Assessment, Selection and Demonstration of Technologies and Equipment for Measuring Welder Exposure to Ozone during GMAW (MIG Welding) on Aluminum Alloys

Ozone is a by-product of arc welding on aluminum alloys and stainless steels. Assessment of exposure is difficult because emissions are short in duration and large in magnitude compared to background levels, and generally occur unpredictably during work activity. The welding environment is particularly harsh. This study applied a systematic process to identify technologies and sampling devices available in the marketplace and to select suitable candidates and reject unsuitable ones. Candidates suitable for study included colorimetric detector tubes, an Ultra-Violet (UV) air pollution analyzer, and person-portable instruments, one containing a heated semi-conductor sensor and the other an electrochemical sensor. These devices were exposed to welding plumes contained in a pre-conditioned plastic bag and to unconfined plumes during production welding (Gas Metal Arc Welding [GMAW] commonly known as Metal Inert Gas [MIG welding]) on aluminum alloys. Nitrogen dioxide is an interferent in the assessment of ozone exposure by almost all technologies. Particulates and unreacted metal atoms in the plume further complicate measurement of ozone. None of the measurement technologies overwhelmed the others in this application. The harshness of the welding environment eliminated several candidates. Colorimetric detector tubes provided the best compromise between performance and safety in proof-of-concept testing on welders.