THE EFFECTIVENESS OF VENTILATION SYSTEMS IN REMOVAL OF AIRBORNE CONTAMINANTS PRODUCED BY ARC WELDING IN SELECTED MISSOURI VOCATIONAL AGRICULTURE MECHANICS LABORATORIES

It is estimated that sixty percent of all secondary programs offer vocational education programs, some which may create potential health hazards. The literature has indicated that breathing dust and gases produced by arc welding may cause health problems. Health hazards to teacher, students or visitors in vocational agriculture mechanics laboratories can be minimized by proper ventilation.;Research questions were: (1) What are the types of ventilation systems used in vocational agriculture mechanics laboratories in Missouri? (2)Do the ventilation systems used in vocational agriculture mechanics laboratories meet or exceed OSHA ventilation standards? (3)Which ventilation system is most effective in removal of airborne contaminants produced by arc welding in vocational agriculture mechanics laboratories? (4)How effective is the welding helmet in diffusing fumes and gases from the breathing zone of the welder? (5)What is the level of teacher exposure to fumes while teaching and supervising as compared to student exposure to fumes while welding? (6) Does the height of the boot pickup change the amount of fumes and gases present in the environment of vocational agriculture mechanics laboratories?;Procedures. The population for the study included vocational agriculture mechanics laboratories in Missouri which have fans (wall and ceiling), drop curtains, hoods, boot pickups and precipitators as ventilation systems. The sample consisted of five randomly chosen schools per ventilation system.;Six students from each school welded constantly for one hour in order to produce measurable welding fumes and gases. Measurements of iron oxide, carbon monoxide and ozone were taken and compared to OSHA standards in order to determine which ventilation system was most effective in removing airborne contaminants produced by arc welding. Two students, the teacher and the area were monitored with air sampling equipment which collected iron oxide. Carbon monoxide and ozone were collected with hand-type pumps and detector tubes.;Purpose of the Study. The purpose of this study was to analyze the effectiveness of ventilation systems in removing airborne contaminants produced by arc welding in vocational agriculture mechanics laboratories.;During the collection of data, each ventilation system was in normal operation. The dimensions of the facility and ventilation at each school were measured and recorded in order to determine if the ventilation system met the OSHA ventilation standard for air flow.;This study tested three research questions and five hypotheses. The design for this study included descriptive, comparative and experimental procedures.;Conclusions. Based on the results of this study, it was concluded that: (1)Fans, drop curtains, hoods, boot pickup above the table and precipitators did not meet OSHA ventilation standards for air flow in cubic feet per minute, (2)Iron oxide exceeded OSHA standards in vocational agriculture mechanics laboratories, (3)Carbon monoxide was well under the OSHA standard in all schools, (4)Ozone was an airborne contaminant which exceeded the OSHA standard in two out of four ventilation systems, (5)In this study the helmet did not diffuse iron oxide away from the breathing zone in four out of five ventilation systems, (6)The student's level of exposure to iron oxide was higher than the teacher's level of exposure when fans, drop curtains and precipitators were used as ventilation systems for one hour, (7)The boot pickup on the table was more effective than the boot pickup above the table in removing iron oxide and carbon monoxide from the laboratory environment. However, the boot pickup above the table was more effective than the boot pickup on the table in removing ozone from the laboratory environment.