Confined Space Hazards | Common Hazards In Confined Spaces

Confined Space Hazards | Common Hazards In Confined Spaces

Everyday across the country, workers enter a number of different types of confined spaces. These entries are usually meant for testing, inspections, cleaning, or repair. Specifically speaking, a confined space is any space that has a limited amount of openings for entry and exit, may produce or contain toxic air contaminants, has a high amount of concentrated inert gas, is not meant for long periods of occupancy, and could have an atmosphere that is dangerously lacking in oxygen. Any and all confined spaces MUST be tested and analyzed before entry. It should also be understood by workers the threats and hazards of the confined space. To help workers recognize these threats, we have compiled a list of the most common confined space hazards found in workplaces across the country.

Carbon Monoxide

Carbon monoxide is one of the most dangerous gases you can encounter in confined spaces due to the fact that it is virtually undetectable with human senses. It is normally produced by the exhaust of a heater or engine, and it is odorless, colorless, tasteless, and unbelievably deadly. When you breathe in carbon monoxide fumes, the gas obstructs the body’s capacity to use the oxygen that is in your lungs. Put simply, once you breathe in carbon monoxide, you can still breathe, but it is doing nothing for you. You will eventually lose consciousness and death will come quicker than you think. Make sure to always keep any machines or devices that burn fuel safely away from any confined spaces.

Carbon Dioxide

Carbon dioxide, like carbon monoxide, is also a deadly gas that is colorless and odorless. It displaces oxygen within confined spaces which leads to fatal consequences. Carbon dioxide can be created by decaying animal or vegetable matter, or by a leak springing from a fire suppression system.


Freon is a non-flammable liquid that is usually used as a solvent for flushing spaces. You can also find Freon as a gas in some refrigeration systems. Knowing this, you will want to ensure that all transfer and refrigeration systems are free of leaks. You will also want to install an alarm device in any areas that Freon will be used. These alarms will help warn workers if there is a dangerous amount of airborne Freon concentrations. Note that Freon is heavier than air, so when it is present it will cause vapors to settle on the floor. So if you hear or see the Freon alarm system go off, make sure to stand upright as quick as possible and leave the area with your head up.

confined space hazards

Hydrogen Sulfide

Hydrogen sulfide is a gas that smells like rotten eggs. However, the smell alone will not give you enough time to realize that hydrogen sulfide is present. The reason for this is because the gas will desensitize your sense of smell after only 2 whiffs, and will negate your ability to detect the odor after that. You will oftentimes find hydrogen sulfide in oil or gas drilling situations. It is usually released during the decay of organic matter that is found in sewage and mud. Like Freon, hydrogen sulfide is heavier than air, so be sure to keep your head high once you know that it is present. Other indicators that hydrogen sulfide is present is blackened copper and brass pipes or fittings.

Welding Gases

Welding gases include oxygen, argon, acetylene, and helium. These gases can leave the welding area and find their way into confined or enclosed spaces. Each of these gases have different dangers and properties, but they all enter confined spaces for the same reason, error. Sometimes, simply leaving an unused welding hose in the space can cause these gases to release and enter the area. NEVER leave a welding gas hose around, near, or in a confined space, even if it is turned off. All it takes is someone to turn the wrong valve to cause lethal gases to enter the confined area.


Luckily, ammonia will give you ample warning unlike the rest of the gases we have mentioned. More specifically, it will irritate the eyes, nose, and moist skin. If the exposure happens to occur gradually, then workers will be evacuated from the area before any injury or health concerns are raised. However, if the exposure is for an extended period of time, the respiratory tract can become extremely irritated and could possibly result in respiratory arrest or even death. If you smell ammonia, and it is strong, a leak is present. Evacuate the area and be sure to take the correct measures before reentering the confined space.

It should come as no surprise that detecting confined space hazards is a time sensitive issue due to the fact that it usually deals with a relatively small space. All it takes is a small amount of gas to enter a confined space before workers will become affected. Don’t take chances! Make sure ALL correct safety measures have been conducted before ever entering a confined spaces. Worker’s lives depend on it.

About The Author
Brett Gordon is a writer for Safety Partners, LTD.

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