Hak-Kan Lai

Comprehensive smoke-free legislation and displacement of smoking into the homes of young children in Hong Kong.

Objective To investigate the effect of comprehensive smoke-free legislation in 2007 on the exposure of children to secondhand smoke (SHS) in Hong Kong. Methods Two cross-sectional questionnaire surveys were conducted, before (2006) and after (2008) the implementation of smoke-free legislation, among primary 2–4 students (equivalent to US grades 2–4) from 19 and 24 randomly selected schools, respectively. Adjusted ORs for SHS exposure at home and outside home post-legislation compared with pre-legislation were calculated. The strength of the association between SHS exposure and respiratory symptoms in each survey was used as an indirect indicator of the intensity of exposure. Results Among 3243 and 4965 never smoking students in the 2006 and 2008 surveys, the prevalence of SHS exposure in the past 7 days increased both at home (from 10.2% to 14.1%) and outside home (from 19.8% to 27.2%). Post-legislation, students were 56% more likely (p<0.01) to report SHS exposure at home coupled with an insignificantly stronger association between SHS exposure and respiratory symptoms. Similarly, students were 60% more likely (p<0.001) to report SHS exposure outside home in 2008, but the association between SHS exposure and respiratory symptoms became insignificantly weaker. Parental smoking rates were similar before and after legislation. Conclusions The prevalence of exposure to SHS at home and outside home have both increased among primary school students in Hong Kong post-legislation. Comprehensive smoke-free legislation without strong support for smoking cessation might have displaced smoking into the homes of young children.

Satellite-Based Estimates of Long-Term Exposure to Fine Particles and Association with Mortality in Elderly Hong Kong Residents

Background A limited number of studies on long-term effects of particulate matter with aerodynamic diameter < 2.5 μm (PM2.5) on health suggest it can be an important cause of morbidity and mortality. In Asia where air quality is poor and deteriorating, local data on long-term effects of PM2.5 to support policy on air quality management are scarce. Objectives We assessed long-term effects of PM2.5 on the mortality in a single Asian city. Methods For 10–13 years, we followed up a cohort of 66,820 participants ≥ 65 years of age who were enrolled and interviewed in all 18 Elderly Health Centres of the Department of Health, Hong Kong, in 1998–2001. Their residential addresses were geocoded into x- and y-coordinates, and their proxy exposures to PM2.5 at their addresses in 1 × 1 km grids were estimated from the U.S. National Aeronautics and Space Administration (NASA) satellite data. We used Cox regression models to calculate hazard ratios (HRs) of mortality associated with PM2.5. Results Mortality HRs per 10-μg/m3 increase in PM2.5 were 1.14 (95% CI: 1.07, 1.22) for all natural causes, 1.22 (95% CI: 1.08, 1.39) for cardiovascular causes, 1.42 (95% CI: 1.16, 1.73) for ischemic heart disease, 1.24 (95% CI: 1.00, 1.53) for cerebrovascular disease, and 1.05 (95% CI: 0.90, 1.22) for respiratory causes. Conclusions Our methods in using NASA satellite data provide a readily accessible and affordable approach to estimation of a sufficient range of individual PM2.5 exposures in a single city. This approach can expand the capacity to conduct environmental accountability studies in areas with few measurements of fine particles. Citation Wong CM, Lai HK, Tsang H, Thach TQ, Thomas GN, Lam KB, Chan KP, Yang L, Lau AK, Ayres JG, Lee SY, Chan WM, Hedley AJ, Lam TH. 2015. Satellite-based estimates of long-term exposure to fine particles and association with mortality in elderly Hong Kong residents. Environ Health Perspect 123:1167–1172; http://dx.doi.org/10.1289/ehp.1408264

A review of effects of particulate matter-associated nickel and vanadium species on cardiovascular and respiratory systems

Many epidemiological investigations indicate that excess risks of mortality and morbidity may vary among specific PM2.5 components. Nickel (Ni) and vanadium (V) particulate metal species may potentially be related to increasing respiratory and cardiovascular mortality and morbidity. This review focuses on exposure concentrations of these two species in various settings, their health effects based on epidemiological and toxicological studies and the underlying mechanisms. The evidence shows that environmental exposure concentrations of Ni and V in general setting are lower than the World Health Organization standard (V, 1 μg/m3/day) in 2000, or the European Environment Agency standard (Ni, 1 μg/m3/day) in 2003, but their associations with cardiopulmonary diseases can still be found. The toxicological mechanism can be explained by laboratory-based studies. Updated safe guidelines on environmental and human exposure of Ni and V are necessary in order to clarify the associations between them and cardiopulmonary diseases and provide environmental intervention policies.

Cancer Mortality Risks from Long-term Exposure to Ambient Fine Particle

Background: Few studies have assessed long-term effects of particulate matter (PM) with aerodynamic diameter < 2.5 μm (PM2.5) on mortality for causes of cancer other than the lung; we assessed the effects on multiple causes. In Hong Kong, most people live and work in urban or suburban areas with high-rise buildings. This facilitates the estimation of PM2.5 exposure of individuals, taking into account the height of residence above ground level for assessment of the long-term health effects with sufficient statistical power. Methods: We recruited 66,820 persons who were ≥65 in 1998 to 2001 and followed up for mortality outcomes until 2011. Annual concentrations of PM at their residential addresses were estimated using PM2.5 concentrations measured at fixed-site monitors, horizontal–vertical locations, and satellite data. We used Cox regression model to assess the HR of mortality for cancer per 10 μg/m3 increase of PM2.5. Results: PM2.5 was associated with increased risk of mortality for all causes of cancer [HR, 1.22 (95% CI, 1.11–1.34)] and for specific cause of cancer in upper digestive tract [1.42 (1.06–1.89)], digestive accessory organs [1.35 (1.06–1.71)] in all subjects; breast [1.80 (1.26–2.55)] in females; and lung [1.36 (1.05–1.77)] in males. Conclusions: Long-term exposures to PM2.5 are associated with elevated risks of cancer in various organs. Impact: This study is particularly timely in China, where compelling evidence is needed to support the pollution control policy to ameliorate the health damages associated with economic growth. Cancer Epidemiol Biomarkers Prev; 25(5); 839–45. ©2016 AACR.

Secondhand Smoke and Respiratory Symptoms Among Adolescent Current Smokers

OBJECTIVE: No study has ever reported the association between persistent respiratory symptoms and exposure to secondhand smoke (SHS) in adolescent smokers. The impact of SHS exposure on child health could be largely underestimated by not taking into account such effects. We investigated the association between exposure to SHS and respiratory symptoms among adolescent current smokers. METHODS: A total of 32506 students aged 11 to 20 years from 85 randomly selected secondary schools in Hong Kong completed a self-administered questionnaire that included persistent respiratory symptoms (for 3 consecutive months in the past 12 months), number of days of SHS exposure per week at home and outside home, smoking status, amount of active smoking, and other basic demographic characteristics and socioeconomic status. RESULTS: Adolescent current smokers who were exposed to SHS at home 1 to 4 and 5 to 7 days/wk were 50% (95% confidence interval [CI]: 3%–121%) and 77% (95% CI: 5%–199%) more likely, respectively, to report respiratory symptoms compared with those who were unexposed (P = .01 for trend). The corresponding figures for exposure outside home were 41% (95% CI: 3%–94%) and 85% (95% CI: 31%–161%; P = .004 for trend). Such associations were also observed among never-smokers, but they were weaker than those among current smokers (P < .01 for interaction). CONCLUSIONS: This is the first evidence that SHS exposure is associated with increased risks for persistent respiratory symptoms among adolescent current smokers. Health promotion programs should aim at SHS reduction as well as smoking cessation among adolescent smokers.

Fish Consumption and Mortality in Hong Kong Chinese-the LIMOR Study.

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.

Lung function and exposure to workplace second-hand smoke during exemptions from smoking ban legislation: an exposure–response relationship based on indoor PM2.5 and urinary cotinine levels

Background The effects of workplace second-hand smoke (SHS) on lung function remain uncertain because of a lack of objective measures for SHS exposures. Objective To determine whether an exposure–response association exists between lung function and two different markers of SHS based on indoor fine particulate (PM2.5) and urinary cotinine levels in non-smoking catering workers. Design A cross-sectional study during a 1.5-year exemption of licensed catering premises from smoke-free legislation. Participants 186 non-smoking catering workers aged 18–65 years in Hong Kong were recruited. A declared non-smoking status was accepted in workers with exhaled breath carbon monoxide levels <6 ppm and urinary cotinine levels <100 ng/ml. Main outcome measures Lung function measures of forced expiratory volume in 1s (FEV1 in litres), forced vital capacity (FVC in litres) and forced expiratory flow as 25–75% of FVC (FEF25–75 in l/s) were recorded. Results Indoor fine particulate (PM2.5) concentrations were 4.4 times as high in smoking premises (267.9 μg/m3) than in non-smoking premises (60.3 μg/m3) and were strongly associated with the probability of permitted smoking (R2=0.99). Smoking was the dominant source of particulates (R2=0.66). Compared with workers exposed to the lowest indoor PM2.5 stratum (<25 μg/m3), lung function was lower in the three higher PM2.5 strata (25–75, 75–175, >175 μg/m3) with FEV1 −0.072 (95% CI −0.123 to −0.021), −0.078 (95% CI –0.132 to −0.024), −0.101 (95% CI −0.187 to −0.014); FEF25–75 −0.368 (95% CI −0.660 to −0.077), −0.489 (95% CI −0.799 to −0.179), −0.597 (95% CI −0.943 to −0.251); and FEV1/FVC (%) −2.9 (95% CI −4.8 to −1.0), −3.2 (95% CI −5.1 to −1.4) and −4.4 (95% CI −7.4 to −1.3), respectively. Urinary cotinine was associated positively with indoor PM2.5 but negatively with lung function. Consistently lower values for lung function per unit increase of indoor PM2.5 were found. Conclusion Lung function is inversely associated with workplace SHS. Workplace exemptions and delays in implementing smoke-free policies and current moves to relax legislation are a major threat to the health of workers.

Exposure to secondhand smoke and academic performance in non-smoking adolescents.

OBJECTIVE To study the association between exposure to secondhand smoke (SHS) and academic performance in non-smoking adolescents. STUDY DESIGN 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. RESULTS 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. CONCLUSION 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.

Is Exercise Protective Against Influenza-Associated Mortality?

Background Little is known about the effect of physical exercise on influenza-associated mortality. Methods and Findings We collected information about exercise habits and other lifestyles, and socioeconomic and demographic status, the underlying cause of death of 24,656 adults (21% aged 30–64, 79% aged 65 or above) who died in 1998 in Hong Kong, and the weekly proportion of specimens positive for influenza A (H3N1 and H1N1) and B isolations during the same period. We assessed the excess risks (ER) of influenza-associated mortality due to all-natural causes, cardiovascular diseases, or respiratory disease among different levels of exercise: never/seldom (less than once per month), low/moderate (once per month to three times per week), and frequent (four times or more per week) by Poisson regression. We also assessed the differences in ER between exercise groups by case-only logistic regression. For all the mortality outcomes under study in relation to each 10% increase in weekly proportion of specimens positive for influenza A+B, never/seldom exercise (as reference) was associated with 5.8% to 8.5% excess risks (ER) of mortality (P<0.0001), while low/moderate exercise was associated with ER which were 4.2% to 6.4% lower than those of the reference (P<0.001 for all-natural causes; P = 0.001 for cardiovascular; and P = 0.07 for respiratory mortality). Frequent exercise was not different from the reference (change in ER −0.8% to 1.7%, P = 0.30 to 0.73). Conclusion When compared with never or seldom exercise, exercising at low to moderate frequency is beneficial with lower influenza-associated mortality.

Weight misperception and psychosocial health in normal weight Chinese adolescents

OBJECTIVE To investigate the association between weight misperception and psychosocial health problems among normal weight Chinese adolescent boys and girls. METHODS In the Youth Smoking Survey 2003-04, 20 677 normal weight students aged 11-18 years from 85 randomly selected schools throughout Hong Kong were analysed. Students who perceived themselves as very thin, thin, fat or very fat were classified as having weight misperception in contrast to the reference group who correctly perceived themselves as normal weight. Psychosocial health outcomes included headache, feeling stressful, feeling depressed, poorer appetite, sleepless at night, having nightmares and less confidence in getting along with friends. Logistic regression yielded adjusted odds ratios (ORs) for each outcome by weight misperception in boys and girls separately. RESULTS In girls, misperceived fatness was associated with all outcomes, while misperceived thinness was associated with poorer appetite and less confidence. Boys who misperceived themselves as very thin or fat had greater odds of all outcomes except having nightmares. In general, greater ORs were observed for misperceived fatness than thinness in girls, but similar ORs were observed in boys. Misperceived thinness and fatness accounted for 0.6% to 45.1% of the psychosocial health problems in adolescents. CONCLUSIONS Normal weight adolescents with weight misperception were more likely to have psychosocial health problems, and the associations were stronger for extreme misperceptions (i.e., very fat or very thin) in both boys and girls.