4. Discussion
We found that a garbage station, noise or heating company in 100m around the home is the risk factor of respiratory diseases in primary school students. Additionally, lung function measures decreased among children who lived in homes with a garbage station and noise within 100 meters. The respiratory tract irritant gases can be produced by the fermentation of garbage18-20, the combustion of the garbage can cause a higher mutagenicity and polycyclic aromatic hydrocarbons (PAH) contents in the air21. PAH compromises the normal developmental process of respiratory airways and mutagenicity can activates the activity of PAH, they are associated with depressed lung function in children22,23. Similarly, The inhalable particulate matter (IPM) produced by the burning fuel of the heating company is stronger associated with respiratory diseases24-26. Exposure to noise facilitates diseases, children who have been exposed to traffic noise and air pollution for a long time may have more adverse health effects than exposure to air pollution alone27. In our study, noise is a risk factor for respiratory diseases, and the reason may be that stress is a co-factor.
The analysis of the family environment showed that purchase furniture within a year, passive smoking, anophelifuge and disinfectant may also cause respiratory diseases in primary school students, and passive smoking was associated with lower FVC and FEV1. Hazardous respiratory effects can be produced in the furniture production, the cough and short breath of the furniture decoration students were obviously higher than that of the control group28. In the short period of purchase of furniture hazardous respiratory effects still exist, the incidence of respiratory diseases was increased while buying new furniture 29. Passive smoking is known as a risk factor for lung cancer30,31. The results of our study suggested that passive smoking also changes lung function. Many studies have reported that humidifier disinfectants(HDs) independently increased the risk of acute lobar pneumonia and asthma in children32-34, our study added to the evidence that disinfectants are harmful to the respiratory system. People rarely think of anophelifuge when it comes to respiratory disease, which may be caused by the lack of direct study of anophelifuge. Our research made up for this and showed that anophelifuge is a risk factor for respiratory diseases.
Although the distance from home to main traffic road, the frequency of opening windows in winter and the main fuel for cooking in winter are not the factors affecting the respiratory disease in our study, they may cause changes in the lung function. Close to the main traffic road may cause FVC decline and low frequency of opening windows in winter may cause decline in V25. Other studies have also reported the effect of distance from home to main traffic road on lung function35-37. Additionally, we found that comparing with the use of electric power, liquefied gas and pipeline gas, children in families with liquid gas have decreased lung function measures.
Overall, our study suggested that the environmental risk factor can be assessed by questionnaire to determine their impact on the respiratory system. Appropriate reduction or elimination of these environmental risk factors could help reduce the effect of this risk38,39. Therefore, closely attention should be paid to these environmental risk factors to protect the health of respiratory system. Some limitations still in our study: (1) Environmental risk factors are determined by questionnaire rather than on-site exposure assessment. (2) This is a cross-sectional study with the limitations of cross-sectional study. (3) There may be some residual miscellaneous factors that have not been obtained through the questionnaire. Further studies for these additional risk factor with detailed exposure assessment are needed.