Evaluation on the Efficiencies of Local Exhaust Systems and Airborne Concentrations of Total Chromium, Hexa-valent Chromium and Nickel in Some Electroplating Plants

일부 영세 도금사업장의 국소배기성능과 공기중 총크롬, 6가 크롬 및 니켈농도와의 관계분석

To evaluate efficiencies of the local exhaust systems installed in chromiun and nickel eletroplating tanks, specifications of each tank and general performances of the local exhaust systems were measured in 16 electroplating plants from July 3 to November 24, 1992. Airborne concentrations of total chromium, hexa-chromium and nickel were also measured, Most of the local exhaust systems installed in electroplating plants were inadequately designed. Average capture velocities of local exhaust systems in chromium and nickel tanks were 0.45 m/sec and 0.29 m/sec. Average slot velocities in chromium and nickel tanks were 7.30 m/sec and 2.87 m/sec repectively. Both average capture and solt velocities were in noncompliance with the standards recommened by American Conference of Governmental Industrial Hygienists (ACGIH) and National Institute for Occupational Safety and Health (NIOSH), Exhausted air volume was insufficient in all local exhaust systems surveyed. Worker exposure levels to total chromium, hexa-chromium and nickel were $43.0{\mu}g/m^3$, $1.7{\mu}g/m^3$ and $9.3{\mu}g/m^3$, which were below the Korean Standard and U.S. Occupational Health and Safety Administration (OHSA) Permissible Exposure Limit(REL). However, Worker exposure level to hexa-chromium exceeded the NIOSH Recommended Exposure Limit(REL) of $1{\mu}g/m^3$. As the result of Scheffee's multiple comparions, worker exposure levels to all metals were significantly different between two groups by the management state of existing local exhaust systems (p<0.05). However, Difference between a group with local exhaust systems which were poorly managed and another group without local exhaust system was satatistically non-significant.