The dangers of smithing and other metalworking do make an appearance in late medieval literature from western Europe, although perhaps not quite as we might imagine.

First, there are a few cases in civic and ecclesiastical records where a person is noted as requesting remission from duty or payment for accidents involving what OP suggested as a risk: splashes or shards of metal. A priest in fifteenth-century Germany, for example, lost most of the vision in one eye from a splash of lead in a soldering accident. (It's possible that this priest had a second career, evidently involving metalworking. This was not uncommon for parish priests in the late Middle Ages whose ecclesiastical position paid poorly). Other tasks involving splinters and debris are noted for causing similar accidents, such as woodworking and tree-trimming. This seems to suggest a lack of eye protection in that respect--which is backed up by woodcuts and illuminations of medieval forges, although it's impossible to know how "standardized" those depictions are versus reflecting real practice. Smiths are generally pictures wearing aprons, but whether that is a sign that they wanted to protect their clothes or an iconographic marker of artisan status is an open question.

Second, statutes of blacksmith and goldsmith guilds (along with other craft guilds) frequently establish provisions not just for charitable work in the community, but for caring for old and sick members of the guild--especially those injured on the job. The goldsmiths' guild of Parish, for example, collected the profits from when its members were caught working (illicitly) on Sundays to help fund this.

The primary places where the hazards of metalworking are discussed, however, are late medieval medical and trade handbooks. Although what is usually called "the first work of occupational health" dates from 1473 (published in 1520 in Augsburg; PDF here), there are earlier references in more systematic medical treatises as well.

The dangers of metalworking, to medieval people, fell into two basic camps as they saw it: lung trouble from poisonous smoke and dust, and eye trouble from smoke and heat. Discussions of problems are vastly more frequent than solutions, especially concerning declining vision. In fact, one might consider the frequency of connections between blindness and metalworking scattered throughout sources from west and east to be a sign that eye protection was lacking. Notably, however, the danger is linked to long-term exposure to heat and smoke (including perpetually watery eyes) rather than industrial accidents with metal.

Ulrich Ellenbog in the pamphlet mentioned above, however, has a few suggestions for guarding oneself against the "poisonous evil vapors and fumes" over the long term. Now, Ellenbog was also very interested in learned alchemy, and this plays a prominent role in his treatise. That gives rise to the question of just how much of his work is prescriptive, an academic writing out of old books, and how much is descriptive, broadcasting current practices to others. Or is Ellenbog simply supplying an alchemical/humoral ("medical") background to existing safety precautions? It's noteworthy that his primary audience was goldsmiths, a prestigious craft whose participants would likely have had at least some formal education.

Ellenbog observes that it is bad to burn damp coal, and it is worse to burn coal in a closed room. So open the windows--yes, even in winter. It's also not a good idea for masters to make their apprentices sleep in the same room as the forge. Get them good clean air.

It's not just the coal fire that's the problem, though. Melting metal also release noxious fumes. Diving into alchemy, he raises the point that smoke from a burning metal takes on the characteristics of the same metal, only amplified. Some metals and therefore their smoke is cold and damp. This seems paradoxical to us when we think of melting metal and smoke, but it relates to the internal effect. Ellenbog describes a chilling and stiffening of limbs and organs--imagine the sensation of having gunk in your lungs so that you can't breathe, you can't get the gunk out.

His first set of advice here falls in line with dealing with coal vapors: avoidance. Don't lean over the burning metal! This might have had a side effect of helping protect one's eyes from the smoke, but that's not his point: he suggest placing a piece of fabric against your mouth ("kissing it") to act as a mask to make extra sure you're not breathing it in. I've never seen a breathing-mask pictured in a woodcut, but that could mean either that it was not a common practice or that it did not suit medieval iconographic standards to cover up the mouth in this case. (I'd wager the former, but that's speculation.)

Drawing on medieval disease theory that blamed "bad air" for illness and advised fighting it with air that smelled good, Ellenbog offers various suggestions for potpourri concoctions to balance out the bad air with good. He also recommends holding various items in one's mouth, items that range from berries to herbs to emeralds. It's, again, a standard medieval view of "spices" (which Paul Freedman defines as "something rare and probably from the East" in the medieval imagination) as remedies rather than flavorings.

And if all that doesn't work and the smoke is just too much for you, Ellenbog finishes, eat a bunch of garlic and drink a bunch of wine.

As a follow up, were trade skill workers aware of some other dangers of this type of work, such hearing damage from loud noises, or respiratory damage from inhaling wood dust?

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