3. Result
3.1 Characteristics of study population
A total of 2419 samples included in the study and the characteristics of study population listed in Table 1. The sex ratio of study population is close to 1. The educational background of most of children’s parents are junior high school or above. The prevalence of respiratory diseases is 14.8%. In outdoor environmental factors, the noise is the most serious. Almost all families use fume exhauster during cooking, nearly half of households use natural gas, and other environmental factors are exposed in some families (Table 1). There were few differences between the pulmonary function testing subset and larger study sample in selected demographics, health outcome, and environmental exposures. So that the subset can represented the study population reasonably.
3.2 Monofactor analysis of the environmental risk factors of respiratory diseases
Significant differences were found in variables stinky ditch, garbage station, noise, heating company, purchase furniture, passive smoking, insecticide, anophelifuge, moth repellant and disinfectant between the population with respiratory diseases and no respiratory diseases (P <0.05). (Table 2)
3.3 Multivariable analysis of the environmental risk factors of respiratory diseases
Taking the respiratory diseases and no respiratory diseases as the dependent variable, the significant factors in the results of univariate analysis (stinky ditch, garbage station, noise, heating company, purchase furniture, passive smoking, insecticide, anophelifuge, moth repellant and disinfectant) as the independent variables, and the multivariate logistic regression was conducted to analyze the environmental risk factors of respiratory diseases. The Valuation of Variables was listed in Table 3.
As shown in Table 4, we found that garbage station, noise,heating company, purchase furniture, passive smoking, anophelifuge and disinfectant are risk factors of respiratory diseases (P <0.05).
3.4. Pulmonary function under different environmental conditions
As shown in Table 5, there was significant difference in V75 between garbage station and no garbage station, and the V75 of garbage station was lower than no garbage station (P <0.05); The PEF of noise was significantly lower than no noise (P <0.05); The FVC of children whose home is >150m from the main traffic road was significantly higher than <20m (P <0.05);The V25of children whose window opening in winter >3 times/week was significantly higher than 1-3 times/week (P <0.05);FVC were all significantly different between passive smoking <1 day/week or passive smoking 1-2 day/week and no passive smoking (P <0.05); FEV1of passive smoking 1-2 day/week was higher than no passive smoking (P <0.05); The FVC, FEV1 and V75 of electric power, liquid gas and pipe-line gas were all higher than natural gas (P <0.05).