Lea Duffin

Abstract:

Over 13,000 shipyard welders in the United States are subjected to hazardous welding fume in enclosed and confined spaces with inadequate or no ventilation. The purpose of this study was to validate a training provided to shipyard workers on the effectiveness of ventilation, particularly in the dynamic shipyard environment. Training was developed using general ventilation concepts and adapting them to the shipyard. Training concepts included moving the exhaust ventilation close to the weld's plume, creating crossdrafts, and providing mixing in the space by dilution ventilation. Testing of ventilation in dynamic work environments is difficult and rarely conducted. This study tested the training concepts in the field by monitoring for welding fume concentration before and after ventilation was introduced into the space. The worker was observed while the ventilation training parameters were added or modified in the space. A personal and area DataRAM with an SKC pump measured total particulate concentrations in the worker's breathing zone and in the work space. It was found that adding an exhaust or supply blower resulted in an average of 58% decrease (range: 21-77%) in particulate concentration in the breathing zone and a 67% decrease (range: 39-86%) of particulate concentration in the space. Providing a crossdraft at the welder's breathing zone did not consistently produce a decrease in particulate concentration and instead caused a 50% increase in particulate concentration in the breathing zone and 5% increase in the space. Reductions in the variability of the exposures were also seen in all adjustments except exhaust ventilation, located on the ground. Additionally, reductions in the 90th percentiles (upwards to 90% decrease in total particulate concentrations) were observed for all ventilation adjustments. Overall, the training concepts developed for shipyard welders do provide control and protection from welding fume in the shipyard confined spaces.