It is extremely important when welding to consider the type and size of the room that you will be in. Because the process of welding produces a high number of contaminants in the air, if a room is not properly ventilated, there is a high likelihood that the welder or bystanders will inhale toxins. Whether or not a room is properly ventilated depends on a number of factors. The first is the size and the layout of the space where the welding occurs. Next, you have to consider the number of people involved and the types of work that they're all doing. Additionally, you want to consider the natural airflow, whether there are any windows or fans, or other types of natural air circulation. Finally, you want to consider where the workers stand in relation to where the toxins are being produced.

There are two basic ways to provide a well ventilated area. The first, is a process called natural ventilation. Natural ventilation simply means that you find a large unrestricted space that meets general safety requirements for the type of work you be doing. Normally you'll want to space that's in excess of 11,000 ft.² per welder, ceilings that are vaulted above 17 feet, and the ability for air to flow between the different areas. If you cannot meet these minimum specifications, you will likely need to use the second method, mechanical ventilation.

Again there are two types of mechanical ventilation. The first type, is known as "low vacuum." These systems consist of having a hood above the working area acting as a vacuum to suck out the air. Nearby, there is a fan that brings in fresh air from the outside. Together the fan in the hood work to continually circulate air. Removing the bad air through the hood and bringing in fresh air through the fan. Such a system however, still requires a decent amount of space.

If you're pressed for space, you may want to look into what is known as a "high vacuum system." These systems consist of a high-powered vacuum placed directly next to where the welding is happening. As such, the goal is to quickly remove all the toxins before they can disseminate into the greater airflow. The toxins are trapped in HEPA filters and immediately the air is recirculated.

Because of the variety of work that welders engage in and the numerous types of materials they use, it is very difficult to list all the possible toxins that might be created. Therefore OSHA recommends that air samples be taken on a continuous basis so that the ventilation can be adjusted accordingly.