Onset of respiratory symptoms among Chinese students: associations with dampness and redecoration, PM10, NO2, SO2 and inadequate ventilation in the school.

Objective

To study onset of respiratory symptoms among students in China in relation to the school and the home environment.

Methods

A two-year prospective cohort study among 1325 students in eight schools. Air pollution was measured at baseline in the schools. Respiratory symptoms and the home environment were assessed by a questionnaire.

Results

The 2-year onset was 14.3%, 23.2%, 15.4%, 4.7% and 37.3% for wheeze, daytime attacks of breathlessness, nocturnal cough, nocturnal wheeze/breathlessness and respiratory infections, respectively. The mean concentrations of PM10, SO2, NO2, ozone and CO2 in the classrooms were 129 µg/m3, 68.0 µg/m3, 43.2 µg/m3, 8.6 µg/m3 and 1208 ppm, respectively. Environmental tobacco smoke (ETS), dampness/mold at home and ozone in the classroom were associated with onset of wheeze. Onset of daytime breathlessness was associated with redecoration and dampness/mold at home and CO2 and relative air humidity (RH) in the classrooms. Dampness/mold at home, PM10, CO2 and RH in the classrooms and outdoor PM10, SO2 and NO2 were associated with onset of nocturnal cough. Onset of nocturnal wheeze/breathlessness was associated with dampness/mold at home and RH and PM10 in the classrooms. Respiratory infections were more common at higher levels of outdoor PM10.

Conclusions

Air pollution (PM10, ozone, SO2 and NO2) and inadequate ventilation flow in the classrooms (indicated by CO2 > 1000 ppm) and ETS, dampness or mold and chemical emissions from redecoration at home can increase onset of respiratory symptoms.