Influence of emission from rice straw burning on bronchial asthma in children

Background: Emission from rice straw burning (ERSB) is observed everywhere after harvest of rice in Niigata Prefecture every year. Pediatricians and many guardians in this district have had the impression that ERSB may induce asthma attack. Recent studies have suggested that particulate air pollution plays a role in the exacerbation of asthma. The authors investigated relationship of ERSB to asthma attack in children. Methods: A questionnaire on rice straw burning (RSB) was circulated to guardians and pediatric institutions. Change in the monthly number of children with asthma attack (CAA) for 5 years from January 1994 to December 1998 was investigated. In addition, change in the number of CAA from the meteorologic conditions and RSB was investigated from the fourth week of August to the third week of September in 1996, 1997 and 1998. Challenge test exposure to ERSB was tried on a volunteer adult with chronic asthma. The situation of air pollution was examined by measuring suspended particulate matter (PM10). The relationship between PM10 and the number of CAA was studied. Results: A majority of the guardians had the impression that ERSB induces asthma attack. Pediatricians replied similarly to the questionnaire. The number of CAA visiting our emergency room and admitted to our ward increased in the season of RSB. The PM10 had a significant correlation with the number of CAA. It was suggested that the increase in CAA may be not due to the meteorologic conditions, but to the influence of ERSB. Conclusion: The ERSB has made an issue of air pollution. Furthermore, the possibility that ERSB induces or exacerbates asthma attack has become clear in the present study. Therefore, it is recommended that RSB should be abolished for the health of inhabitants, especially children with asthma.