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LEV testing - metal fume fever
Metal fume fever is a flu-like illness that welders and metalworkers can get from breathing metal fume - most often the zinc oxide fume from welding or cutting galvanised steel. It's usually short-lived, but it's a clear warning of significant fume exposure, and the same fume carries far worse long-term risks. Here are its symptoms, and how to prevent it. This is general information, not clinical advice.
The short answer
Ask a welder about welding galvanised steel and many will know the feeling: flu-like symptoms the evening after, sometimes called 'the galvanised flu' or 'zinc chills'. That's metal fume fever - a real, if usually short-lived, illness from breathing metal fume. Understanding it, and preventing it, matters - both because it's unpleasant and because it's a warning of a more serious exposure. Here are the symptoms and how to prevent it. This is general information, not clinical advice. What it is. Metal fume fever is a self-limiting, flu-like illness caused by breathing metal fume. It's most commonly caused by zinc oxide fume - the fume given off when welding or cutting galvanised (zinc-coated) steel, because the heat vaporises the zinc coating, which condenses into fine zinc oxide fume. Other metal fumes can cause it too, but zinc (from galvanised steel) is the classic and commonest cause. So it's particularly associated with welding or cutting galvanised steel. The symptoms. The symptoms are flu-like, which is why it's often mistaken for a cold or flu. They include: fever, chills, muscle and joint aches, headache, nausea, tiredness, shortness of breath, and a characteristic metallic taste in the mouth. A key feature is the timing: the symptoms come on some hours after the exposure - typically about four to ten hours later, so often the evening or night after a day's welding, rather than at the time. This delay is part of why the link to the welding can be missed (the welder feels ill at home, hours after work). So it's a delayed, flu-like reaction with a distinctive metallic taste. Self-limiting, with a short-lived tolerance. Metal fume fever is self-limiting: the symptoms usually resolve on their own within a day or two, without lasting damage from the episode itself. There's also a characteristic short-lived tolerance: a welder regularly exposed can build up a resistance to the effect, which is then lost after a break from exposure - so the symptoms are worse after time off. This gives the classic pattern sometimes called 'Monday fever', where the fever hits after a weekend or holiday (when the tolerance has worn off) but eases through the week (as tolerance rebuilds). So the illness passes quickly, and regular exposure brings a tolerance that a break resets. A warning sign not to ignore. Here's the crucial point: although metal fume fever itself is usually short-lived and not permanently damaging, it's a clear warning sign of significant fume exposure. It tells you the welder is breathing a lot of fume - enough to cause the acute reaction - and that same heavy exposure carries the far worse long-term risks. Welding fume is a human carcinogen (causing lung cancer), and it also causes occupational asthma and chronic bronchitis (covered in the how-welding-fume-damages-the-lungs page). So metal fume fever should never be shrugged off as 'just feeling rough after welding galv' - it's the body flagging an exposure level that's too high, both for the fever itself and because the same exposure brings the serious harms. Treating it as normal, or as a rite of passage, misses the warning. How to prevent it. Preventing metal fume fever is the same as controlling welding fume generally - keep the fume out of the welder's lungs, following the hierarchy of control. Capture the fume at source with local exhaust ventilation (LEV) - positioned to catch the rising fume, kept working and thoroughly examined and tested regularly. Ensure good general ventilation of the workspace. And use suitable respiratory protection (RPE) where the extraction doesn't fully control the fume - which is especially important for galvanised work, because it gives off a lot of zinc fume, so the exposure is high. Reducing the exposure (better still, avoiding welding galvanised where it can be avoided, or removing the coating first where practical) prevents both the fever and the long-term harm. So the prevention is effective fume control - the same control that prevents welding fume's serious effects prevents metal fume fever too. The takeaway. So metal fume fever is a self-limiting, flu-like illness (fever, chills, aches, metallic taste) that comes on hours after breathing metal fume, most often zinc oxide from welding galvanised steel, with a short-lived tolerance that a break resets. Though usually short-lived, it's a clear warning of significant fume exposure that also carries the serious long-term risks - so it shouldn't be ignored. It's prevented by controlling the fume: LEV (kept working and tested), good ventilation, and RPE, especially for galvanised work. This is general information, not clinical advice - a medical professional advises on symptoms and treatment. This is general information.
Key points
What it is
Metal fume fever is a self-limiting, flu-like illness caused by breathing metal fume. It's most commonly caused by zinc oxide fume - the fume given off when welding or cutting galvanised (zinc-coated) steel, because the heat vaporises the zinc coating, which condenses into fine zinc oxide fume that the welder breathes. Other metal fumes can cause it too, but zinc (from galvanised steel) is the classic and commonest cause.
So metal fume fever is particularly associated with welding or cutting galvanised steel - a very common situation, since galvanised steel is widely used, and welding or cutting it releases the zinc fume. This is why so many welders have experienced it (or 'the galvanised flu'). Recognising what it is - a reaction to breathing metal fume, mainly zinc from galvanised work - is the starting point for both spotting it and preventing it. The symptoms that identify it are next. So what it is - a flu-like illness from metal fume, mainly zinc - is the definition: an acute reaction to breathing metal fume, classically zinc from galvanised steel. So it's a reaction to breathing zinc (or other metal) fume. This is general information, not clinical advice. This is general information.
The symptoms
The symptoms of metal fume fever are flu-like, which is why it's often mistaken for a cold or flu. They include: fever, chills, muscle and joint aches, headache, nausea, tiredness, shortness of breath, and a characteristic metallic taste in the mouth. So it feels much like coming down with flu, with the metallic taste as a distinctive extra clue pointing to metal fume.
A key feature is the timing: the symptoms come on some hours after the exposure - typically about four to ten hours later - so often the evening or night after a day's welding, rather than at the time of welding. This delay is important because it's part of why the link to the welding gets missed: the welder feels ill at home, hours after work, and may put it down to a bug rather than the fume. So recognising the pattern - flu-like symptoms with a metallic taste, coming on the evening after welding (especially galvanised) - is what identifies it as metal fume fever rather than a coincidental illness. So the symptoms - flu-like, hours later, with a metallic taste - are how it presents: a delayed flu-like reaction with a distinctive metallic taste. How it resolves (and the tolerance pattern) is next. So it's a delayed flu-like reaction with a metallic taste. This is general information, not clinical advice. This is general information.
Self-limiting, with a tolerance
Metal fume fever is self-limiting: the symptoms usually resolve on their own within a day or two, without lasting damage from the episode itself. So a single bout typically passes fairly quickly, which is part of why it can be dismissed as 'just feeling rough'. But its short-lived nature shouldn't be mistaken for harmlessness (covered next).
There's also a characteristic short-lived tolerance: a welder regularly exposed can build up a resistance to the effect, which is then lost after a break from exposure - so the symptoms are worse after time off. This gives the classic pattern sometimes called 'Monday fever' (or the older 'brass founders' ague' in foundry work): the fever hits after a weekend or holiday, when the tolerance has worn off, but eases through the week as tolerance rebuilds. So a welder who feels rough every Monday after galvanised work, but less so as the week goes on, is likely experiencing this tolerance pattern. This pattern is itself a clue that it's metal fume fever (from the fume exposure) rather than recurrent infections. So self-limiting, with a tolerance - passes in a day or two, worse after a break - describes its course: short-lived episodes, and a break-resettable tolerance giving the 'Monday fever' pattern. Why it still matters is next. So it passes quickly, and is worse after time off. This is general information, not clinical advice. This is general information.
A warning sign not to ignore
Here's the crucial point: although metal fume fever itself is usually short-lived and not permanently damaging, it's a clear warning sign of significant fume exposure. It tells you the welder is breathing a lot of fume - enough to cause the acute reaction - and that same heavy exposure carries the far worse long-term risks.
Welding fume is a human carcinogen (causing lung cancer), and it also causes occupational asthma and chronic bronchitis, among other harms (covered in the how-welding-fume-damages-the-lungs page). So the fume that's giving the welder metal fume fever today is the same fume that, over time, raises their cancer risk and can cause lasting lung disease. This means metal fume fever should never be shrugged off as 'just feeling rough after welding galv', or treated as a normal rite of passage - it's the body flagging an exposure level that's too high, both for the fever itself and, more seriously, because the same exposure brings the grave long-term harms. Treating the fever as normal misses the warning it carries. So a warning sign not to ignore - it flags an exposure that also brings worse harm - is why metal fume fever matters beyond the immediate illness: it signals the heavy fume exposure that also causes cancer and lung disease. Preventing it is next. So take it as a warning of dangerous fume exposure. This is general information, not clinical advice. This is general information.
How to prevent it
Preventing metal fume fever is the same as controlling welding fume generally - keep the fume out of the welder's lungs, following the hierarchy of control. Capture the fume at source with local exhaust ventilation (LEV) - positioned to catch the rising fume at the weld, kept working and thoroughly examined and tested regularly (typically at least every fourteen months). Ensure good general ventilation of the workspace. And use suitable respiratory protection (RPE) where the extraction doesn't fully control the fume.
RPE is especially important for galvanised work, because it gives off a lot of zinc fume, so the exposure is high and the extraction may not fully control it - so galvanised welding often needs RPE on top of the extraction. Reducing the exposure at source (better still, avoiding welding galvanised where it can be avoided, or removing the zinc coating from the weld area first where practical) prevents both the fever and the long-term harm. So the prevention is effective fume control - and crucially, it's the same control that prevents welding fume's serious long-term effects (the cancer, the asthma). So preventing metal fume fever isn't a separate task; it's part of controlling welding fume properly, which protects against everything the fume causes. So how to prevent it - control the fume, LEV, ventilation and RPE - is the answer: keep the fume out of the welder's lungs, with tested LEV, ventilation and RPE (especially for galvanised work). So prevent it by controlling the fume, as for all welding. This is general information, not clinical advice. This is general information.
Questions
A self-limiting, flu-like illness caused by breathing metal fume - most commonly zinc oxide fume from welding or cutting galvanised steel; symptoms (fever, chills, aches, nausea, metallic taste) come on hours after exposure and usually pass within a day or two, but it's a warning of significant fume exposure. Metal fume fever is a self-limiting, flu-like illness caused by breathing metal fume. It's most commonly caused by zinc oxide fume - the fume given off when welding or cutting galvanised (zinc-coated) steel, because the heat vaporises the zinc coating, which condenses into fine zinc oxide fume that the welder breathes. Other metal fumes can cause it too, but zinc from galvanised steel is the classic and commonest cause. Its symptoms are flu-like - fever, chills, muscle and joint aches, headache, nausea, tiredness, shortness of breath, and a characteristic metallic taste - and they come on some hours after the exposure (typically four to ten hours later, often the evening after welding), then usually resolve on their own within a day or two. So it feels much like flu, with a distinctive metallic taste and a delayed onset. Although the illness itself is usually short-lived and not permanently damaging, it's a clear warning sign of significant fume exposure - the same heavy exposure that carries welding fume's serious long-term risks (cancer, asthma, bronchitis). So it's an acute, self-limiting reaction that also flags a dangerous exposure. So a flu-like reaction to metal fume, mainly zinc. This is general information, not clinical advice. This is general information.
Flu-like ones - fever, chills, muscle and joint aches, headache, nausea, tiredness, shortness of breath - plus a characteristic metallic taste in the mouth; they typically come on four to ten hours after exposure (often the evening after welding), which can obscure the link to the fume. The symptoms of metal fume fever are flu-like, which is why it's often mistaken for a cold or flu. They include: fever, chills, muscle and joint aches, headache, nausea, tiredness, shortness of breath, and a characteristic metallic taste in the mouth. The metallic taste is a distinctive clue that points to metal fume rather than an ordinary infection. A key feature is the timing: the symptoms come on some hours after the exposure - typically about four to ten hours later - so often the evening or night after a day's welding, rather than at the time of welding. This delayed onset matters because it can obscure the link to the welding: the welder feels ill at home, hours after work, and may put it down to a bug rather than the fume. So recognising the pattern - flu-like symptoms with a metallic taste, coming on the evening after welding (especially galvanised steel) - is what identifies it as metal fume fever. There's also often a tolerance pattern (worse after a break from welding), another clue. So the symptoms are a delayed, flu-like illness with a metallic taste. So flu-like symptoms plus a metallic taste, hours later. This is general information, not clinical advice. This is general information.
Because galvanised steel has a zinc coating, and the heat of welding or cutting vaporises the zinc, which condenses into fine zinc oxide fume - and breathing that zinc oxide fume is the commonest cause of metal fume fever; galvanised work gives off a lot of zinc fume, so the exposure is high. Welding galvanised steel causes metal fume fever because of the zinc coating. Galvanised steel is steel coated with zinc (galvanising) to protect it from rust. When you weld or cut galvanised steel, the intense heat vaporises the zinc coating, and that zinc vapour condenses in the cooler air into fine zinc oxide fume - which the welder then breathes. Breathing zinc oxide fume is the commonest cause of metal fume fever, so welding or cutting galvanised steel is the classic situation that brings it on. This is a very common scenario, because galvanised steel is widely used, and welding or cutting it inevitably releases the zinc fume unless the coating is removed from the weld area first. Galvanised work tends to give off a lot of zinc fume, so the exposure can be high - which is why it commonly causes metal fume fever, and why controlling the fume (with LEV and RPE) is especially important for galvanised welding. So it's the zinc coating, vaporised by the welding heat into zinc oxide fume, that causes the fever. Removing the zinc coating from the weld area first, where practical, reduces the fume. So because welding vaporises the zinc coating into zinc oxide fume. So because the zinc coating vaporises into fume that's breathed. This is general information, not clinical advice. This is general information.
The episode itself is usually short-lived and self-limiting, but it shouldn't be dismissed - it's a clear warning of significant fume exposure, and that same heavy exposure carries welding fume's serious long-term risks (cancer, asthma, bronchitis), so it flags a dangerous exposure even though the fever passes. Metal fume fever's individual episodes are usually short-lived and self-limiting (passing within a day or two without lasting damage from the episode itself), but it should not be dismissed as unimportant just because it passes quickly - it's a serious warning, even if the fever isn't. The key point is that metal fume fever is a clear sign of significant fume exposure: it tells you the welder is breathing a lot of fume, enough to cause the acute reaction. And that same heavy exposure carries the far worse long-term risks of welding fume - which is a human carcinogen (causing lung cancer) and also causes occupational asthma and chronic bronchitis. So the fume giving the welder metal fume fever today is the same fume that, over time, raises their cancer risk and can cause lasting lung disease. This is why metal fume fever should never be shrugged off as 'just feeling rough after welding galv', or treated as a normal part of the job - it's the body flagging an exposure level that's too high, both for the fever and, more seriously, because the same exposure brings grave long-term harm. So while the fever passes, the exposure it signals is dangerous and needs controlling. So the fever passes, but it warns of a serious, harmful exposure. So it's short-lived but a warning of dangerous exposure. This is general information, not clinical advice. This is general information.
It's the pattern where a regularly-exposed welder builds up a short-lived tolerance to metal fume fever that's lost after a break - so symptoms are worse after a weekend or holiday (when tolerance has worn off) and ease through the week as it rebuilds; it's a clue that the illness is from fume exposure. The 'Monday fever' pattern refers to the characteristic short-lived tolerance that develops with metal fume fever. A welder who is regularly exposed to metal fume can build up a resistance (tolerance) to its effect - so with continued daily exposure, the symptoms lessen. But that tolerance is short-lived and is lost after a break from exposure. So after a weekend or holiday (a break from welding), the tolerance has worn off, and the welder gets metal fume fever again when they return - the fever 'hitting on Monday'. Then, as the week goes on and daily exposure continues, the tolerance rebuilds and the symptoms ease. Hence 'Monday fever': worse at the start of the week after a break, easing through the week. (In older foundry contexts it was called 'brass founders' ague'.) This pattern is itself a useful clue that the illness is metal fume fever from fume exposure, rather than recurrent infections - a welder who feels flu-like every Monday after galvanised work, but better by Friday, is likely experiencing this. It's also a reminder that the tolerance doesn't mean the exposure is harmless - the fume still carries the serious long-term risks regardless of tolerance to the acute fever. So it's the break-resettable tolerance giving worse symptoms after time off. So the worse-after-a-break tolerance pattern of the fever. This is general information, not clinical advice. This is general information.
By controlling the fume so it isn't breathed - the same as controlling welding fume generally: capture it at source with LEV (kept working and tested), ensure good ventilation, and use RPE where the extraction doesn't fully control it (especially for galvanised work, which gives off a lot of zinc fume); reducing the exposure prevents the fever and the long-term harm. Metal fume fever is prevented by controlling the fume so it isn't breathed - which is the same as controlling welding fume generally, following the hierarchy of control. Capture the fume at source with local exhaust ventilation (LEV), positioned to catch the rising fume at the weld and kept working and thoroughly examined and tested regularly (typically at least every fourteen months). Ensure good general ventilation of the workspace. And use suitable respiratory protection (RPE) where the extraction doesn't fully control the fume - which is especially important for galvanised work, because it gives off a lot of zinc fume, so the exposure is high and the extraction may not fully control it (galvanised welding often needs RPE on top of the extraction). Reducing the exposure at source - and, better still, avoiding welding galvanised where it can be avoided, or removing the zinc coating from the weld area first where practical - prevents both the fever and the long-term harm. Crucially, this is the same control that prevents welding fume's serious long-term effects (the cancer, the asthma), so preventing metal fume fever isn't a separate task - it's part of controlling welding fume properly. So keep the fume out of the welder's lungs with tested LEV, ventilation and RPE. So by controlling the fume - LEV, ventilation and RPE. This is general information. This is general information.
Metal fume fever warns of heavy welding fume exposure - the same exposure that causes cancer and lung disease - so preventing it means controlling the fume with LEV that works; we thoroughly examine and test welding fume LEV, confirming it still captures the fume, to help keep welders' exposure (and this warning sign) down. Ask us to test your LEV. This is general information.
