Environmental tobacco smoke exposure and Chinese schoolchildren's respiratory health: a prospective cohort study.

BACKGROUND: Although China is the most coveted cigarette market worldwide, few studies have examined the longitudinal effects of environmental tobacco smoke (ETS) on health. PURPOSE: To examine the relationship between exposure to ETS and respiratory health in Chinese schoolchildren. METHODS: The study subjects included 1718 children, who were never-smokers, aged 10.05±0.86 years and asthma-free at baseline. The children performed spirometric tests in 2006 and 18 months later. Parents reported the children's respiratory symptoms and illnesses, ETS exposure, and other related information by self-administered survey at both assessment points. The data were analyzed in 2010. RESULTS: Significant exposure-response relationships were found between ETS exposure and coughing at night (p for trend<0.001); sneezing (p for trend=0.031); and sneezing with itchy, watery eyes (p for trend=0.006) in the first survey, and coughing at night (p for trend=0.019); phlegm without a cold (p for trend<0.001); and sneezing (p for trend=0.036) in the second survey. Compared with those who reported no ETS exposure in either survey, children who had a high ETS exposure level (>5 cigarettes/day) in either survey had lower growth rates in forced expiratory flow between 25% and 75% of forced vital capacity (FEF(25-75); ß= -0.104, p=0.020) and forced expiratory flow at 25% of forced vital capacity (FEF(25); ß= -0.077, p=0.027). A monotonic exposure-response effect was observed between ETS exposure and the deficits in the growth rate of FEF(25) and FEF(25-75.) CONCLUSIONS: Exposure to ETS increased the risks of respiratory symptoms in Chinese school-aged children and was associated with impaired lung function growth. A dose-response relationship was observed for the latter effect.

Physical activity, cardiorespiratory fitness, and obesity among Chinese children.

OBJECTIVE: To investigate the relationships of cardiorespiratory fitness (CRF) and physical activity (PA) with the risk of overweight/obesity in Chinese schoolchildren. METHODS: A total of 1795 children aged 8-13 years at baseline were followed-up for 18 months from 2006 to 2008 in Guangzhou, China. Children were categorized as "normal weight", "overweight", and "obese" using Chinese obesity cut-off points. Data on self-reported PA were obtained. CRF was determined by the 20-meter multistage fitness test, and the sex-specific median values were set as the cut-off points for the classification of high and low CRF. RESULTS: Significantly higher CRF was found in children with normal weight (from 6.55 to 8.65 ml/kg/min) or physically active children (from 0.42 to 1.22 ml/kg/min) compared with the reference group. CRF was inversely associated with the kg/m(2) change in BMI during the follow-up period (ß=-0.63 kg/m(2) and -0.64 kg/m(2) for boys and girls, respectively, both p<0.001). Significant association of baseline CRF with overweight/obesity was found in boys (odds ratio (OR) 8.71; 95% confidence interval (CI) 2.59-29.26, p<0.001), whereas the association was marginally insignificant in girls (OR 6.87; 95% CI 0.96-49.09, p=0.055). CONCLUSIONS: The results showed a strong negative association between CRF levels and children's BMI and weight gain.

Effects of ambient air pollution on lung function growth in Chinese schoolchildren.

OBJECTIVE: To evaluate the adverse effect of exposure to air pollution on lung function growth in school-aged children. METHODS: A cohort of 1983 children from three districts in Guangzhou, China was followed-up for 6 months. The children performed pulmonary function tests twice, and their parents reported the child's respiratory symptoms by self-administered questionnaires in both surveys. RESULTS: The annual mean concentrations of air pollutants for the past 5 years for particulate matter less than 10 microns in diameter (PM(10)), nitrogen (NO(2)), and sulfur dioxide (SO(2)) were respectively: 96.1 microg/m(3), 76.0 microg/m(3), and 65.7 microg/m(3) in the highly-polluted district (HPD), 80.3 microg/m(3), 67.6 mug/m(3), and 54.5 microg/m(3) in the moderately-polluted district (MPD), and 80.0 microg/m(3), 48.1 microg/m(3), and 52.2 microg/m(3) in the least-polluted district (LPD). After adjustment for potential confounders, significant deficits were found in the annual growth rates of forced expiratory flows at 25% (FEF(25)), and between 25% and 75% (FEF(25-75)) in boys and FEF(25) in girls (In boys, for FEF(25), -0.136 l/s, p = 0.008 in MPD and -0.153 l/s, p = 0.004 in HPD, respectively; for FEF(25-75), -0.176 l/s, p = 0.013 in MPD and -0.167 l/s, p = 0.021 in HPD, respectively. In girls, for FEF(25), -0.123 l/s, p = 0.043 in HPD), using LPD as the reference. Deficits in the annual growth rate of forced expiratory volume in 1 s (FEV(1)) were also negatively associated with air pollution in boys (-0.063 L, p = 0.032 in HPD). CONCLUSIONS: The study adds more evidence that exposure to air pollution has adverse effects on lung function growth in schoolchildren.

[A matched case-control study on risk factors related to sports injuries in primary and secondary school students in Guangzhou].

OBJECTIVE: To investigate the risk factors and to provide evidence for prevention and reduction of sports injuries in primary and secondary school students in Guangzhou. METHODS: 1:1 case-control study was conducted on both 349 cases and controls under the same distribution of sex, age and grade. Conditional univariate and multivariate logistic regression were used to explore the relationships between risk factors and injuries. RESULTS: Severe soles wear (OR = 7.20, 95%CI: 2.37 - 21.84), tiredness (OR = 14.34, 95%CI: 2.29 - 89.66) or sickness (OR = 1.96, 95%CI: 1.29 - 3.06) when participating in sports at a high frequency and history of previous injuries (OR = 2.11, 95%CI: 1.41 - 3.96) were risk factors related to sports injury while guidance by teachers and physical education provided by teachers during training (OR = 0.46, 95%CI: 0.26 - 0.79), appropriate protection (OR = 0.36, 95%CI: 0.20 - 0.64) as well as warming-up exercise (OR = 0.31, 95%CI: 0.14 - 0.67) at a high frequency were protective factors for sports injury. CONCLUSION: Prevention and control on sports injury need to improve the awareness on sports safety for students and teachers in order to develop positive behavior on sports safety.

[Time domain terahertz spectroscopy of (Pb,La)TiO3 ferroelectric thin films].

Terahertz time-domain spectroscopic technique was applied to investigate the spectral properties of (Pb, La)TiO3 (PLT) ferroelectric thin films prepared on SiO2/Si substrates. The terahertz spectra of three kinds of PLT thin films with different sintering temperatures were observed. According to the experimental data, the absorption coefficients, refraction indexes and dielecric constants of the PLT thin films were computed, and the experimental results of the three kinds of PLT thin films with different sintering temperatures in the effective frequency range were compared. The results indicated that the PLT thin films had strong absorption in the frequency range of measurement, and had an obvious absorption peak at 1.5 THz and a weaker absorption peak at 2.25 THz.

Respiratory health in overweight and obese Chinese children.

OBJECTIVES: Childhood obesity has been suggested to be associated with asthma and impairment of pulmonary functions, but the findings are conflicting. The aim of this study was to examine the relationship of body mass index (BMI) with asthma, asthma-like symptoms, and lung functions in Chinese schoolchildren. METHODS: Data from a survey of 2,179 children aged 10.04 +/- 0.85 years in Guangzhou, China were analyzed. Children's history of respiratory symptoms/diseases and other potential confounders were obtained by standardized questionnaires. Anthropometric and spirometry tests were performed in all subjects. Children were categorized as "normal weight," "overweight," and "obesity" using Chinese Obesity cut-off points based on age- and gender-specific BMI values. RESULTS: Being overweight was significantly associated with an increased risk of cough with cold (odds ratio, OR 1.60; 95% CI 1.01-2.55) in boys, and phlegm with cold (OR 2.46; 95% CI 1.25-4.85) and cough without cold (OR 2.91; 95% CI 1.05-8.08) in girls. Being obese was positively associated with an increased risk of phlegm with cold (OR 1.69; 95% CI 1.04-2.87) in boys, and wheezing (OR 3.82; 95% CI 1.28-11.42) and wheezing with cold in girls (OR 8.75; 95% CI 2.11-36.34). The forced vital capacity (FVC) increased with BMI in all children, overweight boys and obese girls also had significantly higher forced expiratory volume in 1 sec (FEV(1)) than those with normal weight. CONCLUSIONS: Our findings demonstrate that overweight and obesity are high risks for children's respiratory symptoms and diseases. Pulmonary function was not adversely affected by obesity in schoolchildren.

[Lead levels in children after 10-year use of unleaded gasoline in Guangzhou municipality].

OBJECTIVE: To investigate the blood lead levels (BLLs) in children after 10-year use of unleaded gasoline in Guangzhou and evaluate the effect of this measure. METHODS: Through stratified random sampling method, 4 kindergartens and 4 elementary schools were selected from each of three districts among 12 districts of Guangzhou. Totally 2373 children were recruited into this survey and 1-2 ml blood was sampled from each child through vein. The lead concentration in blood samples was determined with Inductively Coupled Plasma Mass Spectrometry (ICP-MS) after diluted with 0.1% Triton X-100 and 0.1% HNO(3) in the ratio of 1:20. RESULTS: Among 2373 children, the highest BLL was 330 microg/L, while the lowest was 10 microg/L. Geometric mean (GM) of BLL was 58.28 microg/L with 61.11 microg/L of male and 55.37 microg/L of female (t=8.671, P=0.000). Sixty (2.51%) children were identified as elevated BLLs (>or=100 microg/L), including 36 (2.90%) male and 24 (2.09%) female (chi2=1.594, P=0.207). Compared to the surveys conducted in China 10-year ago, the children with elevated BLLs decreased 96.28% and the GM of BLLs reduced 58.37%. BLLs in suburb children (60.33 microg/L) were higher than those in downtown (58.09 microg/L) or in countryside (56.72 microg/L). CONCLUSION: The BLLs in children and the ratio for children with elevated BLLs, had declined dramatically after 10-year implement of unleaded gasoline in Guangzhou.