimetry predictions require mechanistic models that account for the physico-chemical properties of the constituents and thermodynamic processes of the aerosol as it travels through the respiratory tract and deposits in lung airways. In this study, a model formulated to predict ENDS aerosol deposition in the oral cavity and lung airways was linked with a physiologically-based pharmacokinetic (PBPK) model to predict nicotine pharmacokinetics (PK) as a function of product characteristics and puff topography. Predicted plasma nicotine PK compared favorably with available experimental data and captured the rapid increase in plasma levels followed by a clearance phase after ENDS use. E-liquid nicotine concentration and puff duration substantially increased nicotine lung deposition and plasma nicotine levels. Increasing the puff duration from 1 to 5 s while assuming a constant aerosol flow rate resulted in an ∼5-fold increase in nicotine lung deposition (45.0 µg to 243.7 µg) and increased maximum plasma nicotine concentrations from 4.7 ng/mL to 25.0 ng/mL; increasing the e-liquid nicotine concentration from 1 % to 5 % yielded increases in nicotine lung deposition (41.0 µg to 204.5 µg) and maximum plasma nicotine concentration (4.2 ng/mL to 21.1 ng/mL). Model predictions demonstrate the sensitivity of ENDS aerosol lung deposition and plasma nicotine profiles to user behavior and allow for quantification of constituent deposition and nicotine absorption after ENDS use.

Partial Nicotine Reduction and E-Cigarette Users’ Puffing Behaviors Among Adults Aged 21 to 35 Years

The advent of salt-based, high-nicotine electronic nicotine delivery systems [e-cigarettes] has contributed to their epidemic use among young people in the US, necessitating the need for policies to address the addictiveness of these products. To evaluate the effect of partial nicotine reduction on new-generation e-cigarette users' puffing behaviors. This randomized crossover clinical trial was conducted at the Clinical Research Lab for Tobacco Smoking at Florida International University in Miami between April 15, 2022, and October 17, 2023. Using a volunteering sampling method by distributing flyers and advertisements, current e-cigarette users (who preferred 5% nicotine concentration), aged 21 to 35 years, were included. In a crossover design, participants completed 2 sessions of the same product (JUUL or NJOY) that differed by nicotine concentration (3% [JUUL] or 2.4% [NJOY] and 5% [JUUL or NJOY]) in random order. In each session, participants vaped up to 60 minutes ad libitum, preceded by 12 hours of nicotine abstinence. The primary outcomes were puffing topography parameters (eg, total session time, puffing time, total puffing number, interpuff interval, total inhaled volume, average puff volume, duration, and flow rate) measured during each session and plasma nicotine measured before and after each session. Among 735 participants who were approached for eligibility, 675 were excluded, and 10 did not complete session 2. Of the 50 remaining current e-cigarette users (mean [SD] age, 23 [3] years; 56% men), 23 (46%) were low nicotine dependent. The median topography parameters were significantly higher during the e-cigarette use sessions with 3% or 2.4% nicotine concentration compared with 5% nicotine concentration for 3 outcomes: puffing time (1.3 minutes [IQR, 0.3-9.4 minutes] vs 1.2 minutes [IQR, 0.2-5.6 minutes]; P = .02), puff duration (2.6 seconds [IQR, 0.8-6.9 seconds] vs 2.4 seconds [IQR, 0.4-6.6 seconds]; P = .02), and total inhaled volume (1990.0 mL [IQR, 279.0-24 400.0 mL] vs 1490.0 mL [IQR, 148.0-14 300.0 mL]; P = .05). The median plasma nicotine boost observed in the 5% nicotine concentration condition (0.0060 mg/L [IQR, 0.0001-0.0249 mg/L]) was significantly higher than that in the 3% or 2.4% session (0.0043 mg/L [IQR, 0.0008-0.0225 mg/L]) (P = .001). Additionally, deeper puffing (increased average puff duration and average puff volume) was observed in participants with higher nicotine dependence (1.42 seconds [95% CI, 1.12-1.80 seconds]; P = .03) and male users (1.38 mL [95% CI, 1.09-1.75 mL]; P = .04) in response to nicotine reduction. This randomized crossover clinical trial provides direct evidence that partial nicotine reduction in salt-based e-cigarettes was associated with acute compensatory puffing and the potential for increased exposure to toxicants. However, given the reduced nicotine delivery associated with nicotine reduction, the acute compensatory response observed in this study may not preclude a population benefit due to the marketing of less addictive products. These results suggest that at least for current e-cigarette users, partial nicotine reduction can lead to enhanced exposure to some toxicants in the short term. ClinicalTrials.gov Identifier: NCT05205382.

Constraining electronic nicotine delivery systems (ENDS) nicotine dose by controlling nicotine flux at a limited puff duration.

Nicotine flux, the rate of electronic nicotine delivery system (ENDS) nicotine emission, is important in determining ENDS abuse liability. However, flux does not account for user behavior, including puff duration. Along with nicotine flux, puff duration limits the dose of nicotine that can be inhaled. Controlling both flux and puff duration allows regulators to constrain nicotine dose effectively. This study examined the effects of differing ENDS nicotine fluxes (by manipulating liquid nicotine concentration and holding device power constant), with user puff duration limited to 2 s. Participants (N = 32) completed four sessions, each session differing by nicotine flux (no flux, low flux, cigarettelike flux, and high flux conditions). Participants completed two ENDS use bouts in each session while puff duration was limited to 2 s. Plasma nicotine concentration, heart rate, and subjective effects were measured. At higher flux, higher plasma nicotine concentration and higher heart rate were observed. Moreover, higher fluxes decreased ratings of craving and urge to use nicotine and increased positive subjective effects, such as calmness. This study demonstrates that by manipulating nicotine flux and limiting puff duration, nicotine dose can be controlled. Subsequent research should demonstrate the effects of manipulating puff duration systematically. Results underscore the importance of targeting both flux and puff duration for ENDS regulation, intended to reduce abuse liability while maintaining the potential to facilitate transitions from cigarettes to ENDS. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Supplemental Material for Constraining Electronic Nicotine Delivery Systems (ENDS) Nicotine Dose by Controlling Nicotine Flux at a Limited Puff Duration

Supplemental Material for Constraining Electronic Nicotine Delivery Systems (ENDS) Nicotine Dose by Controlling Nicotine Flux at a Limited Puff Duration

The Effects of Changes in Cigarette Menthol Content on Acute Nicotine Pharmacology and Smoking Topography.

Menthol influences the appeal and addictiveness of cigarette smoking, however the data regarding menthol's effects on nicotine pharmacokinetics (PK) and smoking topography are inconsistent. This study investigated the impact of different cigarette menthol levels on nicotine pharmacology and smoking topography in current menthol smokers. The study was a double-blind, randomized, four-period, crossover study to investigate the effects of smoking cigarettes with varying menthol content (0, 3, 6, and 12mg menthol) on nicotine PK, smoking topography, and subjective effects in current menthol smokers. Each experimental session consisted of a prescribed use session, followed by 145min of no smoking and a 1-h ad libitum smoking session. Serial blood samples were collected; smoking topography was recorded using CReSS Lab topography device. There was no significant effect of menthol on nicotine PK after prescribed smoking of cigarettes with varying menthol contents. During ad libitum smoking, there was significantly smaller total puff volume and puff duration in the 12mg menthol condition compared to other menthol conditions. Subjective and sensory measures indicated significantly higher overall positive ratings for the 3mg and 6mg menthol cigarettes compared to the 0mg menthol cigarette; the 12mg menthol cigarette was less liked and harsher than the 3mg condition. These findings suggest that menthol, at concentrations reflecting the marketplace (3-6mg), contributes to positive subjective smoking experiences among menthol smokers, but does not have a significant effect on nicotine PK or smoking topography in an acute laboratory setting. While our data indicate that varying menthol content does not have a significant impact on nicotine's pharmacological effects under acute exposure conditions, these data highlight the contribution of menthol's flavor and sensory effects to product preference and positive smoking experiences, which facilitate repeated experimentation, progression to regular use, and subsequent dependence.

Switching people who smoke to unfiltered cigarettes: Effects on smoking topography

IntroductionSmoking topography (ST) describes smoking behavior and patterns. Removal of the cigarette filter and subsequent impact on ST has not been investigated. This is the first clinical trial comparing ST for filtered and unfiltered cigarettes in a naturalistic experiment. MethodsWe conducted a crossover clinical trial following established people who smoke cigarettes (n = 32) for two weeks under filtered and unfiltered smoking experimental conditions. Participants (50 % female, mean age 38.3 yr.) smoked in each experimental condition followed by a 3-week post-washout period. ST (puff count, volume, duration, peak and average flow) was measured at six time-points. Statistical analysis included a linear repeated mixed-effects model of smoking experimental conditions by visit number and sex. ResultsAverage flow (ml/sec) was significantly less for filtered smoking (−6.92 lower (95 % CI: −13.44 to −0.39), p < 0.05), thus demonstrating more resistance on inhalation. No significant differences were found between filtered or unfiltered experimental conditions for other ST variables. However, average volume and average peak flow were somewhat higher in unfiltered smoking, and lower mean puff counts/cigarette were observed for unfiltered compared to filtered smoking. ConclusionLower average flow rates were associated with filtered cigarette smoking. No significant differences were found for other ST variables between smoking experimental conditions. ST measurements comparing cigarette smoking conditions may determine if product regulatory changes, such as removing the cigarette filter could impact smoking behavioral patterns among people who smoke. This proof-of-principle study measuring ST may be replicated in larger trials to determine potential behavioral changes in smoking unfiltered cigarettes.

Study of waterpipe smoking topography in Fars province of Iran

Despite a sharp increase in the use of the waterpipe (WP) has been noted recently in Iran, no information is available for the smoking behavior and topography parameters. The present study is intended to obtain the inhalation and smoking topography parameters for the Iranian WP smokers. The smoking data collected from 122 smoking sessions, including 192 WP smokers in the Iranian Fars province have been used to perform smoking topography assessments. The influence of demographic and smoking parameters on puffing data is obtained. Results have indicated that gender and tobacco type strongly affect puff volume and duration. Women smokers inhale smaller volume of smoke than men and puff duration is significantly increased for regular smokers than occasional smokers. However, the results of the present study have not revealed a major effect of age, residence and setting on the puffing behavior.

Exposure to Electronic Waterpipes Increases the Risk of Occlusive Cardiovascular Disease in C57BL/6J Mice.

It is well documented that cardiovascular disease (CVD) is the leading cause of death in the US and worldwide, with smoking being the most preventable cause. Additionally, most smokers die from thrombotic-based diseases, in which platelets play a major role. To this end, because of the proven harm of smoking, several novel tobacco products such as electronic(e)-waterpipe have been gaining popularity among different sectors of the population, partly due to their "false" safety claims. While many investigators have focused on the negative health effects of traditional cigarettes and e-cigarettes on the cardiovascular system, virtually little or nothing is known about e-waterpipes, which we investigated herein. To investigate their occlusive CVD effects, we employed a whole-body mouse exposure model of e-waterpipe vape/smoke and exposed C57BL/6J male mice (starting at 7 weeks of age) for 1 month, with the controls exposed to clean air. Exposures took place seven times a week, according to the well-known Beirut protocol, which has been employed in many studies, as it mimics real-life waterpipe exposure scenarios; specifically, 171 puffs of 530 ml volume of the e-liquid at 2.6 s puff duration and 17 s puff interval. The e-waterpipe exposed mice had shortened bleeding and occlusion times, when compared to the clean air controls, indicating a prothrombotic phenotype. As for the mechanism underlying this phenotype, we found that e-waterpipe exposed platelets exhibited enhanced agonist-triggered aggregation and dense granule secretion. Also, flow cytometry analysis of surface markers of platelet activation showed that both P-selectin and integrin GPIIb-IIIa activation were enhanced in the e-waterpipe exposed platelets, relative to the controls. Finally, platelet spreading and Akt phosphorylation were also more pronounced in the exposed mice. We document that e-waterpipe exposure does exert untoward effects in the context of thrombosis-based CVD, in part, via promoting platelet hyperreactivity.

Mechanism of cytotoxicity induced by the cigarette smoke extract (CSE) of heated tobacco products in vascular smooth muscle cells: A comparative study of the cytotoxic effects of CSE and the ferroptosis inducer, erastin

Heated tobacco products (HTPs) are marketed worldwide as less harmful alternatives to combustible cigarettes; however, their cytotoxic mechanisms in vascular smooth muscle cells are poorly understood. Ferroptosis is defined as iron-dependent cell death caused by the accumulation of lipid peroxidation products. In this study, the cytotoxic effects of nicotine- and tar-free cigarette smoke extracts (CSE) derived from three types of HTPs and the ferroptosis inducer, erastin, on vascular smooth muscle A7r5 cells were compared. Cigarette smoke from all HTPs was generated according to the following puffing regime: 55 mL, puff volume; 30 s, puff interval; 2 s, puff duration; bell-shaped, puff profile; and no blocking of the ventilation holes. Erastin and CSE decreased mitochondrial metabolic activity and increased lactate dehydrogenase leakage. The cytotoxic effects of erastin were almost completely inhibited by the radical-trapping antioxidant, UAMC-3203; iron chelator, deferoxamine mesylate (DFO); 12/15-lipoxygenase (12/15-LOX) inhibitor, baicalein; and selective 15-LOX inhibitor, ML351. In contrast, CSE-induced cell damage was partially attenuated by UAMC-3203, baicalein, and ML351 but not by DFO. These results suggest that erastin induces ferroptosis via 15-LOX-mediated iron-dependent lipid peroxidation, whereas CSE causes iron-independent cell damage via 15-LOX-mediated lipid peroxidation-dependent and -independent mechanisms.

Influence of nicotine form and nicotine flux on puffing behavior and mouth-level exposure to nicotine from electronic nicotine delivery systems

BackgroundNicotine form (freebase/protonated) and nicotine flux (rate at which nicotine is emitted) are two factors that can affect the dose of nicotine inhaled by individuals using electronic nicotine delivery systems (ENDS) because they can influence puffing behavior. The nicotine dose for each puff also is directly proportional to nicotine flux (i.e., dose/puff=nicotine flux*puff duration). This study examines the effect of nicotine form and flux on puffing parameters and mouth-level nicotine exposure. MethodsThirty-two dual ENDS and combustible cigarette participants completed five visits that differed by nicotine form (freebase or protonated) and nicotine flux (14 or 35µg/sec); a zero-nicotine condition was a negative control. Participants used a Subox Mini C ENDS, powered at 20W, during a 10-puff directed bout (B1) followed by a one-hour ad libitum bout (B2). Puffing parameters and mouth-level nicotine exposure were assessed using the American University of Beirut REALTIME instrument. ResultsRelative to protonated nicotine, freebase nicotine was associated with lower total puff duration (puff duration*number of puffs), lower flow rate in B1, lower liquid consumption, and lower mouth-level nicotine exposure. Increasing nicotine flux from 14 to 35µg/sec was associated with lower total puff duration in both bouts, as well as lower liquid consumption. Increasing nicotine flux was associated with higher mouth-level nicotine exposure in B1 only. ConclusionENDS with protonated nicotine may enhance nicotine exposure by promoting longer puffing and thus greater dose delivered. This work highlights the importance of accounting for interactions between nicotine form and flux when considering nicotine regulation for ENDS.

Impact of More Intense Smoking Parameters and Flavor Variety on Toxicant Levels in Emissions of a Heated Tobacco Product.

IQOS HEETS are promoted as reduced-risk alternatives to cigarettes. Although some studies have investigated the chemical composition of HEETS emissions, little is known on whether toxicant levels in such emissions are affected by different puffing parameters and flavor varieties. This has important implications when assessing actual human exposure, since IQOS users develop a specific and personalized puffing behavior and may use different HEETS variants. This study measured the levels of nicotine, total particulate matter, carbonyl compounds, and tobacco-specific nitrosamines (TSNAs) in the emissions of nine differently flavored HEETS and two cigarettes (1R6F and Marlboro Red, MR). Emissions from Yellow HEETS, 1R6F, and MR were collected using the World Health Organization Intense smoking regime and four more intense smoking regimes. Yellow HEETS aerosol contained lower levels of toxicants compared to 1R6F and MR smoke. More intense smoking regimes increased carbonyl release in cigarette smoke, whereas only higher puff frequency led to lower levels of toxicants in Yellow HEETS aerosol. Some HEETS varieties exhibited higher levels of formaldehyde and TSNAs in their aerosols compared to Yellow HEETS. Puff frequency was identified as the only smoking parameter that significantly lowered the release of almost all toxicants in Yellow HEETS, whereas a combination of higher puff volume and puff duration led to increased levels of some carbonyls. Differences in toxicant levels between various commercially available HEETS have important implications when assessing their health impact, as their consumption might induce different toxicant exposure and health effects. HEETS release about half as much nicotine and substantially lower levels of toxicants compared to cigarettes. Literature data showed that puffing intensity is increased in cigarette smokers switching to HEETS, maybe in reaction to these lower nicotine levels. Our results show a differential impact of increased puff frequency, puff duration, and puff volume in the release of toxicants from HEETS. Thus, industry-independent studies on puff topography are critical to make choices for the most relevant puffing regime for heated tobacco product regulation. Regulators should consider evaluating the health impact of multiple HEETS varieties, as the tobacco filler composition significantly affects the release of certain toxicants.

Using a Novel Connected Device for the Collection of Puffing Topography Data for the Vuse Solo Electronic Nicotine Delivery System in a Real-World Setting: Prospective Ambulatory Clinical Study.

Over the last decade, the use of electronic nicotine delivery systems (ENDSs) has risen, whereas studies that describe how consumers use these products have been limited. Most studies related to ENDS use have involved study designs focused on use in a central location environment or attempted to measure use outcomes through subjective self-reported end points. The development of accurate and reliable tools to collect data in a naturalistic real-world environment is necessary to capture the complexities of ENDS use. Using connected devices in a real-world setting provides a convenient and objective approach to collecting behavioral outcomes with ENDS. The Product Use and Behavior instrument was developed and used to capture the use of the Vuse Solo ENDS in an ambulatory setting to best replicate real-world use behavior. This study aims to determine overall mean values for topography outcomes while also providing a definition for an ENDS use session. A prospective ambulatory clinical study was performed with the Product Use and Behavior instrument. Participants (n=75) were aged between 21 and 60 years, considered in good health, and were required to be established regular users of ENDSs. To better understand use behavior within the population, the sample was sorted into percentiles with bins based on daily puff counts. To frame these data in the relevant context, they were binned into low-, moderate-, and high-use categories (10th to 40th, 40th to 70th, and 70th to 100th percentiles, respectively), with the low-use group representing the nonintense category, the high-use group representing the intense category, and the moderate-use group being reflective of the average consumer. Participants with higher daily use took substantially more puffs per use session (6.71 vs 4.40) and puffed more frequently (interpuff interval: 32.78 s vs 61.66 s) than participants in the low-use group. Puff duration remained consistent across the low-, moderate‑, and high-use groups (2.10 s, 2.18 s, and 2.19 s, respectively). The moderate-use group had significantly shorter session lengths (P<.001) than the high- and low-use groups, which did not differ significantly from each other (P=.16). Using connected devices allows for a convenient and robust approach to the collection of behavioral outcomes related to product use in an ambulatory setting. By using the variables captured with these tools, it becomes possible to move away from predefined periods of use to better understand topography outcomes and define use sessions. The data presented here offer a possible method to define these sessions. These data also begin to frame international standards used for the analytical assessments of ENDSs in the correct context and begin to shed light on the differences between standardized testing regimens and actual use behavior. Clinicaltrials.gov NCT04226404; https://clinicaltrials.gov/study/NCT04226404.

Photometric Monitoring of Electronic Cigarette Puff Topography.

To study and monitor the adverse health consequences of using electronic cigarettes, a user's puff topography, which are quantification parameters of the user's vaping habits, plays a central role. In this work, we introduce a topography sensor to measure the mass of total particulate matter generated in every puff and to estimate the nicotine yield. The sensor is compact and low-cost, and is integrated into the electronic cigarette device to promptly and conveniently monitor the user's daily puff topography. The topography sensor is comprised of a photometric sensor and a pressure sensor. The photometric sensor measures the mass concentration of the aerosol, based on scattering of near-infrared light from airborne particles, while the pressure sensor measures the flow rate. The topography sensor was tested under various conditions including a wide range of atomizer power, puff duration, and inhalation pressure. The sensor's accuracy was validated by comparing the sensor's readings with reference measurements, and the results matched closely with the trends reported by existing studies on electronic cigarettes. An example application for tracking a user's puff topography was also demonstrated. Our topography sensor holds great promise in mitigating the health risks of vaping, and in promoting quality control of electronic cigarette products.

Bigger, stronger and cheaper: growth in e-cigarette market driven by disposable devices with more e-liquid, higher nicotine concentration and declining prices

ObjectiveGiven the evolving changes in the disposable e-cigarette market, we explore patterns of sales in the USA by e-liquid volume capacity, nicotine strength and real sales-weighted average prices by both...

DeepPuff: Utilizing Deep Learning for Smoking Behavior Identification in Free-living Environment.

A comprehensive assessment of cigarette smoking behavior and its effect on health requires a detailed examination of smoke exposure. We propose a CNN-LSTM-based deep learning architecture named DeepPuff to quantify Respiratory Smoke Exposure Metrics (RSEM). Smoke inhalations were detected from the breathing and hand gesture sensors of the Personal Automatic Cigarette Tracker v2 (PACT 2.0). The DeepPuff model for smoke inhalation detection was developed using data collected from 190 cigarette smoking events from 38 medium to heavy smokers and optimized for precision (avoidance of false positives). An independent dataset of 459 smoking events from 45 participants (90 smoking events in the lab and 369 smoking events in free-living conditions) was used for testing the model. The proposed model achieved a precision of 82.39% on the training and 93.80% on the testing dataset (95.88% in the lab and 93.78% in free-living). RSEM metrics were then computed from the breathing signal of each detected smoke inhalation. Results from the RSEM algorithm were compared with respiratory metrics obtained from video annotation. Smoke exposure metrics of puff duration, inhale-exhale duration, and inhalation duration were not statistically different from the ground truth generated through video annotation. The results suggest that DeepPuff may be used as a reliable means to measure respiratory smoke exposure metrics collected under free-living conditions.

Experimental investigation on the dynamic behavior and microscopic characteristics of the aerosol produced by ceramic coil atomizer of e-cigarettes

The ceramic coil atomizers of e-cigarettes heat and vaporize the e-liquid to produce an inhalable e-aerosol. In this study, we built an e-aerosols generation system to experimentally investigate the influences of the puff duration, heating power and puff pressure on the particle size distribution and the representative diameters within the e-aerosol. The e-aerosol generation process recorded by a high-speed camera shows that the periodic boiling on the surface of the atomizer involving bubble formation, growth, coalescence and breakup dominates the subsequent atomization and vaporization of the e-liquid, producing plenty of e-aerosols. The measurements using a particle size analyzer show that the e-aerosol size distribution reaches relatively stable since 3 s after the trigger of puff, where Sauter Mean Diameter keeps stable at around 0.42 μm, implying that the e-aerosol production enters the steady stage. Increasing the heating power from 4.5 to 6.5 W improves the atomization quality, as indicated by the homogenization and reduction of the particle size. However, further increasing heating power over 6.5 W helps little to the atomization quality. As the puff pressure increases from 0.5 to 1.5 kPa, the representative diameters of e-aerosol are insensitive to puff pressure, while further increasing puff pressure over 1.5 kPa causes a rapid increase of representative diameters, accompanied by a broader size spectrum and more large particles. Correlations have been proposed to describe the relationship between the representative diameters and heating power and puff pressure. Finally, The heating power of 6.5 W and puff pressure of 1.5 kPa are recommended as the optimal parameters for the practical use of e-cigarettes, since the throat hit could be greatly avoided and the atomization quality of e-liquid reaches the best level.

Sensory appeal and puffing intensity of e-cigarette use: Influence of nicotine salts versus free-base nicotine in e-liquids

BackgroundIn the US, nicotine salts (with protonated nicotine instead of free-based nicotine) have been reported to lower the harshness and bitterness of e-cigarette aerosols, making it easier to inhale high levels of nicotine. This study aimed to determine whether nicotine salts also increase sensory appeal at lower concentrations (< 20mg/mL). Moreover, and novel, inhalation intensity of both types of e-liquids was compared. MethodsIn a randomized, double-blinded, within-participants design, healthy adults who use e-cigarettes (n=68) vaped tobacco-flavored e-liquids containing 12mg/mL of free-based nicotine or nicotine salt ad libitum, using their own device, during two online sessions (June-July 2021, Utrecht, The Netherlands). The sensory parameters perceived liking, nicotine intensity, harshness, and pleasantness were rated on a 100-unit visual analog scale. The intensity of use was determined by the recorded puff number, duration and interval. ResultsTest scores on appeal, harshness and puffing behavior parameters showed no significant differences between the nicotine salt and the free-base condition. The average inhalation time was 2.5seconds. Additional analyses found no significant effect of liquid order, age, gender, smoking status, vaping frequency and familiarity with nicotine salts. Significant positive correlations were found between the sensory parameters except for harshness. ConclusionsContrary to a previous study that used higher nicotine concentrations and standardized puffing conditions in a laboratory setting, we did not observe the effects of nicotine salts on sensory appeal in our real-life study paradigm. Moreover, we did not see effects on study parameters related to puffing intensity.

Usage Pattern and Nicotine Delivery during Ad Libitum Consumption of Pod E-Cigarettes and Heated Tobacco Products.

Many different nicotine delivery products, such as e-cigarettes (e-cigs) or heated tobacco products (HTPs), are available on the market. To better understand these products, it is crucial to learn how consumers use them and how much nicotine they deliver. Therefore, a pod e-cig, an HTP, and a conventional cigarette (CC) were each used by 15 experienced users of the respective product category for 90 min without special use instructions ("ad libitum"). Sessions were video recorded to analyze usage patterns and puff topography. At defined time points, blood was sampled to determine nicotine concentrations, and subjective effects were inquired about using questionnaires. During the study period, the CC and HTP groups averaged the same number of consumption units (both 4.2 units). In the pod e-cig group, the highest number of puffs was taken (pod e-cig 71.9; HTP: 52.2; CC: 42.3 puffs) with the most extended mean puff duration (pod e-cig: 2.8 s; HTP: 1.9 s; CC: 1.8 s). Pod e-cigs were predominantly used with single puffs or in short clusters of 2-5 puffs. The maximum plasma nicotine concentration was highest for CCs, followed by HTPs, and then pod e-cigs with 24.0, 17.7, and 8.0 ng/mL, respectively. Craving was reduced by all products. The results suggest that the high nicotine delivery known for tobacco-containing products (CCs and HTPs) may not be needed for non-tobacco-containing products (pod e-cigs) to satisfy cravings in experienced users.