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.


OBJECTIVE
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); β= -0.104, p=0.020) and forced expiratory flow at 25% of forced vital capacity (FEF(25); β= -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.
School of Public Health, Wuhan University, Hubei, China.
Qi-Qiang
QQ
He
Tze-Wai
TW
Wong
Lin
L
Du
Zhuo-Qin
ZQ
Jiang
Tak-sun Ignatius
TS
Yu
Hong
H
Qiu
Yang
Y
Gao
Andromeda H S
AH
Wong
Wei-Jia
WJ
Liu
Jia-Gang
JG
Wu
D000293:Adolescent; D002648:Child; D002681:China; D015331:Cohort Studies; D003625:Data Collection; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008450:Maximal Midexpiratory Flow Rate; D011446:Prospective Studies; D012129:Respiratory Function Tests; D012140:Respiratory Tract Diseases / Q000453:epidemiology*; D012907:Smoking / Q000453:epidemiology*; D013147:Spirometry; D014028:Tobacco Smoke Pollution / Q000009:adverse effects*
D014028:Tobacco Smoke Pollution