Hazardous Atmospheres

Oxygen deficiency is the most common atmospheric hazard, but there are many others. The atmosphere in a confined space could be corrosive, toxic, flammable, or a combination of all three.

Corrosive Atmospheres

Hydrochloric acid and ammonia are examples of chemicals that can cause an atmosphere to become corrosive. Corrosive substances are harmful to the skin and eyes, and they damage metal through chemical reaction. A corrosive atmosphere can damage soft tissue such as eyes and lungs. It can also eventually degrade equipment, creating unexpected physical hazards.

Toxic Atmospheres

Often, when working in confined spaces, entrants and attendants will encounter toxic atmospheres. These can come from cleaning supplies (like acetone), water treatments (like chlorine), or chemical storage. Others, such as carbon monoxide, can be created as a byproduct of motors or generators. Entrants and attendants need to be aware of what toxic atmospheres may be in or around the confined space in which they work. Some of these gases can cause oxygen deficiency, while others react dangerously with the body.

Flammable Atmospheres

Many gases are flammable when they come in contact with an ignition source. While the most common ignition source is an open flame, others include sparks, static electricity, welding, and soldering. Hot work such as welding is especially dangerous in spaces with a flammable or combustible atmosphere.

1926 Subpart AA require a confined space to be monitored continuously while work continues. Before these new updates to the regulations, a certified competent person only had to check atmospheric levels before entry. The new regulations recognize that hazards can arise after entry. Examples of these are a tank springing a leak, a generator introducing carbon monoxide through the opening, or limestone creating carbon dioxide through contact with acid. Your employer must provide atmospheric monitoring equipment. If an entrant or attendant notices a change in the atmosphere while work is being done in the confined space, the entrant must exit the confined space immediately.

To learn more about Confined Spaces visit our Construction Confined Spaces Online Training web page.