A tidy workbench in a bright community room set out with soldering irons in stands, small circuit boards and a fume extractor fan — AI-generated image, not a photograph of a real person or place.

AN INDEPENDENT COMMUNITY GUIDE

Keep your head
out of the plume.

That thin wisp from a soldering iron matters.

When rosin-based flux heats up it gives off a fume that HSE calls a top cause of occupational asthma. Community tech groups that teach soldering can borrow the same simple controls HSE describes for workplaces.

20 MINUTES of cool running water for a burn

Compare fume controls

Choose rosin-free flux
Extract the fume
Rest the iron in its stand
What HSE and NHS guidance stress

THE SHORT ANSWER

Less fume,
fewer burns.

This site is an independent guide, not health and safety or medical advice.
It is not affiliated with any church, club, group or HSE.

THE FUME

Rosin and asthma

HSE says rosin (colophony) solder flux fume is a common cause of occupational asthma, and its residues can cause skin problems such as dermatitis.

Compare controls

THE IRON

Not too hot

HSE's top tips include never overheating the iron, and its leaflet lists temperature-controlled irons among the measures that reduce fume.

Good habits

THE ROOM

Air and posture

Position the work so you can keep your head out of the fume. HSE says this plus good ventilation may be enough only for small, infrequent, rosin-free jobs.

See the numbers

A hot soldering iron resting safely in its coiled metal stand beside a pot of brass wool for cleaning the tip — AI-generated image, not a photograph of a real person or place.

HABITS FROM HSE'S TOP TIPS

Small habits
at the bench.

These come from HSE's top tips for solderers and its INDG249 leaflet. They describe good practice; a group's own risk assessment decides what it needs.

Question the flux
Ask whether rosin-based flux is needed; rosin-free and rosin-reduced fluxes exist.
Keep the iron in check
Use a temperature-controlled iron and never let it overheat.
Raise the work
Lift the workpiece so you can solder without breathing in the plume.
Extract and maintain
Use suitable fume extraction and keep it clean, following the maker's maintenance schedule.

TWO NUMBERS WORTH KNOWING

Cool the burn,
cut the lead.

One figure from NHS first aid for burns,
one from the rules on lead in electronics.

20 minutes

Time to hold a burn under cool running water

The NHS says to do this as soon as possible, within 3 hours, then cover the cooled burn loosely with cling film. Call 999 or go to A&E for burns caused by electricity, or that are large or deep.

BURNS · NHS

0.1%

Maximum concentration of lead allowed under RoHS

The restriction of hazardous substances rules limit lead, alongside cadmium, mercury and other substances, in many types of electrical and electronic equipment sold in Great Britain and Northern Ireland.

LEAD · GOV.UK RoHS

HSE says workers exposed to solder flux fume should be able to recognise early signs that their lungs or skin are reacting, and that health surveillance may be needed in workplaces.

FUME CONTROLS COMPARED

How well does it
control the fume?

HSE lists fume controls for workplaces in priority order. Pick one to see what HSE says about it. The bar shows how strongly HSE rates it at cutting exposure.

Control check

Choose a controlAvoid solderingRosin-free or rosin-reduced fluxVentilated enclosure or downdraught benchOn-tip extractionA small bench-mounted fan box

Avoid solderingFirst choice

HSE's first priority is to eliminate solder fume, for example with crimping, wire wrap or conductive adhesives, while checking any substitute's own hazards.

Rosin-free or rosin-reduced fluxSubstitute

HSE asks whether you have to use rosin flux at all: other fluxing agents are available. Check the safety data sheet of anything you switch to.

Ventilated enclosure or downdraught benchCan reach zero

HSE says a ventilated bench-top enclosure, or a downdraught bench that extracts the whole surface, is capable of reducing exposure to zero.

On-tip extractionClean it often

A nozzle on the iron captures fume where it forms and suits work that moves around, but HSE notes on-tip extraction blocks up swiftly and needs frequent cleaning.

A small bench-mounted fan boxLimited use

HSE says bench-mounted boxes are of limited use unless fitted with a HEPA filter, and that any extraction needs regular maintenance.

Sources: HSE INDG249 (rev1, 2015); HSE, Solderer (asthma) page.

Based on HSE leaflet INDG249, Controlling health risks from rosin (colophony)-based solder flux fume, and HSE's solderer page. HSE's guidance is written for employers.

Hands soldering a small green circuit board held in a clamp, with a thin wisp of fume rising beside a magnifier lamp — AI-generated image, not a photograph of a real person or place.

BURNS FIRST AID

Cool water first,
then cover.

The NHS says to treat all burns straight away: hold the burn under cool running water for 20 minutes, remove clothing or jewellery near it unless stuck, then lay cling film over it without wrapping.

It says not to put creams, oils or butter on a burn, not to use plasters, and not to burst blisters. Burns caused by electricity, or that are very large or deep, need 999 or A&E; NHS 111 can help if you are unsure.

Questions

Questions people ask

Is solder fume harmful?

HSE says rosin (colophony)-based solder flux fume is hazardous to health and a common cause of occupational asthma, and that contact with the fume and its residues can cause dermatitis.

Is the fume from lead?

HSE's leaflet is about the flux: the fume is generated from rosin-based flux during soldering. Lead is restricted separately in electronics under the RoHS rules, to a maximum concentration of 0.1 percent.

Is a small desk fan extractor enough?

HSE says bench-mounted boxes are of limited use unless fitted with a HEPA filter. Ventilated enclosures and downdraught benches can reduce exposure to zero when used properly.

What should you do if you burn yourself on an iron?

The NHS says to hold the burn under cool running water for 20 minutes, ideally straight away and within 3 hours, then cover it loosely with cling film. Electrical, large or deep burns need 999 or A&E.

Do these rules apply to a volunteer group?

HSE's guidance on solder fume is written for employers under COSHH. It is still a useful guide for groups that teach soldering, but this page is information, not health and safety advice.

Sources

Updated 19 October 2026

Keep your headout of the plume.

Less fume,fewer burns.

Rosin and asthma

Not too hot

Air and posture

Small habitsat the bench.

Question the flux

Keep the iron in check

Raise the work

Extract and maintain

Cool the burn,cut the lead.

How well does itcontrol the fume?

Cool water first,then cover.