peak expiratory flow changes among welders

more than one percent of the labor force in each country consists of welders exposed to various damages caused by welding. the number of studies conducted in this field is low, especially in iran. in this paper, we tried to discover any temporary and reversible obstructive effect of welding fumes on the respiratory systems of welders. in this cross-sectional study, peak expiratory flow rates and respiratory symptoms of 37 welders during work shift were evaluated. peak expiratory flow rates of welders were recorded in three working days and one non-working day. peak expiratory flow rates in working days were compared with non-working peak expiratory flow rates as a control measure. pef values were higher in every recorded time in non-working days than that of working days. besides, pef of the middle shift decreased an hour after end of the shift had increased. changes in pef since the start of shift until an hour after the shift had the same pattern in all four days, but in conflict with daily physiological patterns. fewer people complained respiratory symptoms such as cough and sputum in non-working days. therefore, exposure to the welding fumes can result in reversible and temporary effect on pef and this could lead to bronchial irritation and cause respiratory symptoms. therefore, it is recommended that welders use sufficient respiratory protection and weld in places with air ventilator specialty when welding with co 2 in order to reduce irritant effects of welding fumes on respiratory systems.