[BR3W CITY]

Since this is a rather obscure topic to those who haven't done much shop-situation welding, I wanna keep this discussion going for a moment.

Like many of the home-builder, brake or carb cleaner is usually grabbed as the defacto solvent...sometimes you don't even think the part will be welded or heated, but it happens. I have asthma, and bone cancer....so I became hyper aware of this stuff as my doctors had panic attacks when I would tell them the type of chemicals I was semi-routinely exposed to. However, it actually resulted in THEM becoming more aware of what those of us in the hobby sometimes see (keep in mind, we are a small % of the population, and many don't even think to include the fact that they are a hobbyist when discussion certain topics with medical professionals).

After having access to a large Lincoln-sponsored welding test lab, I got to see some REALLY common sense ways of tackling these problems. They might seem common sense to a production welder, but for a hobbyist, probably not.

1. Acetone. Its kept around for aluminum welding, but in general is an excellent solvent so long as you're aware of what its being used on. Its fairly cheap in bulk to keep in a a squirt bottle or (certain compatible) spray bottles properly labeled. Won't break the bank like cases of brake cleaner, and its evaporation doesn't leave harmful residue.
Cost: $

2. Positive pressure in the working environment. While direct fans can force shielding gasses around or blow out your torch, having a large exhaust fan or a roof/wall inlet fan can help keep shop pressure just slightly above 1 bar. This will prevent harmful gasses from clouding, settling, or condensing.
Cost: $-$$ depending on how far you take it

3. Workstation filtration aka the fart-sucker. Despite the name, most of you have probably seen something like this. They are high-volume low-pressure air systems which resemble a dust collector from your highschool shop class. Designed to suck up gaseous fumes, filter the air, and bleed it back into the room or into a vent stack. You can make one yourself for under $150, or even use a shop-vac (if your welding unshielded).
Cost: $$-$$$$

4. Personal respiration protection. This is tricky for welding. See a dust mask works for grinding but not painting, and a respirator works for painting but won't fit under a welding helmet...let alone comfortably. The only real option is a sealed, filtered welding system. These are now commonplace in production facilities who weld medical process pipe or dairy piping, due to the release of hexavalent chromium when welding certain grades of stainless. The cheapest type is like a welding helmet with a neck piece and gask-mask ports on it, however they are not as common, and really awkward. The other is also a sealed helmet (looks like a diving helmet), which connects to a waistpack or backpack, or in rare cases a centralized air system. These work very well, but are VERY bulky, and well out of reach for most home welders.
Cost: $$$-$$$$$$$$$$$$$

Longwinded, but hopefully it gives you guys a better idea of what the "bigs" do when exposed to potential toxic gas exposure. You don't have to do any of it, but sometimes even the basic concepts can be applied in more budget conscious or clever way. Just remember, don't use anything made of synthetic materials (that aren't fire cert.), and do NOT use any form of external air supply that relies on compressed 02...that will make you a bomb.