Atmospheric Hazards in Confined Spaces

Statistically, atmospheric hazards are the most common cause of death in confined space accidents.?It is important that individuals who work in or around confined spaces understand these atmospheric hazards.?We generally separate the different types of atmospheric hazards into oxygen-related hazards, flammable or explosive hazards, and toxic hazards.?In this post, we will take a quick look at each one.

Oxygen-Related Hazards

Oxygen is essential to sustain human life.?All our vital organs rely on oxygen to properly function.?The air you are breathing right now is comprised of approximately 20.9% oxygen.?If the oxygen levels are below that, you can begin to experience health effects.?In confined spaces, we use the range of 19.5% – 22% to define an acceptable oxygen concentration in the air.?However, any oxygen concentration above or below 20.9% could indicate there is another hazard present.

Oxygen deficient atmospheres (<19.5%) can be caused several ways.?The oxygen can be displaced by another gas, or consumed by combustion, oxidation, or even a worker’s respiratory system.?On the flip side, oxygen enriched atmospheres (>22%) can occur when pipes or cylinders leak, liquefied gasses are improperly handled or disposed, and through mad-made processes such as welding.

Flammable or Explosive Atmospheres

An atmosphere is explosive when a flammable gas is present in the space in enough quantity that it can explode with the introduction of an ignition source.?If there is not enough of the flammable gas, we refer to the gas as being below its lower explosive limit (LEL).?If there is too much flammable gas, we refer to the gas as being above its upper explosive limit (UEL).?It is the area between the LEL and UEL that is the most dangerous – the explosive range.

Gases are not the only explosive hazard inside confined spaces.?Combustible dust explosions occur when a fine, combustible dust is suspended in the air and ignited.?Between 1980 and 2005, there were 281 combustible dust incidents that resulted in 119 workers killed and 718 injured.

Toxic Atmospheres

Depending on the type of space, confined spaces can have a wide variety of toxic gases present in them.?The two toxic gases frequently encountered in confined spaces are carbon monoxide (CO) and hydrogen sulfide (H2S).?They share some similarities, as well several crucial differences.?They are both toxic at low levels, and flammable at higher levels inside of a confined space.?Additionally, they are both colorless.

They differ in other ways.?Notably, H2S has an odor of rotten eggs.?It is also heavier than air, so it will settle at the bottom of confined spaces.?CO is lighter than air and is completely odorless.?Individuals performing confined space entry must understand these characteristics to properly monitor the space prior to and during entry operations.

Remember, air monitoring should be performed prior to entering and continuously while individuals are working in confined spaces! Visit our web site at www.ElderTechnicalRescue.com to learn about some of the training programs we provide related to air monitoring and confined space entry.

Stay safe out there.