Metal fume fever: symptoms, causes and prevention for welders and metalworkers

Metal fume fever is an acute illness that comes on after breathing in fume from heated metal. The HSE describes it among the acute respiratory health effects of welding fume, which it defines as effects that occur as illness quite soon after exposure. It is separate from the longer-term lung conditions that can follow years of exposure.

The name is slightly misleading because it is not an infection. The flu-like feeling is a reaction to the fume, which is why it can occur repeatedly in the same person each time they are exposed and why it is often worse after a break from work, as the HSE notes that effects are often worse at the start of the working week.

The HSE says metal fume fever is usually linked to welding or hot work on galvanised metals. It also says high exposures to mild steel weld fume can cause it. Welding fume is a mixture of fine metal particles and gases, and the HSE lists irritant gases such as ozone and nitrogen oxides among its components.

It is not limited to people who weld all day. The HSE's COSHH guidance distinguishes regular welders from sporadic welders who weld infrequently as part of another job, and expects controls for both. Cutting processes such as plasma cutting, laser cutting, flame cutting and arc-air gouging also produce fume with health effects similar to welding fume, according to the HSE.

The HSE describes flu-like symptoms that often start a few hours after exposure begins and continue for a while after exposure ends. Because "flu-like" covers a range of feelings, it is easy to mistake the illness for a cold or a virus. The pattern is the useful clue: it follows work involving fume, starts within hours and tends to be worse at the start of the working week.

Related fume effects that the HSE lists separately include dryness of the throat, coughing or tightness in the chest, which are usually short-lived and tend to be caused by irritant gases. Ozone in particular can cause this when tungsten inert gas (TIG) welding stainless steels and aluminium.

Mild symptoms that settle once exposure stops are typical, and the HSE says the illness does not usually have lasting ill effects. Even so, it is worth telling your GP or occupational health service if you have had it, because it shows that exposure controls at work are not adequate.

Breathing problems need prompt attention. The NHS poisoning advice says to call 999 or go to A&E if someone has severe difficulty breathing, loses consciousness or has a seizure after breathing in something harmful, and to call NHS 111 if you are not sure whether something you have breathed in is harmful. The NHS also says symptoms of poisoning may take a few hours or days to start.

The HSE lists other conditions that need distinguishing from metal fume fever, including occupational asthma, which involves episodes of severe shortness of breath, wheezing, coughing and chest tightness and can develop after a latency period of a few months to a few years, and acute pneumonia. It says welders are at increased risk of pneumococcal pneumonia and that a vaccination is available to reduce the risk, but is not a substitute for good exposure control.

The HSE says that if welding is part of your work activity there must be a risk assessment to identify what measures are needed to control exposure to welding fume. It sets out a prioritised approach.

• Eliminate welding where possible using cold joining such as mechanical fasteners or adhesives.

• Otherwise reduce the amount of welding, use a consumable or process that produces less fume, and make sure the metal is properly cleaned and prepared.

• Automate or mechanise the job where possible.

• Use local exhaust ventilation (LEV), which captures fume at source. The HSE describes on-torch extraction, extracted benches and booths, and movable LEV hoods.

• Where welding is only occasional (less than once a week and lasting less than 1 hour), the HSE says respiratory protective equipment (RPE) and good general ventilation should be provided, and that you must also protect others nearby.

Individual attacks usually resolve. The more important issue is repeated overexposure, because the same fume also carries longer-term risks. The HSE says the International Agency for Research on Cancer concluded that all welding fume can cause lung cancer and may cause kidney cancer, and that exposure to welding fume may contribute to a decline in lung function and to COPD, although it says the evidence for COPD is not enough to prove a definitive link.

If you think your work is making you ill, raise it with your employer, safety representative or occupational health service. Under COSHH, employers are expected to assess and control exposure. NHS care is the same whether the cause is occupational or not; a GP can examine you and record the work link in your notes.