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A few weeks back I was being a moron and decided to solder something with lead-free solder. I didn't have any experience soldering so I assumed lead-free solder was harmless, and I breathed in loads of lead free solder fumes. I soldered like this for around two days around two hours each day. Should I be worried?

ocrdu
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Scam Likely
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    Remember: these fumes aren't good for you, but neither is *water* if you drink too much of it. It's all about the dose. The dose you got in a few hours of soldering is far too small to have any detrimental health effects at all. – Hearth Aug 18 '22 at 01:14
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    I breatehd these al my lief adn tehre's nothin wrogn with me. – a concerned citizen Aug 18 '22 at 06:17
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    Having any breathing difficulties you didn't before? No? You'll be OK. But really man, there's visible smoke pouring out of the solder as you go - No smoke is healthy to be breathing in so why would you do that to begin with? Next time, put a small fan next to the table to blow the smoke out of your face and open a couple windows for ventilation. – Kyle B Aug 18 '22 at 06:31
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    @Hearth I see what you are trying to say, but I want to remark that the comparison is potentially misleading for non-experts. You are correct in principle, but toxicity level of solder fumes is order of magnitudes higher than water's. That is, the OP is most probably ok, but they should not get the impression that breathing that level of fumes every day for, say, months or years is absolutely safe. – LorenzoDonati4Ukraine-OnStrike Aug 18 '22 at 08:54
  • The vaporized flux is the concern. It might cause a sore throat and ultimately allergies. At one point I soldered for two weeks straight, 8+ hours a day, without a proper fume extractor, feeling sore in the throat afterwards. Definitely not healthy. Pretty much every professional soldering veteran I know, who've worked with soldering all their life, has some manner of problem with allergies or asthma/their lungs etc. Using a professional fume extractor is the only viable solution in the long run, don't rely on crap like fans or "holding your breath". – Lundin Aug 18 '22 at 13:21
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    To get a sense of perspective, how often have you walked next to a busy road in the last week or so? That would have exposed you to air pollution from car exhausts. You can equate what you breathed in during soldering to a few hours walking next to a busy road, and most people don't worry about that sort of exposure unless they live on said road. – Crazymoomin Aug 18 '22 at 14:43
  • Yes, to be perfectly clear I agree completely with @LorenzoDonatisupportUkraine--the fumes from flux are a *lot* worse for you than water. Think of it as somewhat worse than car exhaust--something to be avoided, for sure, but a little exposure isn't going to kill you. Do get yourself a fume extractor and/or at least wear some kind of respirator or mask while soldering. – Hearth Aug 18 '22 at 15:53

4 Answers4

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Should I be worried?

Not really. In any case, the deed is done, so worrying won't retroactively fix anything. There's no "therapy" that would undo the exposure, since the exposure itself is so minuscule that it'd be hard to even quantitatively determine it just by taking samples from your body.

But, first of all: presence of lead in the solder is beside the point as far as fumes go in point soldering. Lead is important only in direct contact, i.e. you should wash your hands periodically while and after handling leaded solder. Don't lick tin-lead plated wire or component leads mindlessly, and don't lick your fingers while soldering. That's all there's lead-wise.

The fumes you're breathing during point-to-point/component lead soldering contain only trace amounts of the solder alloy. There would be way more of them - enough to be a concern - if you were hovering above a continuously-on solder pot, or worse yet - with an air leak from a wave soldering bath - but you're not doing that.

In hand-soldering, most of the fumes come from the flux. The flux fumes are comparable to various smoking/vaping products, except in much lower concentration, and should not be a problem in occasional use. If you want to keep the hobby, get a little fan to blow the fumes away, and work in a ventilated area.

If the area you're in is not ventilated well, use a whole-room air cleaner in addition to the fan. It will catch particulates from the flux, and adsorb the vapors. Make sure the air cleaner has both HEPA and carbon adsorber elements.

Solder "fume extractors" are a bit of a pointless thing if they don't provide serious air filtration or are not vented to outside. Any "extractor" that you can buy for a couple hundred bucks is not worth the the paper that comes with it as a "manual".

For occupational manual soldering on a production floor, the fumes are vented to outside, just as is the case in a welding booth, etc.

An aside: humans can actually get rid of small amounts of excess lead. The minuscule lead absorption in hobbyist leaded-solder circuit soldering is a couple orders of magnitude below our ability to shed lead. But now a kicker: The only way you can get rid of excess iron is by bleeding... No joke.

Kuba hasn't forgotten Monica
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Back in the ‘80s OSHA showed up one day at the factory where I worked. An employee was convinced that they were being poisoned by all the soldering, they complained to OSHA and OSHA decided to do an in-depth study over several days.

We had about 40 people hand-soldering for 8 hours per day using a combination of non-regulated soldering irons with lead-tin rosin core solder and temperature regulated solder pots with lead-tin solder and dippable liquid rosin-type flux.

There were no fume extractors and no special ventilation, just a 10% fresh air intake on our heating system. By the end of each work day there was a noticeable haze in the room from all the soldering. The factory had been operating that way in this location for about 10 years.

OSHA equipped six employees with wearable air pumps that took air samples every minute from a sampling tube attached to the employee’s shoulder. They wore these pumps all day for three days. OSHA also took swab samples from various surfaces.

The results? No lead and no tin or other metals in the air samples. Trace levels of aldehydes and ketones in the air samples, probably from the smoke created by rosin and flux, but far below OSHA’s PEL and not actionable. There were traces of lead in the floor dust behind a water cooler but none on the water cooler itself or on any other surface except workbenches near solder pots where dross had been skimmed off.

There were no solder-related mandates from OSHA following the inspection, but a recommendation to improve ventilation. The company installed fume extractors for all soldering stations, which cleared the air. Dry-sweeping the floor was prohibited in the factory in favor of HEPA vacuuming and wet mopping. Eating at workbenches was already prohibited, and there were already signs to wash hands before eating, smoking or applying cosmetics.

Going beyond OSHA recommendations, the company also offered blood tests for lead to any employee who wanted one, and about a dozen people volunteered. Most had been soldering daily for 10-15 years, but one, a new employee with us just a couple of months and not using solder at all in her job, was pregnant and wanted to be tested just to be sure. No lead was detected in any employee’s blood except that new employee. Just before taking the job, she had spent the last year renovating an old house and was probably exposed to lead paint dust.

I realize you asked about lead-free solder. The correct answer to your “worry” question? Based on real-world experience backed up by laboratory measurements: Forget about it!

MTA
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All of the answers above are valid, but they overcomplicate the issue massively. Given you're clearly worried, I'll spell it out for you.

No, you should not be worried. You won't have done any harm to yourself. This would be true even with leaded solder.

Any health-effects that may or may not arise from solder fumes are only going to arise after significant amounts of exposure over many years.

ScottishTapWater
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In addition to @Kuba answer:

There is a variety of fluxes used in tin-based (be it lead or lead-free) soldering.

If you are soldering electronics, chances are you are using rosin/colophony flux (separately or as an ingredient of the solder). Its fumes are perfectly safe.

On the other hand, soldering other things (e.g. iron based alloys) usually requires other fluxes, including hydrochloric or phosphoric acid. Safe these are not, but they have quite unpleasant smell so most people instinctively avoid harmful exposure.

fraxinus
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    Whilst I agree with your "perfectly safe" for this short-term exposure, it's worth mentioning that colophony has been shown to cause (after long-term exposure) occupational asthma, and exposure to it is regulated (at least in the EU) – SiHa Aug 18 '22 at 13:58