RESUMO
This study aimed to investigate the effects of PM10 concentrations exceeding the Thai national standard (24-hr average, >120 microg/m3) on daily reported respiratory symptoms and peak expiratory flow rate (PEFR) of schoolchildren with and without asthma in Bangkok. The 93 asthmatic and 40 nonasthmatic schoolchildren were randomly recruited from a school located in a highly congested traffic area. Daily respiratory symptoms and PEFR of each child were evaluated and recorded in the diary for 31 successive school days. During the study period, 24-hr average PM10 levels ranged between 46-201 microg/m3. PM10 levels exceeded 120 microg/m3 for 14 days. We found that when PM10 levels were >120 microg/m3, the daily reported nasal irritation of asthmatic children was significantly higher than when PM10 levels were < or =120 microg/m3. In addition, when PM10 levels were >120 microg/m3, nonasthmatic children had a significantly higher daily reported combination of any respiratory symptoms. PEFR did not change with different ambient PM10 levels in both groups. This study suggests that elevated levels of PM10 concentrations in Bangkok affect respiratory symptoms of schoolchildren with and without asthma.
