Mainstream Aerosol Research Articles

Formate Emission in the Mainstream Aerosols of Heated Tobacco Products Distributed in Japan

Formate Emission in the Mainstream Aerosols of Heated Tobacco Products Distributed in Japan

Opinion: Should high-resolution differential mobility analyzers be used in mainstream aerosol studies?

Abstract. Differential mobility analyzers (DMAs) are widely used instruments to measure the size distributions of submicron aerosols. High-resolution DMAs (HRDMAs) are defined here as plain DMAs maintaining a steady flow over an unusually broad range of sheath gas flow rates Q. HRDMAs, first developed by Georg Reischl's group, have existed for a long time. However, they have not been widely adopted, except in the size range below 10 nm, often in new particle formation studies. Here we question the commonly held view that HRDMAs are necessarily complex, bulky and expensive machines, mainly of interest in exotic applications outside mainstream aerosol research. Rather, many studies central to aerosol research could be carried out with HRDMAs with considerable advantage in size range, resolution, sensitivity and measurement speed. DMA manufacturers will hopefully take the challenge of developing commercial HRDMAs of complexity and cost comparable to those of today's commercial instruments, adapted for broad use by aerosol scientists, though with greatly improved flexibility and performance. Some of the technical challenges that still need to be overcome are discussed, such as the development of high-flow condensation counter detectors, and the control of high sample and sheath gas flow rates.

PM1 exposure and spatial transmission of nicotine from the simulated second-hand vapor of pod-based electronic cigarettes

Electronic cigarettes (E-cigarettes) have gained significant popularity in recent years as a substitute for combustible cigarettes. However, there is growing concern regarding the safety of E-cigarette products for both the users and those exposed passively to second-hand emissions, which contain nicotine and other toxic substances. In particular, the characteristics of second-hand PM1 exposure and the transmission of nicotine from E-cigarettes remain unclear. In this study, the untrapped mainstream aerosols from the E-cigarette and smoke from cigarettes were exhausted by the smoking machines which were operated under standardized puffing regimes to simulate second-hand vapor or smoke exposure. The concentrations and components of PM1 released from cigarettes and E-cigarettes were compared under varying environmental conditions and regulated using a heating, ventilation, and air conditioning (HVAC) system. Additionally, the ambient nicotine concentrations and the size distribution of the generated aerosols were determined at different distances from the release source. Results showed that PM1 accounted for the highest proportion (98 %) of the released particulate matter (PM1, PM2.5, and PM10). The mass median aerodynamic diameter (MMAD) of cigarette smoke (0.5 ± 0.01 μm, geometric standard deviation (GSD) 1.97 ± 0.1) was smaller than that of E-cigarette aerosols (1.06 ± 0.14 μm, GSD 1.79 ± 0.19). The PM1 concentrations and chemical components were effectively reduced when the HVAC system was utilized. Nicotine concentrations in E-cigarette aerosols were comparable to those of combustible cigarette emissions when close to the exposure source (0 m), while they declined more rapidly than cigarette smoke emissions with increasing distance from the source. Furthermore, the maximum nicotine concentrations occurred in 1 μm and 0.5 μm particles in E-cigarette and cigarette emissions, respectively. These results provide a scientific basis for the assessment of E-cigarette and cigarette aerosol passive exposure risks, guiding the development of environmental and human health control measures for these products.

Difference between global and regional aerosol model classifications and associated implications for spaceborne aerosol optical depth retrieval

AbstractAerosol model are generally adopted to describe the physical and optical characteristics of aerosols in different regions, and this is important for climate and environmental studies as well as satellite aerosol retrieval. However, current mainstream aerosol retrieval algorithms still lack differentiated and dynamic descriptions of aerosol models, and the aerosol optical depth (AOD) retrieval accuracy is hence largely compromised. Therefore, in this study, we aimed to investigate the difference between global and regional aerosol model classifications and the impact of these differences on satellite AOD retrieval. We developed global and regional (for China) aerosol models through the K-means cluster analysis method, and used the 6SV radiative transfer model based on these global and regional aerosol models to simulate air pollution events. The cluster analysis revealed that both global and regional aerosols can be clustered into five main aerosol types with different optical and physical parameters. The aerosol types include strongly absorbing, moderately absorbing, weakly absorbing, dust and coarse-fine mixed aerosols. These two aerosol models exhibited distinct seasonal variations. Comparing the clustering results obtained with the two models at five Aerosol Robotic Network (AERONET) sites, we found that the proportion of strongly absorbing aerosols in the global results is low. According to the China clustering results, a higher proportion of strongly absorbing aerosols occurred in autumn, winter, and early spring, and dust aerosols attained an increasing proportion in spring. Comparing the aerosol parameters with observational data, the regional aerosol model performed better than the global aerosol model. Simulations of AOD during a pollution episode and in different seasons at the Beijing-CAMS site with the 6SV radiative transfer model further confirmed that the regional aerosol model achieved a better simulation accuracy than the global model. The findings suggest that regional aerosol models can provide a useful reference for satellite remote sensing algorithm, climate change and air pollution assessment, and that the dynamic description of the aerosol model is a key parameter in satellite AOD retrieval algorithms.

Current Knowledge and Challenges of Particle Size Measurements of Mainstream E-Cigarette Aerosols and Their Implication on Respiratory Dosimetry

The E-cigarette has been promoted as an alternative nicotine delivery device with potentially fewer toxicant emissions. The objective of this review is to summarize the current knowledge on the particle size distribution (PSD) of e-cigarette emissions and to analyze the knowledge gaps between existing particle size measurements and the vision toward harm reduction from e-cigarette use. Here, we focus on firstly describing the physical parameters used to characterize PSD, followed by comparing particle size measurement approaches, investigating the factors that impact the PSD of e-cigarette mainstream aerosols, and conclude by linking size distribution to the respiratory dosimetry by demonstrating the modeling results of particle deposition in the respiratory tract. This review calls for a harmonized testing protocol to conduct inter-comparisons and further understand e-cigarette particle sizes. Among the influencing factors investigated, puff topography, operation power, flavorings, PG/VG ratio, and nicotine strength impose a substantial impact on the PSD, but the underlying mechanisms have not yet been fully investigated. The effects brought by the type of device refill and nicotine are yet inconclusive due to lack of evidence. Coil aging has no significant impact on the PSD of e-cigarette aerosols within the coil lifetime. Lastly, while computational models of particle deposition have been adopted to profile the deposition of e-cigarette mainstream emissions, existing models have limited applicability and generality when dealing with e-cigarette aerosols that have high volatility and hygroscopicity, which can dynamically evaporate or grow during the transport process. Additionally, the size-dependent chemical composition (e.g., nicotine and harmful and potentially harmful constituents) of e-cigarette aerosols is unknown, impeding the understanding of the health effects of e-cigarette use. Therefore, it is essential for future studies to bridge these knowledge gaps and unveil the mechanisms determining PSD and respiratory deposition.

Aerosol Formation and Transfer in Open- and Closed-Ended Heated Tobacco Products

Summary A lit cigarette forms a positive and negative pressure zone by a puff with respect to the position of its paper burn line. Smoke aerosols generated from the two zones are then pulled through the rod under the puff to form the mainstream smoke. This phenomenon is fundamental to the thermophysics and the resultant chemical composition of the mainstream smoke. In this study, we created two different airflow pathways inside a heated tobacco rod by a puff, and investigated the differences in aerosol formation and its chemical compositions. The two different pressure-induced conditions, one through an open-ended tobacco rod (marked as HNB, a label of a designed airflow pathway of commercial heated tobacco products called heat-not-burn prior), and the other through a closed-ended tobacco rod (marked as NSC, a label of a novel-designed airflow pathway of heated tobacco products), were compared for their aerosol collected mass (ACM), the contents of nicotine, water and added aerosol agents such as propylene glycol (PG) and glycerol (VG), as well as selected aldehydes and ketones in the mainstream aerosol. Aerosol particle distribution and the heated temperature along different rod locations were also compared during a puff. The results indicated marked differences in the aerosol formation processes between the two HNB and NSC systems. The transfer ratios of the main aerosol components were significantly higher for the NSC; the levels of formaldehyde and acetaldehyde were significantly lower under the NSC than the HNB condition. There were also significant differences for the aerosol particle number concentration (APNC) and count median diameter (CMD) for the two systems. The lack of convective heat transfer in the aerosol formation under the NSC condition resulted in a relatively stable thermal aerosol generation zone, reflected by the temperature difference between the two systems in the selected locations. The NSC mode of tobacco heating thus offers a novel and enhanced aerosol generation for heat tobacco product designs.

Effect of Heating Temperature on Ammonia Emission in the Mainstream Aerosols from Heated Tobacco Products.

Heated tobacco products are devices that deliver nicotine into the body via inhalation of the mainstream aerosols generated during direct and/or indirect heating of tobacco leaf material. Ammonia in aerosols potentially increases the alkalinity and, therefore, the proportion of free nicotine for easy absorption. Meanwhile, ammonia can be a cause of adverse health effects when involved in the aerosols. This study aimed to grasp the emission behaviour of ammonia in the mainstream aerosols generated from four kinds of devices that employ different heating temperatures from 40 to 350 °C. The aerosols were generated by a vaping machine following the CRM 81 puffing protocol. Ammonia in the forms of gas and particles was trapped in 5 mM oxalic acid and subsequently determined by ion chromatography. The results showed that the total emission amount of ammonia increased with an increase in the heating temperature regardless of the device used. The gas-particle distribution of ammonia also depended on the heating temperature; gaseous ammonia was only found in the device with 40 °C of the heating temperature. These results show that ammonia in the mainstream aerosols was emitted from a common thermal process, probably thermal extraction in water vapour from a tobacco leaf.

Impact of e-Liquid Composition, Coil Temperature, and Puff Topography on the Aerosol Chemistry of Electronic Cigarettes

E-cigarette aerosol is a complex mixture of gases and particles with a composition that is dependent on the e-liquid formulation, puffing regimen, and device operational parameters. This work investigated mainstream aerosols from a third generation device, as a function of coil temperature (315-510 °F, or 157-266 °C), puff duration (2-4 s), and the ratio of propylene glycol (PG) to vegetable glycerin (VG) in e-liquid (100:0-0:100). Targeted and untargeted analyses using liquid chromatography high-resolution mass spectrometry, gas chromatography, in situ chemical ionization mass spectrometry, and gravimetry were used for chemical characterizations. PG and VG were found to be the major constituents (>99%) in both phases of the aerosol. Most e-cigarette components were observed to be volatile or semivolatile under the conditions tested. PG was found almost entirely in the gas phase, while VG had a sizable particle component. Nicotine was only observed in the particle phase. The production of aerosol mass and carbonyl degradation products dramatically increased with higher coil temperature and puff duration, but decreased with increasing VG fraction in the e-liquid. An exception is acrolein, which increased with increasing VG. The formation of carbonyls was dominated by the heat-induced dehydration mechanism in the temperature range studied, yet radical reactions also played an important role. The findings from this study identified open questions regarding both pathways. The vaping process consumed PG significantly faster than VG under all tested conditions, suggesting that e-liquids become more enriched in VG and the exposure to acrolein significantly increases as vaping continues. It can be estimated that a 30:70 initial ratio of PG:VG in the e-liquid becomes almost entirely VG when 60-70% of e-liquid remains during the vaping process at 375 °F (191 °C). This work underscores the need for further research on the puffing lifecycle of e-cigarettes.

A 6-month inhalation toxicology study in Apoe\u2212/\u2212 mice demonstrates substantially lower effects of e-vapor aerosol compared with cigarette smoke in the respiratory tract

Cigarette smoking is the major cause of chronic obstructive pulmonary disease. Considerable attention has been paid to the reduced harm potential of nicotine-containing inhalable products such as electronic cigarettes (e-cigarettes). We investigated the effects of mainstream cigarette smoke (CS) and e-vapor aerosols (containing nicotine and flavor) generated by a capillary aerosol generator on emphysematous changes, lung function, and molecular alterations in the respiratory system of female Apoe−/− mice. Mice were exposed daily (3 h/day, 5 days/week) for 6 months to aerosols from three different e-vapor formulations—(1) carrier (propylene glycol and vegetable glycerol), (2) base (carrier and nicotine), or (3) test (base and flavor)—or to CS from 3R4F reference cigarettes. The CS and base/test aerosol concentrations were matched at 35 µg nicotine/L. CS exposure, but not e-vapor exposure, led to impairment of lung function (pressure–volume loop area, A and K parameters, quasi-static elastance and compliance) and caused marked lung inflammation and emphysematous changes, which were confirmed histopathologically and morphometrically. CS exposure caused lung transcriptome (activation of oxidative stress and inflammatory responses), lipidome, and proteome dysregulation and changes in DNA methylation; in contrast, these effects were substantially reduced in response to the e-vapor aerosol exposure. Compared with sham, aerosol exposure (carrier, base, and test) caused a slight impact on lung inflammation and epithelia irritation. Our results demonstrated that, in comparison with CS, e-vapor aerosols induced substantially lower biological and pathological changes in the respiratory tract associated with chronic inflammation and emphysema.

Physical and chemical property of mainstream aerosol generated from heated tobacco products

Physical and chemical property of mainstream aerosol generated from heated tobacco products

Analysis of Nicotine and Non-nicotine Tobacco Constituents in Aqueous Smoke/Aerosol Extracts by UHPLC and Ultraperformance Convergence Chromatography-Tandem Mass Spectrometry.

The non-nicotine constituents of tobacco may alter the reinforcing effects of nicotine, but the quantitative and qualitative profiles of these chemicals in tobacco products such as electronic cigarettes (e-cigarettes), cigars, and waterpipe tobacco are not well characterized. The objective of this work was to develop and validate analytical methods to utilize saline both as an extraction solvent for smoke condensates from cigarettes, little cigars, and waterpipe tobacco and aerosols from e-cigarettes and as a delivery vehicle of nicotine and non-nicotine constitents for nonclinical pharmacological studies. Ultrahigh-performance liquid chromatography was used to analyze nicotine and acetaldehyde, and a novel ultraperformance convergence chromatography-tandem mass spectrometry method was developed to analyze anabasine, anatabine, cotinine, myosmine, nornicotine, harmane, and norharmane. Linearity was confirmed for each standard curve with correlation coefficients (r) ≥ 0.99, and relative errors (RE) for the standards were ≤±10% over the calibration ranges. Method validation was performed by preparing triplicate samples in saline to mimic the composition and concentration of each analyte in the smoke or aerosol condensate and were used to determine method accuracy and precision. Relative standard deviation values were ≤15% and mean RE ≤15% for each analyte at each concentration level. Selectivity of the methods was demonstrated by the absence of peaks in blank vehicle or diluent samples. Storage stability was assessed over ∼45 days. Precision (%RSD ≤ 13) and recovery (percent of day 0 ≥ 80%) indicated that the saline formulations of all four products could be considered stable for up to ∼45 days at 4-8 °C. Therefore, the use of saline both as an extraction solvent and as a delivery vehicle adds versatility and improved performance in the study of the pharmacological effects of constituents from mainstream smoke and aerosols generated from cigarettes, little cigars, waterpipes, and e-cigarettes.

Chemosensory aerosol assessment of key attributes for tobacco products

AbstractHuman sensory evaluation plays an important role in assessing quality and supports commercial product development in many industries. However, sensory evaluation of tobacco products often requires highly trained specialists, is thus expensive, time‐consuming with low throughput capacity. To overcome such limitations, analytical platforms based on chemical fingerprints were proposed and evaluated in this work based on two different tobacco matrices. Using cigarette smoke as an example, the method was capable of predicting sensory attributes through chemical fingerprinting key tobacco and cigarette mainstream aerosol compositions. To achieve this, tobacco samples (comprising flue‐cured Virginia and air‐cured Burley types) and cigarette mainstream smoke samples were evaluated using high‐resolution mass spectrometry. The chemical fingerprint of each sample matrix was related to its respective reference sensory attributes, validated by highly trained panellists, to create predictive models based on partial least squares algorithm. These methodologies were further validated through a blind test with suitable prediction of all sensory attributes for single grade tobacco leaf and commercial blended cigarette smoke. The proposed methodology demonstrated satisfactory accuracy, repeatability and robustness, with prediction errors less than 20% for single grade tobaccos, and less than 11% for commercial products. When compared with human sensory evaluation, it significantly improved analytical capacity (over 100 samples per day) at comparable or improved accuracy. This method could be applied to evaluate other novel tobacco products such as heated tobacco products.

An experimental aerosol air–agar interface mouse lymphoma assay methodology

This work investigates a completely novel and experimental concept of exposing L5178Y cells at the air-agar-interface to mainstream cigarette smoke aerosol (Kentucky reference 3R4F). This study highlights the associated challenges of combining a suspension cell line alongside an in vitro aerosol exposure system. To achieve a monolayer, cells were ‘seeded’ in a concentrated cell super-mix suspension onto an RPMI/agar-matrix -base. The resulting cell suspension media was adsorbed into the agar base leaving the L5178Y cells lightly suspended on the agar surface, approximating a monolayer. Cells were deemed supportable on the agar-matrix, viable and recoverable. Using Vitrocell VC 10 exposure system and the Ames 4 exposure module, L5178Y cells were successfully exposed to a dynamic cigarette smoke aerosol, recovered and assessed for mutant frequencies, using standard assay procedures. Method development included assessment of flowing air conditions, plating efficiency and recovery of L5178Y cells from the agar-matrix surface. Positive controls MMS and B[a]P were successfully incorporated into the agar-matrix and metabolic activation was achieved by S-9 incorporation into the same agar-base-matrix. B[a]P demonstrated metabolic activation and positive response, suggesting a clear cellular interaction with the agar-matrix. Whole smoke exposed cells in the presence of metabolic activation showed a clear dose response and increasing mutant frequencies, well in excess of the controls (air and incubator) and the global evaluation factor following a 2 or 3 day expression period. This experimental concept demonstrates that L5178Y cells can be exposed to cigarette smoke aerosol, using a completely novel and a previously untested approach. Although this work successfully demonstrates the approach is viable and cells can be plated and maintained on an agar-matrix, more optimisation and robustness assessment is required before it can be considered fully adapted and used alongside other whole aerosol methodologies for the assessment of cigarette smoke and other inhaled aerosols.

Comprehensive chemical characterization of the aerosol generated by a heated tobacco product by untargeted screening

A suite of untargeted methods has been applied for the characterization of aerosol from the Tobacco Heating System 2.2 (THS2.2), a heated tobacco product developed by Philip Morris Products S.A. and commercialized under the brand name IQOS®. A total of 529 chemical constituents, excluding water, glycerin, and nicotine, were present in the mainstream aerosol of THS2.2, generated by following the Health Canada intense smoking regimen, at concentrations ≥ 100 ng/item. The majority were present in the particulate phase (n = 402), representing more than 80% of the total mass determined by untargeted screening; a proportion were present in both particulate and gas-vapor phases (39 compounds). The identities for 80% of all chemical constituents (representing > 96% of the total determined mass) were confirmed by the use of authentic analytical reference materials. Despite the uncertainties that are recognized to be associated with aerosol-based untargeted approaches, the reported data remain indicative that the uncharacterized fraction of TPM generated by THS2.2 has been evaluated to the fullest practicable extent. To the best of our knowledge, this work represents the most comprehensive chemical characterization of a heated tobacco aerosol to date.Graphical abstract

Effects of Electronic Cigarettes on Indoor Air Quality and Health

With the rapid increase in electronic cigarette (e-cig) users worldwide, secondhand exposure to e-cig aerosols has become a serious public health concern. We summarize the evidence on the effects of e-cigs on indoor air quality, chemical compositions of mainstream and secondhand e-cig aerosols, and associated respiratory and cardiovascular effects. The use of e-cigs in indoor environments leads to high levels of fine and ultrafine particles similar to tobacco cigarettes (t-cigs). Concentrations of chemical compounds in e-cig aerosols are generally lower than those in t-cig smoke, but a substantial amount of vaporized propylene glycol, vegetable glycerin, nicotine, and toxic substances, such as aldehydes and heavy metals, has been reported. Exposures to mainstream e-cig aerosols have biologic effects but only limited evidence shows adverse respiratory and cardiovascular effects in humans. Long-term studies are needed to better understand the dosimetry and health effects of exposures to secondhand e-cig aerosols.

Characterization of mainstream cigarette smoke aerosol by size-fractionated chemical analysis of nicotine, solanesol, and tobacco-specific nitrosamines

The distribution of key chemicals in mainstream cigarette smoke (MCS) particles of different sizes have implications for respiratory dose. In this study, a differential mobility spectrometer (DMS) and an electrical low-pressure impactor (ELPI) were used to characterize MCS particles generated from three cigarettes (3R4F, Dunhill, and Hongtashan). In addition, the ELPI was used to collect smoke particles of three different aerodynamic diameters (144, 431, and 722 nm) from 3R4F MCS, which were analyzed for nicotine, solanesol and tobacco-specific nitrosamines (TSNAs). The number concentration, particle size distribution, and count median diameter (CMD) of the MCS particles characterized by DMS and ELPI were compared quantitatively. The observed difference in the physical characterization results of MCS particles may be due to a myriad of discrepancies between the two techniques. Chemical analyses of the three ELPI selected particle sizes showed that, after normalization to total particulate matter (TPM), nicotine and TSNAs were distributed evenly, whereas solanesol showed a tendency to increase with increasing particle diameter. Notably, the distribution of nicotine and four TSNAs was independent of the three particle sizes; however, the amount of solanesol showed a slight dependency on particle size, varying by less than 23.4% over the size range considered.

IQOS: examination of Philip Morris International’s claim of reduced exposure

BackgroundNew electronic heated tobacco products are being introduced in the global market and are gaining popularity. In 2016, Philip Morris International, Inc. (PMI) submitted a modified risk tobacco product (MRTP)...

Possible hepatotoxicity of IQOS

On 25 January 2018, the Food and Drug Administration (FDA) Tobacco Scientific Advisory Committee unanimously voted (with one abstention) that Phillip Morris International (PMI) could not claim their heated tobacco...

Second-hand aerosol from tobacco and electronic cigarettes: Evaluation of the smoker emission rates and doses and lung cancer risk of passive smokers and vapers

Smoking activities still represent the main, and preventable, cause of lung cancer risk worldwide. For this reason, a number of studies were carried out to deepen and better characterize the emission of cigarette-generated mainstream aerosols in order to perform an a-priori evaluation of the particle doses and related lung cancer risks received by active smokers. On the contrary, a gap of knowledge still exists in evaluating the dose and risk received by passive smokers in indoor private micro-environments (e.g. homes). For this purpose, in the present paper, an experimental campaign was performed to evaluate the exposure to second-hand aerosol from conventional and electronic cigarettes and to estimate the consequent dose received by passive smokers/vapers and the related lung cancer risk.Measurements of exposure levels in terms of particle number, PM10 and black carbon concentrations, as well as particle size distributions, were performed in a naturally ventilated indoor environment during smoking activities of tobacco and electronic cigarettes. The particle emission rates of smokers and vapers, for the different aerosol metrics under investigation, were evaluated. Moreover, for a typical exposure scenario, the dose received by the passive smokers/vapers in a naturally ventilated indoor micro-environment was estimated through a Multiple-Path Particle Dosimetry (MPPD) model able to assess the particle dose received in the different tracts of the respiratory systems. Furthermore, on the basis of scientific literature data about mass fraction of carcinogenic compounds contained in cigarette-emitted particles (i.e. Heavy Metals, Benzo-a-pyrene and nitrosamines) and the estimated doses, the excess life cancer risk (ELCR) for passive smokers/vapers was evaluated. Cumulative respiratory doses for passive smokers were up to 15-fold higher than for passive vapers. The ELCR for second-hand smokers was five orders of magnitude larger than for second-hand vapers.

Characterization of airborne particles emitted by an electrically heated tobacco smoking system

Smoking activities were recognized as a main risk factor for population. Indeed, mainstream smoke aerosol is directly inhaled by smokers then delivering harmful compounds in the deepest regions of the lung. In order to reduce the potential risk of smoking, different nicotine delivery products have been recently developed. The latest device released is an electrically heated tobacco system (iQOS®, Philip Morris) which is able to warm the tobacco with no combustion. In the present paper a dimensional and volatility characterization of iQOS-generated particles was performed through particle number concentration and distribution measurements in the mainstream aerosol. The experimental analysis was carried out through a condensation particle counter, a fast mobility particle sizer and a thermo-dilution sampling system allowing aerosol samplings at different temperatures. Estimates of the particle surface area dose received by smokers were also carried out on the basis of measured data and typical smoking patterns.The particle number concentrations in the mainstream aerosols resulted lower than 1 × 108 part. cm−3 with particle number distribution modes of about 100 nm. Nonetheless, the volatility analysis showed the high amount of volatile fraction of iQOS-generated particles, indeed, samplings performed at 300 °C confirmed a significant particle shrinking phenomena (modes of about 20 nm). Anyway, the particle number concentration does not statistically decrease at higher sampling temperatures, then showing that a non-volatile fraction is always presents in the emitted particles. The dose received by smokers in terms of non-volatile amount of particle surface area was equal to 1–2 mm2 per puff, i.e. up to 4-fold larger than that received by electronic cigarette vapers.