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Summary Background Since 2013, Hong Kong has sustained the world's highest life expectancy at birth—a key indicator of population health. The reasons behind this achievement remain poorly understood but are of great relevance to both rapidly developing and high-income regions. Here, we aim to compare factors behind Hong Kong's survival advantage over long-living, high-income countries. Methods Life expectancy data from 1960–2020 were obtained for 18 high-income countries in the Organisation for Economic Co-operation and Development from the Human Mortality Database and for Hong Kong from Hong Kong's Census and Statistics Department. Causes of death data from 1950–2016 were obtained from WHO's Mortality Database. We used truncated cross-sectional average length of life (TCAL) to identify the contributions to survival differences based on 263 million deaths overall. As smoking is the leading cause of premature death, we also compared smoking-attributable mortality between Hong Kong and the high-income countries. Findings From 1979–2016, Hong Kong accumulated a substantial survival advantage over high-income countries, with a difference of 1·86 years (95% CI 1·83–1·89) for males and 2·50 years (2·47–2·53) for females. As mortality from infectious diseases declined, the main contributors to Hong Kong's survival advantage were lower mortality from cardiovascular diseases for both males (TCAL difference 1·22 years, 95% CI 1·21–1·23) and females (1·19 years, 1·18–1·21), cancer for females (0·47 years, 0·45–0·48), and transport accidents for males (0·27 years, 0·27–0·28). Among high-income populations, Hong Kong recorded the lowest cardiovascular mortality and one of the lowest cancer mortalities in women. These findings were underpinned by the lowest absolute smoking-attributable mortality in high-income regions (39·7 per 100 000 in 2016, 95% CI 34·4–45·0). Reduced smoking-attributable mortality contributed to 50·5% (0·94 years, 0·93–0·95) of Hong Kong's survival advantage over males in high-income countries and 34·8% (0·87 years, 0·87–0·88) of it in females. Interpretation Hong Kong's leading longevity is the result of fewer diseases of poverty while suppressing the diseases of affluence. A unique combination of economic prosperity and low levels of smoking with development contributed to this achievement. As such, it offers a framework that could be replicated through deliberate policies in developing and developed populations globally. Funding Early Career Scheme (RGC ECS Grant #27602415), Research Grants Council, University Grants Committee of Hong Kong.

Preventing adolescent smoking is important as smoking is typically initiated by young people. This article reviews the prevalence, psychosocial correlates, and prevention of smoking in Hong Kong adolescents. The past 30-day smoking prevalence in adolescents decreased from 9.6% in 2003 to 2.5% in 2017. Tobacco advertisements, parental and best friends smoking, nonintact families, poor family relationships, lower socioeconomic status, being a new immigrant, poor knowledge of smoking-related harm, positive attitudes toward smoking, overestimation of peer smoking, and depressive symptoms were positively associated with smoking outcomes, whereas positive youth development, authoritative mother and permissive father, family functioning, school competence, and stronger tobacco industry denormalization beliefs were protective against smoking. Along with tobacco tax increase, ban on tobacco advertisements, smoke-free law and pictorial warnings, educational efforts through theater performances, social norms campaigns, and positive adolescent training programs have been conducted to prevent adolescent smoking. To achieve the ultimate goal of tobacco endgame, further tax increase, plain packaging, banning point-of-sale display of tobacco products, smoke-free area extension, and raising minimum age of purchase should be implemented. The government proposed law to ban e-cigarettes, and heated tobacco products should be passed soon to protect children and adolescents from using these products.

The role of family relationship in adolescent use of emerging tobacco products, which have become increasingly popular, is unknown. We examined the associations of perceived family relationship quality with current use of poly-tobacco products including cigarettes, electronic cigarettes (e-cigarettes), waterpipe and smokeless tobacco in adolescents.Data from a representative sample of 42,250 US grade 7-12 equivalent students (mean ± SD age 14.6 ± 1.9 years; 51.3% boys) from 75 randomly selected secondary schools in Hong Kong (2012-13) were analysed. Logistic regressions yielded adjusted odds ratios (AORs) for current (past 30-day) use of cigarettes, e-cigarettes, waterpipe, smokeless tobacco and poly-tobacco (≥2 products) in relation to perceived family relationship quality, adjusted for age, sex, perceived family affluence, parental education, family structure, parental and sibling smoking and secondhand smoke exposure at home. Subgroup analyses were conducted to compare the associations in early (aged ≤14 years) versus late (14) adolescents.The odds of current use increased with worse perceived family relationship quality with AORs (95% confidence interval) of up to 2.92 (2.32-3.68) for cigarettes, 7.28 (4.71-11.2) for e-cigarettes, 5.04 (3.44-7.40) for waterpipe, 8.09 (4.87-13.4) for smokeless tobacco and 5.25 (3.45-8.01) for poly-tobacco products use (all P for trend.001). The associations for all tobacco use outcomes were stronger in early than late adolescents (all P for interaction.001).Dose-response relationships were found between negatively perceived family relationship quality and current poly- and individual tobacco product use by Hong Kong Chinese secondary students. The associations were stronger for alternative tobacco products and in early adolescents.

Introduction We explored the role of rejection of parental smoking in the association between parental smoking and smoking in adolescents. Methods In 2010–11 cross-sectional survey, 61,810 Hong Kong secondary school students (mean age 14.6 years, 50.5% boys) reported their smoking (never, not susceptible; never, susceptible; ever, not current; current), paternal and maternal smoking, and whether they accepted paternal and maternal smoking (acceptance/rejection). We used multinomial logistic regression to estimate the odds ratios (ORs) and 95% confidence intervals (CIs) of students' smoking in relation to acceptance and rejection of parental smoking, compared with no parental smoking. Results The OR (95% CI) of “never, susceptible”, “ever, not current”, and “current”, compared with “never, not susceptible”, in relation to acceptance of paternal smoking was 1.81 (1.67–1.96), 2.46 (2.25–2.69), and 2.79 (2.51–3.10), respectively. The corresponding ORs for rejection were 0.70 (0.64–0.76), 1.23 (1.13–1.35), and 0.47 (0.40–0.56). The OR (95% CI) of “never, susceptible”, “ever, not current”, and “current”, compared with “never, not susceptible”, in relation to acceptance of maternal smoking was 2.05 (1.80–2.33), 2.57 (2.29–2.88), and 6.33 (5.39–7.44), respectively. The corresponding ORs for rejection were 0.85 (0.69–1.05), 1.59 (1.39–1.81), and 2.14 (1.71–2.68). No overlapping was observed between the 95% CIs for acceptance and rejection of paternal or maternal smoking. Conclusions While adolescent smoking was associated with parental smoking, especially in those who accepted parental smoking, the association was attenuated or reversed in those who rejected parental smoking.

Childhood obesity may be related to school environment, but previous studies often focused on food environment only. This study aimed to examine the relationship between school physical activity environment and childhood obesity.This is a cross-sectional study with multilevel data collected on school physical activity environment using teacher questionnaires, students' growth, and obesity status from electronic health records, and neighborhood socioeconomic status from census data.This study included 208 280 students (6-18 years of age) from 438 schools (45% of Hong Kong). Prevalence of obesity was 5.0%. After controlling for socioeconomic status and intraschool correlation, robust Poisson regression revealed a reduced obesity risk associated with higher teachers' perceived physical activity benefits (risk ratio 0.96, 95% CI 0.94-0.99, P = .02), physical activity teaching experience (0.93, 0.91-0.96, P .001), school campus size (0.93, 0.87-0.99, P = .02), physical activity ethos (0.91, 0.88-0.94, P .001), number of physical activity programs (0.93, 0.90-0.96, P .001), and physical activity facilities (0.87, 0.84-0.90, P .001). Students in schools with at least 3 physical activity-friendly environmental factors (11.7%) had a much lower risk of obesity (0.68, 0.62-0.75, P .001) than those without (23.7%).A physical activity-friendly school environment is associated with lower risk of obesity. School physical activity environment should be considered in future epidemiologic and intervention studies.

Objective To investigate the association between reported alcohol drinking and mental health problems in Hong Kong adolescents. Methods In a school-based questionnaire survey in 2012-13 on 4620 Secondary one (US Grade seven) to six students (mean age 14.5, SD 1.6 years; 53.4% boys), alcohol drinking was classified as never drinking (reference), experimental, former, less-than-weekly and weekly drinking. Binge drinking was defined as drinking at least five drinks on one occasion. Mental health was assessed using the Strengths and Difficulties Questionnaire (SDQ) with five subscales (emotional symptoms, conduct problems, hyperactivity, peer relationship problems and prosocial activity) and the total difficulties score (sum of the first four subscales). Multilevel regression was used to analyse the associations of mental health problems with drinking frequency and binge drinking, adjusting for potential confounders. Results Compared with never drinking, higher total difficulties scores were associated with less-than-weekly drinking (adjusted odds ratio AOR 1.39, 95% CI 1.01–1.91), weekly drinking (AOR 3.21, 95% CI 2.18–4.70), and binge drinking (AOR 2.18, 95% CI 1.42–3.32). Weekly drinking was most strongly associated with hyperactivity (AOR 6.27, 95% CI 1.42–3.32) among all subscales. Girls were more likely than boys to report emotional problems (AOR 3.36 vs 1.47) and hyperactivity (AOR 19.2 vs 2.31) related to weekly alcohol drinking (both P for interaction Conclusions In Hong Kong adolescents, less-than-weekly, weekly, and binge drinking are associated with higher risks of mental health problems based on self-reported data. Prospective studies are warranted to explore the causality between alcohol drinking and mental health problems.

We aimed to investigate the relationship between alcohol consumption and sleep problems among Hong Kong adolescents.In the 2006 and 2007 Hong Kong Student Obesity Surveillance project, 33,692 secondary students completed an anonymous questionnaire on lifestyles and health. Alcohol consumption was categorized as nondrinkers (reference group), those who drank less than 1day per week (less than weekly drinkers), and those who drank 1 to 7 days per week (weekly drinkers, including some daily drinkers). Students reported if they had any sleep problems in the past 30 days, including difficulty initiating sleep (DIS), difficulty maintaining sleep (DMS), early morning awakening (EMA), snoring, and difficulty breathing during sleep (DBS). Insomnia was defined as any reports of DIS, DMS, or EMA. Logistic regression was used to assess the association between alcohol and each sleep problem. Multiple imputations were used to impute missing data.Compared with nondrinkers, less than weekly and weekly drinkers were more likely to report snoring with adjusted odds ratios (AOR) of 1.64 (95% confidence interval [CI], 1.40-1.92) and 1.82 (95% CI, 1.55-2.14), respectively (P.001). The corresponding figures were 1.24 (95% CI, 1.02-1.50) and 1.50 (95% CI, 1.24-1.82) for DBS (P.001) and 1.12 (95% CI, 1.02-1.22) and 1.15 (95% CI, 1.04-1.27) for insomnia (P=.002). Weekly drinking was positively associated with DMS but negatively associated with DIS and EMA. Less than weekly drinking was positively associated with DIS, DMS, and EMA.Both less than weekly drinking and weekly drinking were associated with snoring, DBS, and insomnia. The association of individual symptoms of insomnia with drinking varied with the frequency of consumption.

Purpose To investigate the association between fish consumption and mortality in 36,003 Chinese. Methods A case-control study collected 81% of all deaths of those aged 30+ from all four Hong Kong death registries in 1998. Relatives registering the deaths provided demographic, dietary and other lifestyle data for the deceased (case) and a similarly aged living person (control). Causes of death were provided by the Department of Health. Logistic regression was used to calculate the mortality odds ratios (ORs) for fish consumption adjusting for potential confounders in the 23,608 cases and 12,395 controls. Results Compared with the lowest fish consumption of less than or equal to three times a month, higher consumption of one to three times a week was associated with lower mortality ORs (95% confidence interval [CI]) of 0.75 (0.62–0.89) for all-cause, 0.66 (0.48–0.92) for ischemic heart disease (IHD), 0.70 (0.50–0.98) for stroke, 0.66 (0.53–0.82) for cancer, but not for injury and poisoning. The highest level of fish consumption of greater than or equal to four times a week also reduced mortality with ORs (95% CI) of 0.80 (0.68–0.94) for all-cause and 0.63 (0.47–0.85) for IHD. Conclusions Fish consumption significantly reduced mortality from several causes in this sample. Further longitudinal studies to confirm the association are needed.

Objective To evaluate the construct validity of the standard Chinese Short Form (SF)-12v2 in adolescents. Study Design and Setting Data collected from the Hong Kong Student Obesity Surveillance project conducted in 2006–2007 were used. The standard Chinese SF-12v2 was first evaluated against clinical criteria previously used for the evaluation of SF-12 or SF-36. The data were then randomly split into training and validation halves for exploratory and confirmatory factor analyses, respectively. Results A total of 31,357 adolescents with mean age of 14.8 years (standard deviation = 1.9; range = 11.0–18.9) were included. The standard Chinese SF-12v2 effectively distinguished groups differing in doctor-diagnosed health problems, self-reported illnesses in the past 30 days, gender, perceived health in the past 3 months, and health compared with that 12 months back. The mental health scale had low internal consistency (Cronbach's alpha = 0.34). The exploratory factor analysis was influenced by method effects, but confirmatory factor analysis confirmed the hypothesized latent structure and the one-factor structure of the SF-12v2, providing fit indices within acceptable limits. Conclusion The two components and a single general health component of the standard Chinese SF-12v2 are appropriate health indicators for Chinese adolescents.

Objectives. To examine whether habitual exercise would modify the effects of air pollution on mortality. Methods. This study included 24,053 Hong Kong Chinese who died at the age of 30 years or older in 1998. Individual information on frequency of exercise was obtained by interviewing their relatives at all four death registries. The deceased subjects were categorized as never-exercise (

Purpose The purpose of the study is to investigate the cross-sectional and prospective relation between workplace secondhand smoke (SHS) exposure and respiratory symptoms. Methods Cross-sectional data for workplace SHS exposure and respiratory symptoms were collected by using random digit dialing from 7336 never-smoking Hong Kong workers 15 years or older in 1997 to 1998. In the 2000 to 2001 follow-up, 2213 workers who remained never smoking, had the same SHS exposure status, worked at the same job for at least 2 years, and were not exposed to SHS at home at follow-up were included for prospective analysis. Results Cross-sectionally, SHS was associated significantly with frequent colds, cough and phlegm, throat problems, and the presence of any respiratory symptoms with adjusted odds ratios of 1.89 (95% confidence interval [CI], 1.66–2.15), 1.65 (95% CI, 1.35–2.02), 1.88 (95% CI, 1.63–2.15), and 1.96 (95% CI, 1.75–2.20) at baseline, each having significant linear associations with duration of exposure. SHS was not associated with rhinitis. Prospectively, consistent SHS exposure increased the risk for cough and phlegm and any respiratory symptoms by 48% (12% to 97%) and 54% (13% to 109%), respectively. Conclusions This first non-Western population-based prospective study shows that workplace SHS exposure is associated significantly with frequent respiratory symptoms, both cross-sectionally and prospectively, thus providing strong evidence that the association is causal.

In a previous study we proposed the notion of general health promotion action (GHPA) defined as "a general intention and actual practices to take action aimed to promote health." GHPA is a subjective measure of health-promoting lifestyle which may reflect practices aimed to promote health and practices which are taken for non-health reasons but which nonetheless have health benefits. The present prospective study aimed to examine whether baseline stage of change for GHPA predicted health-related lifestyle practices at 24-month follow-up in a representative community-based cohort of 3129 Hong Kong Chinese adults. Overall, 37% of the subjects remained in the same stage, 43% had progressed to later stages, and 20% had regressed to earlier stages of change at follow-up. Baseline maintainers were the most likely to report desirable lifestyle practices at follow-up. They were significantly more likely to have exercised in the past month, consumed at least 2 portions of fruit a day, consumed at least 3 portions of vegetable a day, consumed at least 5 portions of fruit or vegetable a day, have had no episodes of binge drinking in the past month, and have had a dental examination at least once a year. The association remained significant after adjusting for age, gender, education, income and baseline level of respective lifestyle practices, with significantly increasing trends from precontemplation to maintenance stage. We conclude that the predictive validity of stage of change for GHPA was supported from these longitudinal findings, and further research on how GHPA can guide health promotion strategies is warranted.

Objectives This study investigates the relation between soy consumption and mortality in a population-based case–control study in Hong Kong of all adult deaths in 1998. Methods Multivariable logistic regression was used to assess the effect of soy on all-cause and cause-specific mortality in 21,494 deceased cases and 10,968 living controls who were ethnic Chinese aged 60 or above, using proxy reports collected from the person registering the death. Dietary habits were obtained from proxies in both cases and controls, based on a 7-item questionnaire. Results The adjusted odds ratios for all-cause mortality for soy consumption 4 or more times a week compared with less than once a month were 0.77 (95% CI: 0.62, 0.95) for men and 0.66 (0.54, 0.81) for women. Mortality from lung cancer (males P = 0.02, females P = 0.02), colorectal cancer (males P = 0.07, females P P = 0.04, females P = 0.03), female breast cancer ( P = 0.02) and ischemic heart disease (males P P = 0.002) was inversely associated with soy consumption. Conclusions Our study suggests that maintaining traditional levels of soy consumption could be protective for some chronic diseases in China.

The aim of the study was to analyze the effects of sex-specific distribution of adiposity, particularly emphasizing the independent contribution of waist and hip circumferences relative to body mass index (BMI), on cardiovascular risk factors in a Chinese population. Blood pressure and anthropometric and biochemical parameters were measured in 2510 population-based Chinese subjects. The relative contributions of waist and hip circumferences to the presence of cardiovascular risk factors were determined. The Chinese men were significantly larger than women, with greater BMI and central adiposity. Waist and hip circumferences were both positively associated with the presence of hypertension, dyslipidemia, and diabetes. However, after adjustment for BMI and age, hip circumference exhibited a significant dose-dependent inverse relationship with dyslipidemia and diabetes in women, but not men. Sex-specific differences exist. After adjustment for age and BMI, hip circumferences independently and inversely contribute to cardiovascular risk in women, but not in men. Increasing adjusted waist circumference was associated with increased risk of hypertension and diabetes in Chinese and dyslipidemia in women only.

To assess the prevalence of the metabolic syndrome disease cluster in the Hong Kong Chinese population we applied the US National Cholesterol Education Programme Adult Treatment Panel III (NCEP ATP III) guidelines. This was present ifor =3 of the following conditions were present: Hypertension (or =130/85 mmHg); fasting plasma glucose wasor =6.1 mmol/L; fasting plasma triglyceridesor =1.69 mmol/L; fasting HDL-cholesterol1.04 or1.29 mmol in males and females, respectively; or subjects were receiving treatment for their condition; waist circumference88 or 102 cm (Asian WHO criteriaor =80 or 90 cm) in females and males, respectively. A total of 16.7% (17.1 (95%CI 15.7-18.5)% age and gender-adjusted) of the 2893 subjects had the metabolic syndrome. The prevalence of having at least 2, 3, 4 or 5 components was 34.5, 16.7, 6.4 and 1.4%, respectively. The prevalence increased from 3.1% in those aged 25-29 years to 41.0% in those aged over 70 years. Using the 2001 Census, 880,499 Hong Kong residents would have the metabolic syndrome. If the WHO recommended waist circumference for Asians is used, the age and gender-adjusted prevalence is significantly higher at 21.2% (21.9 (95%CI 20.4-23.4)%). In summary, the high prevalence of the metabolic syndrome in adult Hong Kong Chinese, particularly in the elderly, forewarns a rapidly increasing problem in Mainland China, and other Asian populations, which may have overwhelming public health ramifications.

Physical activity is associated with longevity; however, whether these beneficial effects extend to Chinese populations is unclear. We examined the relationship between leisure time physical activity (LTPA) and mortality in Hong Kong.Using a case-control study, past (10 years prior) levels of LTPA were ascertained via proxy informants for 24,079 dead cases (81% of all registered deaths) and 13,054 live controls aged #10878;35 years and were analyzed by unmatched logistic regression to determine their association with all-cause and cause-specific mortality.Compared with an exercise frequency of1 episode per month,or = 1 episode of LTPA per month was inversely associated with all-cause mortality [multivariable odds ratio (OR)=0.63, 95% confidence interval (CI), 0.59, 0.68 for males; OR=0.75, 95% CI, 0.70, 0.80 for females; adjusted for age, education, smoking status, alcohol consumption, and physical demand at work]. Each activity level above the reference level of1 episode per month (i.e., 1 episode per month to 1-3 episodes per week,or = 4 episodes per week) had approximately the same level of risk reduction and no dose-response gradient was observed. The inverse association was stronger for cardiovascular than cancer deaths, particularly in males and was strongest for respiratory mortality. One-fifth of all 31,349 registered deaths in those aged 35 years and over in Hong Kong in 1998 were attributable to physical inactivity.The present data confirm and extend previous findings in Caucasian populations on the association between leisure time physical activity and longevity. The population attributable risk from physical inactivity exceeds that due to tobacco smoking in this Hong Kong Chinese population. We predict mainland China will witness a similarly large mortality burden as it undergoes further socioeconomic development in the next few decades.

Background: We propose general health promotion action (GHPA) to represent the general intention and actual practices aimed to promote health. The transtheoretical model (TTM) has not been applied to GHPA. The objectives of this study were to determine whether TTM can be applied to Chinese adults by measuring the subjects' stage of change for GHPA, and to study whether stage for GHPA is associated with health-related lifestyle practices. Methods: Randomly selected Hong Kong Chinese subjects (3233) aged 18–64 were interviewed in telephone survey. Results: Thirty-nine percent had not taken any health promotion actions and had no intention to do so (precontemplation). Twelve percent had taken action but had no intention to continue (at-risk for relapse). Three percent had not taken any actions and intended to do so in the next 6 months, but not in the next 1 month (contemplation). Eleven percent had not taken any actions but intended to do so in the next 1 month (preparation). Fifteen percent had been taking action for less than 6 months and intended to continue (action). Twenty-one percent had been taking action for at least 6 months and intended to continue (maintenance). Precontemplators were less likely than maintainers to be never smokers (OR = 0.62; 95% CI = 0.49–0.80), exercisers (0.097; 0.077–0.12), to eat fruit twice a day (0.53; 0.41–0.69) and remove fat when eating (0.72; 0.54–0.95), with increasing trends in the odds of reporting these practices from precontemplation to maintenance. Conclusions: Our findings have provided preliminary findings on the applicability of TTM on GHPA in Chinese adults with evidences of concurrent criterion validity.

This population-based cross-sectional study examined the associations between smoking and perceived health in Hong Kong. 6117 healthy Chinese (3053 men, 3064 women), aged 25–74 years, were randomly selected for telephone interviews in Hong Kong in 1994–96. Adjusted odds ratios (ORs) of having poor or very poor perceived health (against good or very good) were calculated. In men, the ORs (and 95 percent confidence intervals) for current smokers in young (25–39) and middle age (40–59) were close to unity, but that of 1.97 (1.01, 3.85) in old age (60–74) was significantly raised. The adjusted ORs for male quitters were 1.98 (0.43, 9.14), 1.70 (0.75, 3.81) and 2.59 (1.23, 3.33) for young, middle and old age, respectively. Compared with current smokers, the adjusted ORs for quitters was 2.30 (1.07, 4.92) for those who had quit for less than 5 years, 2.02 (0.80, 5.11) for 5–9 years and 1.14 (0.47, 2.75) for 10 years or more. Among former smokers, each year of quitting was associated with 7 percent reduction in reporting poor or very poor perceived health with OR of 0.93 (0.85, 1.01). In women, the ORs were 1.95 (1.15, 3.28) for current and 1.54 (0.60, 3.94) for former smokers. In both genders combined, the overall ORs were 1.41 (1.04, 1.92) for current and 1.94 (1.27, 2.97) for former smokers. In conclusion, former smokers apparently had the worst perceived health but long-term quitting was beneficial. Overall, current smokers had worse perceived health than never smokers, but in men the excess risk was mainly observed in old age. The perceived health of smokers may have implications for the approaches used in smoking cessation.

Objective Although breakfast is associated with different benefits, breakfast skipping is increasingly common among children. This study aimed to identify lifestyle and socioeconomic correlates of breakfast skipping in Hong Kong schoolchildren. Methods 68 606 primary 4 participants of the Department of Health Student Health Service in 1998–2000 reported breakfast habit and other lifestyle characteristics using a standardized questionnaire. Height and weight were measured by trained SHS nurses. Socioeconomic data were reported by parents. In cross-sectional analysis, multivariate logistic regression was used to identify lifestyle and socioeconomic correlates of breakfast skipping. Results 3 598 subjects (5.2%) usually skipped breakfast. Breakfast skipping was associated with being overweight (Odds ratio = 1.59, 95% CI: 1.46 to 1.73) and obese (2.06, 1.80 to 2.36), and unhealthy dietary habits including more frequent junk food (1.23, 1.14 to 1.33) but less frequent fruit/vegetable (1.23, 1.13 to 1.34) and milk (1.98, 1.80 to 2.16) intake. Breakfast skippers tended to skip lunch, do less extra-curricular physical activity, watch more television and have less educated parents. Conclusions Breakfast skipping was significantly related to various health-compromising lifestyle characteristics and lower parental education. Breakfast habit can be a potential lifestyle indicator. Education programmes aimed at specific target groups should encourage regular breakfast consumption.

To study the association between exposure to secondhand smoke (SHS) and academic performance in non-smoking adolescents.A questionnaire survey of 23 052 non-smoking students aged 11 to 20 years was conducted. Information on academic performance, number of days of SHS exposure per week at home and outside the home, number of smokers at home and their relationship with the student, and sociodemographic characteristics was recorded.Students exposed to SHS at home 1 to 4 and 5 to 7 days per week were 14% (95% confidence interval, 5%-25%) and 28% (15%-41%) more likely, respectively, to report poor academic performance compared with students who were not exposed to SHS. Living with one, two, and ≥ 3 smokers, compared with no smoker, was also associated with 10% (0.1%-20%), 43% (23%-65%) and 87% (54%-127%), respectively, higher odds of poor academic performance (P for trend.001). The greatest excess risks were observed with SHS exposure from co-residing non-relatives, followed by siblings, visitors, co-residing grandparents and relatives, and parents.SHS exposure is associated linearly with poor academic performance in non-smoking adolescents, and the effect of SHS exposure at home is stronger from smokers other than the parents.