Atmospheric Hazards

Oxygen Deficient Environment

The air we breathe contains 21% oxygen. An oxygen deficient atmosphere contains less than 19.5% oxygen. Oxygen deficiency, or lack of oxygen, can cause fatigue, loss of consciousness, and even death. Oxygen deficiency in a confined space may be due to nitrogen intrusion, welding, grinding, oxidation, coating, or carbon dioxide buildup after a vacuum test. The minimum level for normal breathing is a 19.5% oxygen concentration level. Below this level, an environment is considered hazardous.

Oxygen Enriched Environment

Oxygen enriched air is defined as air that contains more than 23.5% oxygen, which can increase the likelihood of ignition. Although oxygen is not flammable on its own, when combined with a combustible material (vapors, gases, and even dust), it can become flammable.

While oxygen deficiency is the most common atmospheric hazard, 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.

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.

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.

To learn more about HAZWOPER visit our HAZWOPER 40 Hour Online Training web page.