| Air pollution is one of the most serious problems of public health today. Estimated by the WHO, air pollution causes about 3 million deaths each year, directly or indirectly, which account for about 5 percent of annual global deaths. At present, the relationship between air pollution and the development of respiratory diseases is a hot subject which attracts global attention. However, researches focusing on it have achieved results of great diversity, which may result from the difficulty to define a stable exposure - dose relationship among studies. In Liaoning Province, air pollution levels have significant variety among cities, thus make it an ideal "laboratory" for researches. Water and heat are supplied by district heating systems and coal or coal gas is used for cooking. Cooking smoke serves as a major source for indoor air pollution. We found it necessary to investigate the risk factors such as smoking, indoor decoration, indoor combustion (e.g. , gas cooking, coal heating) and ventilation on the respiratory health of people living in Northern China.Subjects and methodsThe study population comprised 36,704 people from six cities in Northern China ( e. g. , Shenyang, Anshan, Benxi, Dandong, Liaoyang, Panjin). In each city, 3 areas were selected to represent a severely polluted area, a moderately polluted area and lightly polluted area. Within each area, a kindergarten and an elementary school were selected in the proximity of the air monitoring sites (less than 1000 meters). Students in kindergartens and elementary schoolwere subjects of this study, their parents and grandparents were also enrolled. The survey instrument included a standardized questionnaire adapted from the A-merican Thoracic Society Epidemiologic Standardization Project questionnaire, which had been slightly modified according to the Chinese population. The questionnaire was composed of followings: age, sex, breast -feeding, years of residence , characteristics of house, indoor decoration, method of cooking and heating , place of kitchen, house ventilation devices (if any) , cooking smoke, history and current status of children ï¿¡ respiratory illnesses and symptoms, parental education levels, parental occupation, parental smoking and parental respiratory health history and so on.The data were analyzed using SAS statistical softare (version 6. 12;SAS Institute, Inc. , Cary, NC). The odds ratio ( OR) was used as a measure of effect between the outcome and exposure. We calculated adjusted ORs and 95% confidence intervals ( CI) in logistic regression analysis. Cochran - Mantel -Haensel ^2 test was used to determine the existence of linear trend in the variables.Results and conclusionTSP, SO2 concentrations have gradually decline in recent years, while the level of NOx is fluctuating. Air pollution is still s serious problem, not accord with the national standard.The prevalence of respiratory symptoms in males in six Liaoning cities was;cough, 3.45%;persistent cough, 5.37%;asthma, 0.92%;wheeze, 2.41%. In female, the rate was;cough, 1. 16%;persistent cough, 2. 16%;asthma, 0. 82%;wheeze, 1. 81%. The prevalence was high in spring and winter, while low in May to September.We found respiratory allergy increased in association with the home being adjacent to traffic. Pollution source around house was a risk factor for persistent cough, wheeze, and wheeze symptom. Exposure to furry pets was associated with higher reporting of persistent cough and persistent phlegm, and there was a positive and significant association between house decoration and the adjustedodds ratios for asthma symptom and wheeze. House coal use was not associated with health outcomes except for persistent phlegm. Smoking and passive smoking" were associated with higher reporting of respiratory morbidity. The level of N02 was a risk factor for higher morbidity.
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