Handling Fumes when Using a Portable Welder

Dealing with the fumes that the welding process generates, and the shielding gases used with many types of welding (which, although not poisonous in themselves, can still displace air in a confined space and kill you quickly through suffocation), is a somewhat more problematic task when you are using a portable welder.
Obviously, if you are taking your welder to a worksite that has not been formally prepared or even purpose-built for the job of welding, then the ventilation amenities that you have fitted your own workshop out with are not going to be present. Occasionally, you will have the good fortune to work in an area with proper ventilation, such as an exhaust hood with a built in fan and a good air supply from elsewhere in the room. However, much of the time, you will find yourself either welding outdoors, or in a confined space where there are no ventilation arrangements other than the entrance door.

Using a portable welder outside is a fairly safe enterprise, from the point of view of fumes and shielding-gas asphyxiation. There is basically no chance at all of being killed by your shielding gas, since the entire atmosphere will be absorbing it and the supply of fresh air is, from a human perspective, unlimited. The very availability of air is one of the major obstacles to outdoor welding, since wind can blow away shielding gas so quickly that it has no effect on the weld and oxidation could result, damaging or ruining the weld entirely.  Clearly, suffocation is not a problem under the open sky.

Poisonous vapors can still be emitted by the welding process, however, and although these are quickly removed by the movement of the air in many cases, you should still be cautious. In particular, you should note that paint, coatings, glue, epoxies, and refrigerants all burn off with clouds of poisonous vapor, even though the toxicity varies from substances to substance. Refrigerant and solvents can even produce a mustard-gas-like vapor when heated powerfully, which can poison you through your skin as well as through the lungs. You should prepare surfaces properly to remove contaminants, wear a half-mask respirator, and try to stay upwind of the smoke plume (although this last may not always be practicable).

Working in a confined space with a portable welder and inadequate ventilation is one of the most lethal situations you can place yourself in while welding, other than perhaps cutting into sealed drums that contained wax, gasoline, or acetone. Numerous deaths have occurred over the years through the combination of welding machines and enclosed spaces.

The only way to ensure even partial safety when welding indoors without proper ventilation is to use a respirator which is fed from an air tank, so that when your local environment is depleted of oxygen you will not collapse and die, and a spotter – an individual who should also have some protective gear, and whose task is to attempt your rescue if you collapse unconscious, and who is able to carry out basic resuscitation. Never carry out indoor welding without either a good ventilation system in place, or an air supply and a spotter.