This study was conducted to describe the exposure levels of welding fumes by the type of manufacturers, work process, welding type and the size of manufacturers, and to find out the trend of chronological changes of airborne welding fume levels. The subjects of this study were 509 manufacturers, consisting of 11 types of manufacturers, 3 work processes, 7 welding types, in Busan from January, 1997 to December, 2005. Airborne concentration of welding fume was determined by manual of National Institute for Occupational Safety and Health (NIOSH), and the data were analyzed by using SPSS 10.0 for Windows program. The mean concentration of airborne welding fume in all manufacturers was $1.29;mg/m^3$ (Range: $0.01{sim}3.00;mg/m^3)$. The level of welding fume was the highest, as $1.96;mg/m^3$, for manufactures of motor vehicles, trailers and semi-trailers, which was lower than $5.0;mg/m^3$ of 8 hr-TWA in Korean permissible exposure limit for welding fume. There was a significant difference in the mean levels of welding fumes by work process, showing the highest in welding workshop ($1.39;mg/m^3$), followed by pipeline welding workshop ($1.26;mg/m^3$) and engineering workshop ($1.20;mg/m^3$). Among welding types, the mean level of welding fume was the highest in the type of $CO_2$ & arc welding, as $1.46;mg/m^3$, followed by $CO_2$ welding ($1.40;mg/m^3$), shielded metal arc welding ($1.31;mg/m^3$), spot welding ($1.27;mg/m^3$), and so on. The highest mean level of welding fume was $1.58;mg/m^3$ in work process of pipe line welding workshop for the manufacturers of basic iron and steel, and $2.27;mg/m^3$ in the type of arc welding for the manufactures building ship and boats. By the size of manufacturers, the mean concentration of welding fume for manufactures in small scale with less than 50 workers was the highest as $1.45;mg/m^3$ (Range: $0.07{sim}3.00;mg/m^3)$. The mean level of welding fume was the highest as $1.39;mg/m^3$ both in 1997 and in 2005, showing a trend of fluctuating periodically within a range of $1.10{sim}1.39;mg/m^3$. The above results suggested that more effective control program for work environment producing welding fumes should be developed and applied since there were significant variations in welding fume levels by the type of manufacturers, work processes, welding types, the size of manufactures, and by year.