In China, a respiratory health study was conducted in the three cities of Lanzhou, Wuhan and Guangzhou with
different air pollution levels. Respiratory health parameters of parents and children were measured, and significant
and strong effects of air pollution, by district, were found on prevalence rates of cough, phlegm, persistent cough
and phlegm, and wheeze for both the mothers and the fathers. In addition, the odds ratios increased as ambient total
suspended particle concentration increased across the 3 urban districts (41). There was also a positive and significant
association between total suspended particle levels and the adjusted odds ratios for cough, phlegm, hospitalization
for diseases, and pneumonia in children. Furthermore, parental smoking status was associated with cough and
phlegm, and use of coal in the home was associated only with cough prevalence (42). A study from Beijing found
significant associations between SO42- concentration and total mortality and mortality due to cardiovascular
disease, malignant tumour and lung cancer (r > 0.50 in all cases) (43). The correlations were found not only between
the current SO42- concentration and these mortalities, but also for SO42- levels measured up to 12 years prior to
death, suggesting long-term effects of air pollution. No significant associations were observed for mortality from
respiratory diseases and cerebrovascular diseases (r = 0.30—0.50). This study indicates that the concentration of
SO42- in air is a useful air pollution indicator in areas where coal is used as the main source of energy. Areas with
high levels of SO42- experienced higher mortality owing to a variety of chronic diseases