TWI Industrial Member Report Summary 549/1996
P C J Anderson and R Wiktorowicz
The mandatory limits for exposure to ozone are, in some circumstances, exceeded during arc welding. This report outlines how the ozone level during welding can be measured, and reviews the measures which can reduce ozone exposure of welding personnel.
Ozone is produced when ultraviolet radiation from the welding arc interacts with oxygen. The UK Occupational Exposure Standard (OES) for ozone, specified in the Health and Safety Executive Document EH40/95: 'Occupational exposure limits 1995', is 0.1 ppm for an 8hr time weighted average (TWA) reference period, and 0.3 ppm for a 15 min TWA reference period. The 0.3 ppm limit cannot be exceeded more than four times a day. Several studies have demonstrated that, under certain conditions, gas-shielded arc welding may give rise to ozone levels which exceed the permitted limits.
- To identify the factors in arc welding processes which may affect the ozone concentration in the workplace.
- To identify the practical measures which can be taken to limit the exposure of welding personnel to ozone during gas- shielded arc welding.