In recent years, the use of electronic vaping products (also named e-cigarettes) has increased due to their appealing flavors and nicotine delivery without the combustion of tobacco. Although the hazardous substances emitted by e-cigarettes are largely found to be much lower than combustible cigarettes, second-hand exposure to e-cigarette aerosols is not completely benign for bystanders. This work reviewed and synthesized findings on the second-hand exposure of aerosols from e-cigarettes and compared the results with those of the combustible cigarettes. In this review, different results were integrated based upon sampling locations such as residences, vehicles, offices, public places, and experimental exposure chambers. In addition, the factors that influence the second-hand exposure levels were identified by objectively reviewing and integrating the impacts of combustible cigarettes and e-cigarettes on the environment. It is a challenge to compare the literature data directly to assess the effect of smoking/vaping on the indoor environment. The room volume, indoor air exchange rate, puffing duration, and puffing numbers should be considered, which are important factors in determining the degree of pollution. Therefore, it is necessary to calculate the \"emission rate\" to normalize the concentration of pollutants emitted under various experimental conditions and make the results comparable. This review aims to increase the awareness regarding the harmful effects of the second-hand exposure to aerosols coming from the use of cigarettes and e-cigarettes, identify knowledge gaps, and provide a scientific basis for future policy interventions with regard to the regulation of smoking and vaping.

BACKGROUND: The purpose of this study is to examine the use of electronic cigarettes (e-cigarettes) among college students in Hangzhou, and to analyze the influencing factors of their intention to use e-cigarettes.
METHODS: Using a stratified cluster sampling method, 775 students from two universities in Hangzhou were selected for an on-site questionnaire survey from March to April 2022. Adjusted logistic regression analysis was conducted on the influencing factors of use intention, based on innovation diffusion theory.
RESULTS: Within our sample of college students, 16.5% of students had tried e-cigarettes; 6.32% had used e-cigarettes in the past month, and 8.0% had the intention to use e-cigarettes. There were significant differences in willingness to use e-cigarettes among different genders, economic status, smoking status of close friends around them, and their own use of tobacco and alcohol (p<0.05). The logistic regression model showed that the observability of e-cigarettes (AOR=1.28; p<0.05), personal factors (AOR=1.39; p<0.05), and social systems (AOR=1.63; p<0.05), were all influencing factors of intention to use e-cigarettes.
CONCLUSIONS: College students in Hangzhou have a high intention to use e-cigarettes, and the impacts of the product itself, individual characteristics and the living environment are crucial. It is necessary to strengthen the promotion of tobacco knowledge at the social and family levels to reduce the occurrence of vaping.

The prevalence of dual usage and the relatively low cessation rate among e-cigarette (EC) users suggest that ECs have not demonstrated significant effectiveness as a smoking cessation tool. Furthermore, there has been a substantial increase in the prevalence of EC usage in recent years. Therefore, the objective of this study is to investigate the association between EC use and the incidence of respiratory symptoms and chronic obstructive pulmonary disease (COPD). A total of 10,326 participants aged between 20 and 55 years, without any respiratory diseases or COPD, were recruited for the study. These individuals attended employee physical examinations conducted at 16 public hospitals in Hebei province, China from 2015 to 2020. Logistic regression models were utilized to assess the association between EC use and the risk of respiratory symptoms and COPD using risk ratios along with their corresponding 95% confidence intervals. Restricted cubic spline functions were employed to investigate the dose-response non-linear relationship. The robustness of the logistic regression models was evaluated through subgroup analyses, and sensitivity analyses. During the 5-year follow-up period, a total of 1071 incident cases of respiratory symptoms and 146 incident cases of COPD were identified in this cohort study. After adjusting for relevant confounding factors, EC users demonstrated a respective increase in the risk of reporting respiratory symptoms and COPD by 28% and 8%. Furthermore, dual users who used both ECs and combustible cigarettes exhibited an elevated risk of incident respiratory symptoms and COPD by 41% and 18%, respectively, compared to those who had never used non-users of any cigarette products. The association between daily EC consumption and the development of respiratory symptoms, as well as COPD, demonstrated a significant J-shaped pattern. The potential adverse association between the consumption of ECs, particularly when used in combination with combustible cigarettes, and the development of respiratory symptoms and COPD necessitates careful consideration. Policymakers should approach ECs cautiously as a prospective smoking cessation tool.

MDMB-4F-BICA, also known as 4F-MDMB-BICA, is a new psychoactive substance that emerged in 2020. It is often illegally added to electronic cigarette oil for inhalation abuse, leading to serious adverse symptoms and even death. There are significant differences in pharmacokinetics between inhalation administration and conventional drug delivery methods. Inhalation administration can pass through the blood-brain barrier to enter the brain directly. However, the specific distribution of the drug in the brain following inhalation has not been well investigated. In order to scientifically compare the absorption and distribution of MDMB-4F-BICA after two administration methods (inhalation and subcutaneous injection), this study analyzed the drug concentration in mice blood and brain by LC-MS/MS after systemic exposure inhalation in the form of electronic cigarettes. The aim was to conduct the pharmacokinetics study of MDMB-4F-BICA after inhalation(\'vapor\') administration. Pharmacokinetics and distribution of the compound revealed that the maximum concentrations in blood of this compound were reached at 0.5 min and 15 min, respectively, and the concentration in the brain reached the maximum at the same time after two modes of administration. The drug concentration in the brain was higher than that of subcutaneous injection, and the drug remained at a low concentration in the brain for a long period (20 ng/g brain tissue) with a significant distribution in several olfactory primary cortex brain regions. Taken together, the pharmacokinetics of the synthetic cannabinoid MDMB-4F-BICA after single systemic exposure inhalation were investigated for the first time in this study. A basis for subsequent evaluation research of inhalation-related harmfulness is provided by comparing the distribution of drugs in the brain after the two administration modes.

There is an ongoing debate about whether e-cigarettes act as a gateway to tobacco smoking or contribute to smoking cessation, and relevant studies are limited among Chinese adolescents. This cross-sectional study therefore aimed to explore the relationship between e-cigarette use and susceptibility to tobacco product use among Chinese high school students.
The study population comprised 107,633 never smokers and 19,377 former smokers, generated from the 2019 China National Youth Tobacco Survey. The primary independent variables of interest were ever e-cigarette use, current e-cigarette use, and the frequency of current e-cigarette use. The main outcome was the susceptibility to tobacco product use. Multilevel logistic regression was used to estimate the association between the primary independent variables of interest and the outcome variable. Moreover, two additional multilevel logistic regression models were fitted using two alternative definitions of the outcome as the sensitivity analyses.
Among never smokers, students who ever used e-cigarettes were more likely to be susceptible to tobacco product use compared to students who never used e-cigarettes (AOR = 2.83, 95%CI = 2.59-3.08). Students who currently used e-cigarettes were more likely to be susceptible to tobacco product use than those who did not currently use e-cigarettes (AOR = 3.89, 95%CI = 3.21-4.72). Among former smokers, with the same settings of modeling, the AORs were 1.76 (95%CI = 1.62-1.91) and 3.16 (95%CI = 2.52-3.97), respectively. Similar results were obtained from the two sensitivity analyses.
Among Chinese high school students, both never smokers and former smokers, e-cigarette use, especially current e-cigarette use, was positively associated with susceptibility to tobacco product use. It is recommended to strengthen the monitoring of e-cigarettes and to provide targeted health education to adolescents.

Electronic cigarette (e-cigarette) usage has risen dramatically worldwide in recent years. It has been publicized as a safer alternative to the conventional combustible cigarette. This, however, has not yet been supported by robust toxicological research evidence. Analysis of the chemical compositions of e-liquids and generated aerosols is an important step in evaluating the toxicity effects of e-cigarettes. Currently, a broad spectrum of analytical methods have been employed for qualitative and quantitative analysis of chemical compositions of e-cigarette liquids and aerosols. The aim of this article is to review the advances in the chromatographic characterization of chemical composition of the latter in the recent five years. In addition, sample preparation methods for e-liquids and aerosols are surveyed and discussed. A study of the relevant literature indicates that, expectedly, gas chromatography and liquid chromatography with a variety of detection systems, particularly mass spectrometry, have been the main analytical techniques used in this field. Sample preparation procedures primarily include headspace sampling, dilute-and-shoot approach, liquid-liquid extraction and sorbent-based extraction for e-liquids and for aerosols (the latter usually with laboratory-built collection devices). Some challenges of current e-cigarette analytical research, and an overview on prospective work are also presented.

Electronic cigarettes have become increasingly popular, but the results of previous studies on electronic cigarette exposure in animals have been equivocal. This study aimed to evaluate the effects of electronic cigarette smoke (ECS) and cigarette smoke (CS) on lung function and pulmonary inflammation in mice to investigate whether electronic cigarettes are safer when compared to cigarettes. 32 specific pathogen-free BALB/c male mice were randomly grouped and exposed to fresh air (control), mint-flavored ECS (ECS1, 6 mg/kg), cheese-flavored ECS (ECS2, 6 mg/kg), and CS (6 mg/kg). After 3 weeks exposure to ECS or CS, we measured lung function (PIF and Penh) and blood oxygen saturation. The levels of TNF-α and IL-6 in the bronchoalveolar lavage fluid (BALF) and serum were measured using ELISA. HE staining was performed to observe the pathological changes in the lung tissues. The levels of IL-6 in BALF and serum, and TNF-α in BALF, were elevated similarly in the ECS and CS groups compared to the control group. Significant elevation was observed in serum TNF-α levels in the CS group. The total count of cells in BALF were increased after ECS1 exposure and CS exposure. PIF and oxygen saturation decreased, and Penh increased markedly in the CS group but not in the ECS groups. Compared with the ECS groups, mice in the CS group had widened lung tissue septa and increased inflammatory cell infiltration. However, we did not detect significant differences between mint-flavored and cheese-flavored e-cigarettes in our study. Overall, our findings suggested that both ECS and CS impair lung function and histopathology while promoting inflammation. In contrast, ECS has a less negative impact than CS.

BACKGROUND: This study was conducted to explore the characteristics and risk factors of e-cigarette use in adolescents, aiming for tobacco control and reducing e-cigarette use in this population.
METHODS: Using 1:1 matching, 88 students from three vocational high schools in Shanghai were recruited to conduct a case (using e-cigarettes) - control (not using e-cigarettes) study. Group interviews and questionnaire surveys were used for this qualitative and quantitative mixed-methods study. The keywords were extracted from the interview data and analyzed by the Colaizzi seven-step method.
RESULTS: The characteristics of adolescents\' use of e-cigarettes include young age at first use, consumption of a large amount, as well as smoking in discrete locations in order to hide from adults. The reasons for using e-cigarettes include curiosity and wanting to replace traditional cigarettes. The risk factors of using e-cigarettes include insufficient understanding of the harm of e-cigarettes at the individual level (The positive outcome expectancy points: Z= -3.746, p<0.001; The negative outcome expectancy points: Z= -3.882, p<0.001), peer influence at the interpersonal level (χ2=6.510, p<0.01), and the influence of social and environmental factors such as e-cigarette sales in the stores and WeChat Moments (p<0.05 for all associations).
CONCLUSIONS: Having friends who use e-cigarettes, curiosity and sales exposure about e-cigarettes are important factors affecting the use of e-cigarettes by adolescents. It is necessary to strengthen the publicity of the potential hazards of e-cigarettes and to reduce overall usage by improving relevant laws and regulations.

This study aims to analyze the association between combustible/electronic cigarettes and the risk of stroke.
We obtained data from the 2017-2018 National Health and Nutrition Examination Survey (NHANES). The stroke history and combustible/electronic cigarette use were acquired by questionnaires. Considering the sole or dual use of combustible cigarettes and electronic cigarettes (e-cigarettes), we divided all the individuals into four subgroups, including nonsmokers (reference group), sole combustible cigarette, sole e-cigarette, and dual use of both combustible cigarettes and e-cigarettes. We performed multivariable logistic regression to determine the association between cigarette use with the prevalence of stroke. We used odds ratios (ORs) with 95% confidence intervals (CIs) to show the effect size. Finally, we developed a prediction model to evaluate the risk of stroke for individuals with combustible or electronic cigarette use based on a random forest model.
We included a total of 4022 participants in the study. The median age was 55, and 48.3% of the participants were males. When we adjusted for age, gender, education attainment, race, total-to-HDL cholesterol (< 5.9 or ≥ 5.9), diabetes, hypertension, and alcohol consumption, the groups of sole e-cigarette use, sole combustible cigarette use, and dual use of combustible and electronic cigarettes were significantly associated with the prevalence of stroke with ORs (with 95%CI) of 2.07 (1.04-3.81), 2.36 (1.52-3.59), 2.34 (1.44-3.68), respectively. In the testing set, the AUC was 0.74 (95%CI = 0.65-0.84), sensitivity was 0.68, and specificity was 0.75.
Sole e-cigarettes and dual use of e-cigarettes with combustible cigarettes might increase the risk of stroke.

The prevalence of e-cigar among adolescents and young adults around the world is increasing rapidly, which has a serious impact on the health of young people. This study assessed the prevalence of e-cigar among college students and to explore the relationship between e-cigar use and personality traits.
This study conducted an electronic questionnaire survey on college students who were from three undergraduate universities and three junior colleges in Guangdong Province from January 2022 to March 2022. The survey was conducted by stratified cluster sampling, and the respondents were 1362. Statistical descriptions are used to describe the demographic characteristics and personality traits of participants. Mann-Whitney U tests, and Chi-square tests were used to compare the differences between current e-cigar users and non e-cigar users. Two-step hierarchical Logistic regression was used to predict the associated factors with e-cigar use.
The prevalence of current e-cigar users was 5.1%. Agreeableness showed statistically significant higher in non-users (Z = 2.585, P < 0.01). Moreover, gender (AOR = 0.312, 95%CI: 0.174-0.562), the relationship with mother (AOR = 5.887, 95%CI: 1.460-23.748), friends who use e-cigar (AOR = 3.808, 95%CI: 2.159-6.719), allowance per month (AOR = 2.482, 95%CI: 1.371-4.490), and agreeableness (AOR = 0.957, 95%CI: 0.918-0.997) were related to the use of e-cigar.
The level of agreeableness is associated with the use of e-cigar among college students. All these provided an important theoretical basis for future intervention.