Smoking Prevention Research Articles

Development of the UNC Perceived Message Effectiveness Scale for Youth

PurposeTobacco prevention media campaigns are an important tool to address youth tobacco use. We developed a theory-based perceived message effectiveness (PME) Scale to use when vetting messages for campaigns.MethodsParticipants were...

Family Support as Smoking Prevention during Transition from Early to Late Adolescence: A Study in 42 Countries.

Family support has a beneficial impact on protecting health-risk behaviour in adolescents. This study aimed to explore whether family support is associated with risk of smoking during transition from early (11 years) to late (15 years) adolescence across 42 countries. The data from the cross-national Health Behaviour in School-aged Children (HBSC) study in 2017/2018 were employed (N = 195,966). Family support was measured using the four-item Family dimension of the Multidimensional Scale of Perceived Social Support (sum score 20 or more was categorised as high family support). Smoking was defined as a reported cigarette smoking at least 1–2 days in the last 30 days. The association between smoking and family support was assessed using a prevalence ratio (PR) obtained from the multivariate Poisson regression. Over two thirds of adolescents reported high levels of support from their family. Family support was found to significantly decrease with age in most of the countries, with the boys reported high level of family support more often than girls. The adolescents who reported having low family support also were more likely to smoke compared to their peers who reported having high family support (PR = 1.81; 95% CI: 1.71–1.91 in boys, and PR = 2.19; 95% CI: 2.08–2.31 in girls). The countries with a stronger effect of family support in reducing smoking risk indicated lower rates of adolescent smoking as well as lower increases in the cigarette smoking prevalence during the age period from 11 to 15 years. This study reinforces the need for family support, which is an important asset helping adolescents to overcome the risk of smoking during their transition from early to late adolescence.

Smoking prevention in adolescents: a cross-sectional and qualitative evaluation of a newly implemented prevention program in Switzerland

ObjectivesIn 2014, a hospital-based smoking prevention programme ‘Nichtrauchen ist clever!’ (NIC!) for adolescents aged 12–14 was initiated. The aim of the study was to evaluate participants’ smoking behaviour and to...

Motivational Factors for Smoking Behaviors in Individuals with Metabolic Syndrome.

PurposeSmoking, which is one of the major risk factors for metabolic syndrome that causes cardiovascular disease or diabetes, is a crucial risk factor, which is modifiable. This study aimed to determine the factors that promote smoking behaviors according to smoking status among adults with metabolic syndrome.Patients and MethodsA survey of structured self-reported questionnaires was conducted on 152 adults with metabolic syndrome. Outcome variables included cognitive motivations (self-efficacy, and perceived benefits and barriers), emotional motivation (emotional salience), and autonomous and controlled motivation based on self-determination theory. The participants were categorized by their smoking status (never smoking, quit smoking, or current smoking). Their sociodemographic and motivational factors were examined using one-way analysis of variance, analysis of covariance, and multinomial logistic regression analysis.ResultsData on 152 individuals with metabolic syndrome with a mean age of 57.5 years were included. The findings indicated that the motivational factors for the never-smoking and quit-smoking groups significantly differed from those for the current-smoking group in terms of self-efficacy, perceived benefits, perceived barriers, and autonomous motivation. Based on multinomial logistic regression with current smoking as the reference group, sex (being female, OR=57.69) and perceived barriers (OR=0.39) were the significant predictors for the never-smoking group, while autonomous motivation (OR=1.96) was the significant predictor for the quit-smoking group.ConclusionThe motivational factors for smoking behaviors varied according to the smoking status of adults with metabolic syndrome. Autonomous motivation was the significant predictor of smoking cessation for individuals who successfully quit, whereas cognitive motivation was influential in the prevention of smoking by individuals who have never smoked. Further studies are warranted to develop smoking cessation strategies, which should focus on specific motivational factors to lead effective smoking prevention programs in this population.

菸害防制多元介入計畫對於偏遠地區國小學童之成效 Effectiveness of Smoking Prevention Multicomponent Intervention for Elementary School Students in Rural Area

菸害防制多元介入計畫對於偏遠地區國小學童之成效 Effectiveness of Smoking Prevention Multicomponent Intervention for Elementary School Students in Rural Area

Factors Related to Adolescent Smoking: A Nationally Representative Cross-Sectional Study in Thailand

Objective: This study aimed to explore the individual, familial, and social factors associated with different smoking status in Thai adolescents from the 2017 Cigarette Smoking and Alcohol Drinking Behavior Survey (CSAD)
 Methods: The nationally representative sample of 6046 adolescents aged 15-19 years who took part in the 2017 CSAD in Thailand. Multinomial logistic regression analysis was conducted to explore the associations between the individual, familial, and social factors and different smoking status. 
 Results: The daily smoking and occasional smoking was 6.4% and 3.3%, respectively. Gender, alcohol use, substance use, attitudes toward smoking, exposure to secondhand smoke at home, anti-smoking social media campaign, and graphic warning labels were related to both daily and occasional smoking. Daily smoking was associated with exposure to secondhand smoke at school, restaurant, and public transport, and exposure to tobacco advertising.
 Conclusion: These findings suggest that smoking prevention intervention should particularly focus on these factors and also need to develop the anti-smoking policies for smoking prevention among adolescents.

Challenges in smoking prevention among healthcare workers

Many diseases have been reported in association with smoking, including chronic obstructive pulmonary disease, lung cancer, and coronary artery disease. Healthcare workers (HCWs) play an essential role in such campaigns being in the first-line of management of the corresponding patients. Therefore, it is essential to investigate the smoking status among HCWs to make sure adequate interventions are appropriately delivered to their patients. Unfortunately, different studies in the literature indicate that the prevalence of smoking is high among HCWs. Furthermore, adopting restricting policies against smoking has been reported to be of limited efficacy in reducing the frequency of smoking. Therefore, other pharmacological therapies have been proposed. However, the duration of the effectiveness of these modalities does not allow for favorable long-term outcomes. Accordingly, psychological interventions, web-based campaigns, and person-to-person interviews can be the most appropriate modalities to achieve better outcomes. Further investigations are still needed for further validation of the most optimal and suitable intervention.

Effects of Fire Compartmentation and Smoke Exhaust Measures on Smoke Spread Caused by Cable Fire in Utility Tunnel

Investigating the behavior of fire smoke in utility tunnel as well as smoke prevention and control measures are of vital significance for exhausting smoke from utility tunnel, realizing efficient firefighting and rescue, and guaranteeing the normal operation of cities. Taking utility tunnel as the research background, this paper builds a simulation calculation model for fire smoke prevention and control in the utility tunnel using PyroSim numerical simulation software and explores the rules of smoke spread under conditions such as building ceiling screen, changing fire compartmentation tightness, and adding smoke exhaust facilities. According to study results, before the tunnel was filled with smoke, ceiling screens lowered smoke spread rate, and smoke spread rate was inversely proportional to the ceiling screen height. When the fire door was opened, fire smoke spread to the adjacent fire compartment, and smoke spread rate was directly proportional to the fire door opening angle. Before the tunnel was filled up, mechanical smoke exhaust facilities significantly lowered the smoke spread rate by as much as 50%. When the entire tunnel was full of smoke, mechanical smoke exhaust facilities significantly reduced the smoke concentration in the utility tunnel; smoke layer temperature dropped by as much as 32°C, while visibility improved by as much as 66%. By studying smoke spread in utility tunnel, this paper aims to determine the optimal measures of preventing and controlling smoke spread in utility tunnel. This paper could also offer some reference for practical engineering applications in smoke prevention and control in utility tunnel.

Abstract 14223: Unfavorable Recent Trends in Smoking in Brazil - A Call for Innovation?

Introduction: Tobacco use is one of the leading preventable causes of death in Brazil and worldwide. In addition, tobacco consumption through different forms of smoking is associated with an increased risk of cardiovascular events. Objectives: We analyzed the prevalence of smoking among adults in Brazil, and cardiovascular mortality rates attributable to tobacco, from 1990 to 2019 Methods: The prevalence of current smokers was estimated using data from a cross-sectional, nationally representative survey (National Health Survey) and the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil) from 2006 to 2019. Age-standardized mortality rates and the absolute number of deaths attributable to tobacco were obtained from the Global Burden of Diseases 2019. Results: The results indicate that 12.8% (95% CI, 12.4-13.2%) of adults use some tobacco product, being the use higher in males (16.2%; 95% CI, 15.6-16.9%) than in females (9.9%; 95% CI, 9.3-10.3%). The proportion of people over 18 years of age who smoke in 2019 was 12.6% (95% CI, 12.2-13.0%), 15.9% (95% CI, 15.3-16.6%) in males, and 9.6% (95% CI, 9.2-10.1%) in females, showing a significant decrease in the last three decades (34.8% in 1989). However, there was an increase of 0.5% in the prevalence compared to 2018, suggesting a change in the trends. In 2019, smoking was responsible for 65,693 deaths from cardiovascular disease in Brazil (39% of all deaths attributed to tobacco). Cardiovascular mortality attributable to smoking decreased from 88.0/100,000 inhabitants (95%UI, 81.3-94.3) in 1990 to 26.3/100,000 inhabitants (95% UI, 23.8-28.9) in 2019. Conclusions: The prevalence of tobacco consumption and cardiovascular mortality attributed to tobacco has decreased in Brazil in the past three decades. However, recent opposite trends call for attention, demanding innovation in addressing the prevention and reduction of smoking in Brazil.

Роль семейных врачей в профилактике сердечной недостаточности

Актуальность. Сердечная недостаточность является опасным для жизни синдромом, требующим приоритетного рассмотрения. Сердечная недостаточность является ведущей причиной заболеваемости и смертности в развивающихся и развитых странах. Стандартизированная медикаментозная терапия является успешной на ранних стадиях сердечной недостаточности. На поздних стадиях отмечается высокая частота госпитализации из-за наличия тяжелой сердечной недостаточности и / или сопутствующих заболеваний, которые требуют адекватного индивидуализированного междисциплинарного подхода. Материалы и методы. В нашем обзоре проанализированы национальные и международные клинические руководства, рекомендации, научные статьи по проблеме профилактики сердечной недостаточности и роли в этом семейного врача. Результаты. Спектр заболеваний, предрасполагающих к развитию у пациентов сердечной недостаточности, чрезвычайно широк. Медицинские работники всех клинических дисциплин, особенно первичной медицинской помощи, должны обладать необходимыми знаниями для выявления пациентов с заболеваниями, которые повышают риск развития сердечной недостаточности, и назначать профилактические препараты. Фундаментальные принципы влияния на факторы риска у больных с сердечно-сосудистой патологией общепризнаны. Все пациенты с сердечно-сосудистым заболеванием должны получать информацию о своем заболевании, а также рекомендации по изменению образа жизни и направленному фармакологическому вмешательству с целью уменьшения модифицируемых факторов риска. Выводы. Даже у больных с выраженной сердечной недостаточностью можно предотвратить преждевременную смерть, если больные смогут распознавать симптомы и немедленно обращаться за медицинской помощью. Информирование общественности и обучение пациентов имеют большой потенциал для улучшения прогноза больных с сердечной недостаточностью.Соблюдение клинических рекомендаций также связано с улучшением результатов у пациентов с сердечной недостаточностью. Тем не менее, существуют значительные различия в следовании рекомендациям. Необходимы исследования для создания доказательной базы для определения индикаторов эффективности, характеризующих улучшение результатов пациентов в амбулаторных условиях.

The impact of a family-empowerment program on smoking prevention among elementary student in Indonesia: a cluster randomized controlled trial

ABSTRACT Smoking among adolescents is prevalent and a significant public health issue associated with premature death. Family has a vital role in smoking prevention and quitting smoking; however, parents frequently question their ability to positively influence their children in this area, believing that such advice is ignored or despised by their children. Family empowerment is important enhance the role of family participation in child care. The goal of this study was to examine the impact of family empowerment on smoking prevention. A cluster randomized controlled trial (RCT) was conducted between January to April 2020. Parallel assignment was used in this cluster RCT. Family empowerment program included five intervention steps, including needs assessment, bonding process, problem-solving, educational participation method, process and outcome evaluations. At enrollment, approximately 500 students participated (response rate was 67 % at baseline and 90 % at follow-up). The family empowerment program improved outcomes relative to the control at time one (T1) across four outcomes: 1) family empowerment increased 0.08 (95% confident of interval (CI) 0.01 to 0.15), 2) Intention to smoke score saw a modest increased 0.07 (95% CI 0.02 to 0.12), 3) self-efficacy increased 0.26 (95% CI 0.07 to 0.69) and skill to refuse also saw a modest increase of 0.19 (95% CI 0.05 to 0.37). This study takes a significant step toward establishing an empowering and low-cost approach to delivering preventive interventions, while also elevating the voice of adolescents in health policy advocacy efforts..

The Implementation Activist: How One Determined Person with a Camera Has Achieved Enforcement of Smoke-Free Laws throughout Thailand.

Smoking and exposure to secondhand smoke are leading causes of disease and premature death in low- and middle-income countries (LMICs), where over 80% of smokers live. Over 152 LMICs, including Thailand, have passed laws designating that indoor and outdoor public spaces should be smoke-free. Throughout LMICs, implementation of laws has been a persistent problem. We identified one activist in Thailand who developed his own highly effective strategy for ensuring implementation of smoke-free laws, and whose approach has potential for being a model for implementation activists in other LMICs. We set out to describe the implementation activist's strategy and impact, and to explore his perspective and motivations. We conducted in-depth interviews with the activist, reviewed video recordings and transcripts, and used narrative analysis to identify key themes and illuminating statements. In the implementation activist's assessment, administrators and officials were not being held accountable for their responsibilities to enforce laws, resulting in low public compliance. The activist developed his strategy to first identify public places where no-smoking signs were not posted and/or where people were smoking; take photographs of violations and make notes; and file citizen's complaints at police stations, submitting his photographs as evidence. The implementation activist documented over 5,100 violations of smoke-free laws throughout Thailand and reported violations to police. Often, police officers were unsure how to deal with his complaints, but when he educated them about the law, most undertook enforcement actions. The activist's work has contributed substantially to creating smoke-free schools, sports facilities and parks. This implementation activist's approach can be a model for preventing youth from using tobacco/nicotine, and preventing exposures to secondhand smoke and e-cigarette emissions. Based on his successes, we provide a list of elements that implementation activists can use to be effective, along with recommendations for policy and practice.

Effect of BMI on Prolonged Abstinence after Smoking Cessation Treatment: A Retrospective Cohort Study.

Despite the well-documented relationship between weight gain and poorer cessation outcomes among smokers, the role of the former (baseline) weight in smoking cessation is insufficiently investigated. We hypothesized that patients with higher baseline body mass index( BMI) have a worse prognosis in tobacco cessation. This retrospective clinical cohort study aimed to investigate the role of the baseline BMI on abstinence over 12 months after participation in smoking cessation treatment conducted in a middle-income country (n = 664). Data from a 6-week smoking cessation protocol performed in a Psychosocial Care Unit (CAPS) were used. The protocol included four medical consultations and six Cognitive-Behavioral Therapy (CBT) group sessions. Initially, 1,213 participants were evaluated for the study, but only the participants whose telephone contact was successful were included in the outcome analyses. The attrition rate was 45.3%. Continuous and categorical (normal, overweight, and obesity) BMI values were computed. Survival regression models were used to test the associations between BMI and the 12-month abstinence outcome. Self-report 4-week abstinence at the end of treatment was also investigated using logistic regression models. Baseline BMI had no significant effect on both short (4-week-point abstinence) and long (12-month prolonged abstinence) treatment outcomes. The possible influence of the baseline BMI on smoking cessation outcomes, especially considering prolonged abstinence, was not corroborated by our results. Regardless of our results, the detrimental health outcomes due to the combination of obesity/overweight and smoking justify that these subgroups of individuals be continuously targeted for adequate smoking prevention and treatment.

Effect of metro train on the critical driving force for preventing smoke back‐layering in tunnel fires

SummaryPreventing smoke back‐layering in longitudinal‐ventilated tunnels is an important topic in handling with fires safety issues. Previous studies focused on the critical velocity, while only very few of them paid attention to how to realize this parameter, that is, in a critical state, to overcome the resistance of the tunnel and the fire source to the airflow, the required driving force provided by the ventilation equipment installed in the tunnel. This study addressed this problem in the situation where the coupling effect of blockage and throttling effect was highlighted by conducting theoretical analysis and numerical simulations. The results showed that the presence of metro train blockage reduces the effective cross‐sectional area of the tunnel near the fire source and decreases the critical velocity. On the other hand, the blockage of trains also increases the resistance to the ventilation airflow and exacerbates the throttling effect, leading to the increase of the critical driving force. In such conditions, a stronger driving force to approach the critical velocity was needed. Besides, the length of train blockage was verified to exert limited influence on the value of critical velocity while it significantly affected the critical driving force. Furthermore, the calculated formula for the critical driving force was proposed with the prevention of smoke back‐layering considering the blockage effect to be emphasized.

Smoking enhances suicide risk-a significant role in the COVID-19 pandemic?

The COVID-19 outbreak has severely affected the whole world. Considerable evidence suggests that tobacco smoking is associated with increased severity of COVID-19 and death in COVID-19 patients. Tobacco smoking cessation is necessary to decrease COVID-19—related hospitalizations and deaths. In this commentary, I suggest that tobacco smoking cessation is also needed to reduce suicidal behavior during and after the COVID-19 pandemic. Significant evidence suggests that the COVID-19 pandemic leads to increased tobacco consumption as smokers use more tobacco to cope with pandemic related stress, anxiety, depression, and loneliness. Multiple studies have demonstrated that tobacco smoking is associated with suicidal ideation, suicide attempts, suicide death, and a contributing factor in the pathophysiology of suicide. Smoking may increase the probability of development of post-COVID syndrome because it increases severity of COVID-19. Suicide risk may be increased in individuals with post-COVID syndrome. Smoking prevention and cessation should be a target of suicide prevention interventions during and after the COVID-19 pandemic. The COVID-19 pandemic enhances the need to act to integrate tobacco smoking cessation in the health care as a standard of patient care.

Study on the Effect of Jet Direction of Compound Air Curtain on Smoke Control

High temperature smoke caused by fire is a major cause of casualties. In order to ensure the safety of personnel, it is very important to control the spread of smoke and enable personnel to quickly withdraw from the fire scene. While traditional hard isolation, such as fire doors, may hinder the safe evacuation of people, the use of an air curtain as a flexible isolation has received more and more attention from researchers. In this paper, the influence of jet direction of compound air curtain on the smoke control effect was studied, and six working conditions were designed. The temperature and smoke isolation of the compound air curtain were numerically simulated by using ANSYS FLUENT software. The parameters such as temperature, velocity pressure and velocity streamline were analyzed, and the smoke control effects of six different jet directions were discussed. The simulation results were verified by Pyrosim fire simulation software simulation software. The results show that the direction of jet flow has a significant influence on the smoke control effect, and the fire smoke control effect under working conditions 4 and 5 is better. The working condition 5 (both air curtain A and air curtain B have outward jet direction) has the best smoke prevention effect, which is suitable for a situation that is close to the fire source. Working condition 4 (outward direction of air curtain A and inward direction of air curtain B) has the second-best effect of smoke prevention, which is suitable for situations far from the fire source.

Communication via mobile phone as an effective tool of public health: Findings of MAMAmobi program

IssueThe level of timely referrals to health specialists among Russian pregnant women is low, as well as the level of preventive knowledge and health information that often is derived from unreliable sources. About 2/3 of Russian women who are smoking don't quit smoking during pregnancy and breastfeeding. There is low level of breast feeding among Russian women. During COVID -19 there is need for reliable information. Given the geography of the country, there is need for pregnant woman and mothers with a newborn for modern health service and relevant information.DescriptionProgram MAMAmobi - free mobile service for pregnant women and new mothers to delivering up-to-date health information regarding maternal and child health via all channels on mobile phones: messengers, mobile applications, YouTube, social media, Email, text msgs, etc. All the content and messages are developed and reviewed by the leading experts in the field. Each client automatically receives individual messages on her mobile phones according to her pregnancy term or a baby birthday.Results250,000 pregnant women and new mothers reached by the program annually. Program monitoring identified increasing number of women who practice breast feeding and practice healthy behaviour. Dissemination of the evidence-based information on vaccine and immunisation among the audience increase women make a rational decision. The rate of women taking folic acid is higher among women participating in the program compared to control group.LessonsCommunication via mobile phone brings the most accurate information to women, motivate them to keep their own health and babies' health, allow to deliver information on urgent issues, establish high reliability of such channel and keep adherence to the program very high.Key messages The service is a viable tool that brings improvement in women’s knowledge on maternal and child health including prevention of smoking and alcohol consumptions, COVID-19 and etc and change behaviour.The communication channels on smartphones should be changed according to expectations of the target group and available technology.

Kretek Cigarettes and Particulate Matter Emissions—An Aerosol Spectrometric Study on Typical Indonesian Brands Flavored With Cloves

Abstract Introduction In Indonesia, smoking is widespread. The same applies to second-hand smoke (SHS) exposure. More than 90% of Indonesian smokers smoke clove cigarettes, so-called Kreteks. They often contain more tar and nicotine than conventional cigarettes, but little is known about particulate matter (PM) emissions. In smokers’ homes, SHS is the main source of PM that is hazardous to health. This study presents data of PM emissions from Kreteks. Methods SHS was generated in a closed 2.88 m³ measuring chamber. PM fractions (PM10, PM2.5, PM1) of three popular Kretek brands (two king-sized and one slim-sized) in comparison to conventional cigarettes and a reference cigarette were measured by laser aerosol spectroscopy in real-time. Results The king-sized Kreteks reached PM10 and PM2.5 mean concentrations of up to about 3000 µg/m³, and PM1 mean concentrations of up to about 2700 µg/m³. Consequently, these Kreteks emitted up to about 100% more PM10 and PM2.5, respectively 84% more PM1 than the reference cigarette, and up to about 260% more PM10 and PM2.5, respectively 234% more PM1 than the other investigated cigarettes. Conclusions PM emissions from Kreteks can be very high. The Indonesian public should be informed and warned about it, considering the high prevalence of smoking and SHS exposure, in particular. The Indonesian tobacco control regulation is limited, and it is overdue to start with a serious and effective tobacco control policy. PM declaration to government authorities could be useful in smoking prevention and tobacco control. Implications Research data are limited for Kretek cigarettes, including data on particulate matter (PM). The clove buds in Kretek cigarettes are for flavoring the smoke and shall soften the smoke feeling. That makes them very popular in Indonesia, in particular. The declaration of PM data of Kreteks and other tobacco products can play a key role in a more effective tobacco policy to reduce consumption of tobacco products, not only in Indonesia. To provide data on PM emissions, this study ascertained PM amounts in passive smoke from Indonesian Kreteks.

Surgical complications after caesarean section: A population-based cohort study.

BackgroundThe rate of caesarean section without medical indication is rising but the risk for surgical complications has not been fully explored.MethodsAltogether 79 052 women from the Swedish Medical Birth Register who delivered by caesarean section only from 2005 through 2016 were identified and compared with a control group of women delivering vaginally only from the same register and the same period of time. By cross-linking data with the National Patient Register the risks for bowel obstruction, incisional hernia and abdominal pain were analysed, as well as risk factors for these complications. We also analysed acute complications, uterine rupture, and placenta praevia.FindingsCaesarean section is associated with an increased risk for bowel obstruction (OR 2.92; CI 2.55–3.34), surgery for bowel obstruction (OR 2.12; CI 1.70–2.65), incisional hernia (OR 2.71; CI 2.46–3.00), surgery for incisional hernia (OR 3.35; CI 2.68–4.18), and abdominal pain (OR 1.41; CI 1.38–1.44). Smoking, obesity, and more than one section delivery added significantly to the risk for these complications.InterpretationCaesarean section is considered a safe procedure, but awareness of the risk for serious complications is important when deciding on mode of delivery. In this study, more than one section, obesity and smoking significantly increased the risk for complications after caesarean section. Prevention of smoking and obesity among fertile women worldwide must continue to be a high priority.

A study on longitudinal distribution of temperature rise and carbon monoxide concentration in tunnel fires with one opening portal

The high temperature and CO concentration are the main factors leading to fatalities and injuries when a fire occurs in the tunnel. Based on the research results of smoke characteristics in tunnel fires, the longitudinal distribution of temperature rise and CO concentration in tunnel with one opening portal were theoretically analyzed and compared, and their longitudinal distribution as well as the variation law of their differences was obtained by using Fire Dynamics Simulator (FDS) for numerical simulation in one-dimensional horizontal diffusion stage. The results show that, without ventilation, the temperature rise decays as an exponential function, and the CO concentration decays as a power function, while the difference between them increases as an exponential function. The decrease in temperature rise and CO concentration is negatively correlated with the fire heat release rate, but the increase in the difference between the two is opposite. The result is in the same form as the longitudinal distribution laws at natural opening condition. The research conclusion will be helpful to the design of tunnel smoke prevention and exhaust engineering, as well as the management of evacuation and rescue.