Seasonal changes in lung function in a farming population

To assess the changes in respiratory health from winter to summer seasons in a rural population.

A longitudinal design was used in the study.

A population-based study was conducted as part of the Environmental Pesticide Exposure and Human Health component of the Prairie Ecosystem Study (PECOS) in southwestern Saskatchewan.

In the winter season, 358 patients participated in the study. Of these patients, 234 returned for the second assessment during the summer season. After excluding 34 children aged 17 years and under, 200 adult patients were available for analysis.

Questionnaires were used to obtain information on demographic factors, smoking habits, occupational and environmental exposures, and respiratory conditions. Pulmonary function measurements were obtained using a volume displacement spirometer.

Mean ages (+/- SD) of the 106 men and 94 women participating in the study were 50.1+/-13.3 and 49.0+/-13.1 years, respectively. Mean percentage changes in maximal midexpiratory flow rate from winter to summer assessments indicated an improvement for town residents and a decline for farm residents. Mean percentage changes in the ratio of forced expiratory volume in 1 s to forced vital capacity indicated an improvement for town residents who were not engaged in farming, and increasing declines for town residents engaged in farming, farm residents not engaged in farming and farm residents engaged in farming.

Seasonal changes occurred in measurements of pulmonary function between winter and summer seasons; these changes may be related to the environmental or occupational exposures experienced by the participants during the study.