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Med. Pr. 2001;52(6)

Occupational exposure to gases emitted in mild and stainless steel welding

Narażenie zawodowe na gazy wydzielające się w procesach spawania stali nisko- i wysokostopowych

W. Matczak, J. Gromiec

Abstract

The objective of this work was to select optimal methods for determination of toxic gases (NO_x, NO₂, CO, CO₂, O₃)and to evaluate occupational exposure of welders to those gases. The survey covered workers employed in shipyards,and other metal product fabrication plants engaged in welding mild and stainless steel by different techniques (mannual metal are, metal active gas, tungsten inert gas welding; gas, plasma, laser cutting and resistance welding). Personal and stationary air samples were collected to determine time weighted average (TWA) and short-term concentrations of gases. For determination of nitrogen oxides the following analytical techniques were amployed:spectrophotometry with collection on liquid and solid sorbents and ion chromatography with collection on solid sorbents. All the gases were determined also by automatic or direct reading methods: flow or diffusion detector tubes and photometric and electrochemical analysers. The determined TWA concentrations were below respective Maximum Allowable Concentrations (MAC) but exposure limits for short term exposure were exceeded in some cases. The average NO₂ i NO_x ratio was 1 : 4. According to Polish regulations regarding the MAC value for nitrogen oxides the analytical method should enable determination of total NO_x by either direct or indirect simultaneous determination of both NO and NO₂. The applicability of the spectrophotometric method of analysis of atmospheric NO_x to determination of low NO_x concentrations at welders working posts has been confirmed.

Key words

exposure assessment, welding gases, review of analytical methods, nitrogen oxides, ozone, carbon oxides