Occupational Safety, Environmental Protection and Occupational Medicine
Institute and Out-patient Clinic of Occupational Medicine
Working Group Inhalation Toxicology
Welding and related methods bring about the development of respirable fumes and gases. Since these substances may be detrimental to health, they have to be considered in the risk assessment of working places. To this end, measurements of the working environment are required. The results from these measurements are used for deriving appropriate protection measures which guarantee the adherence to the valid limiting values for the respective hazardous substances. The emission values which have been measured at the real working place are, in most cases, not due to individual processes during production but are values for the mixed exposition from several production processes.
The exact knowledge about the hazardous material quantities and compositions which are developing during the considered individual production process allow, besides the medical evaluation of single processes also the derivation of measures for the minimisation of toxic substances by process adaptation or adaptation of the composition of the filler materials. For this reason, welding fume examinations under laboratory conditions have been carried out besides measurement of the working environment.
Weld Fume Tests in the ISF
The ISF carries out weld fume tests in accordance with DIN EN ISO 15011 or according to customer requests for different welding processes, among others: MAG-, MIG-, TIG-, E-manual-, Plasma-, SA-, resistance spot-, laser-, laser-hybrid-welding methods, and brazing methods using customer-specific filler materials and base materials - gases, electrodes, weld wires, coatings - and, moreover, parameter- or process variations. These include:
- gravimetric determination of emission rates,
- analysis of the inorganic constituents of the fumes,
- preparation of welding fume data sheets,
- determination of the number size distribution of fume particles and particle number concentration
e.g. via FMPS, in cooperation with the Institut für Arbeitsmedizin und Sozialmedizin „IASA” or via mobile laser photometer
The execution of the tests under defined laboratory conditions allows the exact characterisation of the developing emissions of the tested individual processes.
The cooperation of the Welding and Joining Institute, ISF, with the working group “Inhalation Toxicology” of the Institute and Out-patient Clinic of Occupational Medicine, IASA, at the University Hospital Aachen allows also to carry out tests about the biological effects of the developing welding fumes.
As part of this cooperation, the “Aachen Working Environment Simulation Unit“ has been developed and is now commonly used for studies which purport the effect of hazardous substances at the working place.
The Aachen Working Environment Simulation Unit – Studies about the effects of hazardous substances at the working place
The studies which are carried out within the scope of the Aachen Working Environment Simulation Unit have the aim to comprehend and thus to prevent the development of medical conditions caused by exposition to hazardous substances in the working environment. The information gained from these data contributes to the definition of limit values in the air and in biological material.
Occupational health examinations about health hazards caused by hazardous materials are often impaired by the fact that in the real working environment often a mixed exposition of different hazardous materials is prevalent. Thus, the exact exposition conditions, individual duration and strength are difficult to determine. The Aachen Working Environment Simulation Unit allows a controlled exposition under defined conditions and can thus be used for the examination of the effects of individual emitting processes in particular welding and brazing processes on the human body.
The “Aachen Working Environment Simulation Unit“ consists of two separate areas: the emission area where the hazardous substances are produced under controlled conditions and of the exposition area where a maximum of 6 persons are tested. The two areas are connected via a controllable airing unit which allows the controlled setting and maintaining the hazardous substance concentration in the exposition area. It is thus possible to adhere to all valid workplace limit values for the tested hazardous materials e.g. welding fume, brazing fume, during all studies which are carried out in the exposition area.
In the exposition area, the mass and number concentration of the fume particles and their size distribution and also the concentration of the gases ozone, NOx and CO which are developing during welding are continuously measured and monitored.
During the exposition studies, the outer exposition and also the inner exposition of the test persons is measured via biomonitoring, chromium and nickel in blood and urine. For the determination of possible inflammatory reactions in the lungs and possible temporary pulmonary function, highly modern methods for testing the pulmonary function are applied. Besides the effects of exposition on the lungs, also the effects on the cardio-vascular system are investigated.
Up to now, several human studies about the characterisation of the biological effects of ultrafine particles from the welding fumes of different welding processes, MAG-, MIG-, E-manual, resistance spot, MIG brazing, using different filler materials and base materials, e.g. aluminium, low- and high-alloy steels, galvanized deep drawing plates, have been carried out.