Early effects of burning rice farm residues on respiratory symptoms of villagers in suburbs of Isfahan, Iran.

Villagers residing in areas with rice farms are exposed to smoke from burning of agricultural waste that may affect respiratory health. To assess respiratory effects of this smoke-induced air pollution, a cross-sectional study has been conducted in three randomly selected villages of Isfahan rural areas. A physician-administered health questionnaire was completed for 433 male and 561 female villagers aged 1-80 years, followed by physical examinations and spirometry in symptomatic cases, before and after a rice burning episode in October 2000. Total particulate and respirable particulate maters (PM 10 was doubled during burning episode. Prevalence rates for respiratory symptoms before smoke were: recent asthma attacks (7.7%), using asthma medications (3%), sleep disturbed by dyspnea and cough (7.4%), exercise-induced cough (13.3%), which increased to 9.5, 7.1, 9.3 and 17%, respectively. Mean initial values (as percent of prediction) for; FEV1, FEV1/FVC, PEFR, and FEF25-75 were: 85.9 +/- 22.7, 81.7 +/- 8, 86.2 +/- 26.2 and 60 +/- 26.4, respectively. The mentioned values decreased to to 83.2 +/- 19.5, 76.5 +/- 10.3, 85.5 +/- 21.1 and 54.3 +/- 26.4, respectively. All of the clinical and spirometric changes were statistically significant. Study findings suggest increased respiratory morbidity associated with rice burning episodes among all people living in the area.