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Why spot extraction at the source is crucial for the metal fabricator's lungs
When metal is welded, a cloud of very fine particles and gases forms—welding fume. It's often invisible in large amounts in wire welding with low fume generation, but can contain substances that over time damage airways and the nervous system. That's why controlling welding fume is a fixed part of the work environment on any metal shop, not something you only address if the fume bothers you.
The composition of welding fume depends on welding method, filler material and the material being welded. When welding ordinary steel, the fume contains, among other things, iron oxide, while alloy and stainless steel can release substances such as manganese, chromium and nickel compounds. Some of these substances are suspected of being able to cause chronic damage with prolonged exposure, and manganese is particularly known for being able to affect the nervous system with high and prolonged exposure.
The rules say that pollution should as far as possible be removed where it arises — at the source — rather than diluted in the room air: the Executive Order on work with substances and materials puts «collective protective measures at the source of the hazard, e.g. effective ventilation» before personal protective equipment (BEK 581/2026 § 17), and the cancer Executive Order requires methods that limit the formation of fume (BEK 582/2026 § 17). The Danish Working Environment Authority's old guidelines on ventilation and on welding were repealed in 2025. In welding this means local exhaust in practice, where an extraction arm or nozzle is placed close to the weld so that the fume is sucked away before it reaches the welder's breathing zone.
A large, general extraction under the ceiling can remove some smoke, but it needs to move far greater air volumes to achieve the same effect as extraction located close to the source — and in the meantime the welder himself inhales some of the smoke. Therefore point extraction is always prioritised over general ventilation where practically possible, and general ventilation is typically used as a supplement that ensures an acceptable background level throughout the room.
Where process ventilation cannot remove the pollution sufficiently — for example during welding in confined spaces, outdoors, or on materials with heavy smoke development such as galvanized or stainless steel — it is supplemented with respiratory protection, typically a welding helmet with supplied air filter or a separate fresh air system. The protective equipment is intended as the last link in a protection chain where the source is first attempted to be removed or reduced.
A filtering respirator, where you breathe through the filter yourself, may be used for no more than three hours a day and not continuously (Danish Working Environment Authority practice, VEJ 10134/2026). If there is carbon monoxide or nitrous gases in the air, you must always use an air-supplied respirator.
There is no single limit value for welding fumes. Instead, process-related limit values apply to the total fumes (e.g. 1.6 mg/m³ for MIG/MAG) and limit values apply to the individual substances in the fumes (e.g. 0.00025 mg/m³ for chromium(VI) compounds), cf. BEK 613/2026, Annex 2.
The rules only work if the equipment is present, functioning and used. It is the employer's responsibility to provide the right ventilation solutions, but it is a shared culture at the workshop that determines whether the extraction arm is actually positioned correctly every time there is welding – even when the task is urgent and even when the smoke doesn't smell particularly strong that day.