Oxygen-Deficient Levels & Dangers in a Confined Atmosphere

Does your job require working in small spaces? Are you worried about the regulations concerning such kind of work? You could be a part of an oxygen-deficient atmosphere. In this article, find out all the levels and dangers of a confined space and keep yourself safe.


Oxygen-deficient levels start as soon as the oxygen drops below 19.5%. Asphyxiation is the most immediate danger in a confined atmosphere once the oxygen content starts dropping.

What are oxygen-deficient levels & dangers of a confined space?

The minimum O2 required is the same as in any other space. Any place with less than 19.5% is considered an oxygen-deficient level in a confined space and has certain dangers. Anything less is hazardous to the workers or the inhabitants of the space. Asphyxiation can be a common occurrence in small areas with less breathing ability and is a serious danger. It may start as a small feeling of dizziness or confusion. Still, eventually, as the oximeter reading drops, you can start to feel:

  • tired
  • nauseous
  • and even faint.

The final blow is when the oximeter reads 88mm Hg. At this point, you need a medical professional. Below 60mm Hg, it’s advised to get the supplemental tank hooked up with a mask.

boost oxygen canister

Where can it occur?

Manufacturing sites, storage units, electric vaults, underground tanks, and pipelines are essential to keeping our goods and water supply, safe and accessible. That, too, all year round! Many people take for granted the huge workforce it takes to build, equip and maintain such confined spaces. Unfortunately, this workforce exposes itself to the risk of oxygen deficiency, which can affect one’s health. These workers already risk their lives by exposing themselves to dangerous:

  • chemicals
  • electrical tunnels
  • pits
  • and manholes.

Though working in such spaces will remain somewhat dangerous, the least we can do is ensure that this spacing goes through as less oxygen deficiency as possible. And a couple of things can be done to monitor the risk of oxygen deficiency in these areas. Take a look at all the terminology you need to know below.

What is oxygen deficiency?

20.9% of the atmosphere we live and breathe is made of oxygen. The remaining is mainly comprised of nitrogen. When this percentage drops even minutely, to 19.5%, for example, the atmosphere becomes O2 deficient. AT 16% concentration, the symptoms get even worse, and the individual starts to feel tired, drowsy, and may even faint. Below 10% concentration, the fainting can even be fatal if supplementary O2 is not supplied immediately.

What is a confined space?

A confined space can be one that, although it may have enough space to perform a few tasks, one cannot stay there for a longer duration. It may only accommodate one to two people and may not even have a proper entry or exit point. Due to the smallness of the space, the oxygen supply is low. It can only sustain individuals for a couple of minutes or hours. Most accidents and health hazards posed in confined spaces occur due to asphyxiation due to low O2 and nitrogen or carbon dioxide concentration. The second common health hazard is toxic gases or fumes in the space that can even prove fatal.

What are safe oxygen levels?

The Occupational Safety and Health Administration sets the standards of appropriate O2 in workplaces, especially confined spaces. The regulation for oxygen concentration is between 19.5% and 23.5% of the total atmosphere.

Anything in excess or under is considered dangerous. While low concentration can harm the human body, excess levels can cause fire hazards or even an explosion. Such a phenomenon is called oxygen enrichment.

What is considered deficiency?

Below 19.5% concentration in the environment is considered a deficient environment. Suppose it leads the individuals to struggle to breathe and have pulse oximeter readings below 88. In that case, they should be rushed to a medical facility immediately. Anything below 60 mm Hg in oximeter readings will require supplemental oxygen.

What are the risks of deficiency?

The body’s transport system through the blood starts to fail once the oxygen drops. It starts to cause symptoms like:

  • giddiness
  • confusion
  • weakness
  • fatigue
  • fainting
  • lack of coordination
  • and trouble breathing.

The longer the oxygen deficiency persists, the more danger it poses for the heart and brain. Hypoxia will cause the brain cells to start dying at their worst. If this continues, the results are death. The causes can be the environment but also histories of previous diseases or ailments like:

  • pneumonia
  • sleep apnea
  • bronchitis
  • and other heart problems.

What is oxygen enrichment?

Enrichment refers to the occurrence of too much O2 in the environment. Although it sounds safe, it can be extremely hazardous. How, you ask? Well, O2 is what enables the fire to be lit. Even though you think there aren’t many flammable objects around, plenty in your house can trigger an explosion during enrichment levels. The flick of a cigarette lighter, the stove, a candle burning in the bathroom, and much more. These seemingly harmless items can become very flammable when too much fuel is in the air. It can lead to an explosion as well.

Oxygen-enriched atmosphere hazards

When the environment has gases or liquids with an O2 concentration of more than 21%, you are looking at a case of enrichment. When you have so much O2 in the air, it can trigger even the littlest of sparks, which would normally be harmless, to be harmful. Eventually, the risks include fire, explosion, and ignition due to increased temperatures and flammability.

Detection sensors

Oxygen analyzers are a neat tool to see how much the environment is appropriate for your living. Let’s take a look at the best ones.


Amazon’s choice for the analyzer in the market. It has an LCD screen to show you the right percentage of concentration in the air. It has an inbuilt alarm system for high or low concentration alerts you immediately. It runs on battery and is super portable and lightweight for use on several work sites.

As we tested out Maxtec, we found it was easy to use.


  • Maxtec will last a long time.


  • It’s not the cheapest measurement device.
  • Make sure you know it’s to check scuba tanks and more.
Maxtec is a popular brand.

Forensic Detectors

Here is a superb ultrasonic detector with a rechargeable lithium battery and super portable for high convenience. The battery lasts for approximately 24 hours and even has a wall plug charger for fast charging. You can buy it stress-free since the high-quality product has a 1-year limited warranty.

We tested out the Forensic Detector, and it worked great at home.

Battery24 hours
Made inUSA


  • Worked as advertised.
  • Great price
  • Well-built


  • None
Make sure you see the range it tests.

XLA alert

A neat little tool that can detect up to four atmospheric gases. The high-definition wide LCD screen shows the Carbon monoxide, O2, combustible gas, and Hydrogen sulfide concentration in the air. The item weight is only 200 grams for easy mobility. It’s also password protected, so only you have access. Tested for waterproof, explosion proof and dust-proof properties, it’s unlikely ever to let you down. It has an alarm and human voice audio that keeps you updated on the numbers. 100% satisfaction is guaranteed with the 1-year warranty. It’s also rated highly for ease of use and value for money, so buy without any worries!

NameXLA Alert
BatteryDC3.7V Li-on battery, 1800mAh
Item Weight‎10.6 ounces
Product Dimensions‎5.5 x 2.9 x 1.3 inches


  • Cheap small device
  • Good value


  • It doesn’t feel as well built.
  • The description could be better.
XLA Alert
Here's a good budget unit.


Another highly impressive detector with 4 parameters. Detect the O2, CO, H2S, and LEL (combustible gases) right away. It is tested for durability as the company realized it’s what most detectors lack the most. You can place it on your belt clip for easy carrying around while at work. The sensor’s service life is up to 24 months, after which you will need to replace it easily. It shows the concentration in PPM or percentage levels.


  • Good price


  • Only 2 years of life on it.
  • A bit loud
Here's another good budget option.

What is the maximum concentration for breathing?

The ideal rate of O2 in the air is 19.5-21%. Anything above 23.5% is considered enriched air. It would be the maximum concentration suitable for OSHA. Humans can survive with 100% concentrated air, too. Still, the environment will likely catch fire with so much fuel, and the results would be life-threatening. To answer the question, anything above 19.5% can be survived and suited for breathing but above 23.5% will prove disastrous due to external factors.

High altitudes

High altitude sickness is a common ailment that occurs when flying. Some people experience ear blocking, nausea, and in-flight sickness. The same can be said for mountains if you are hiking very high up where the O2 drops, like Everest expeditions. Those with sickle cell disease or sickle cell traits are at higher risk of such sickness. Lung diseases like COPD, sleep apnea, cystic fibrosis, and pneumonia can affect your travel, so it’s best to check with a medical professional beforehand.

As you can often see in Marvel movies, anything above 10000 feet requires supplemental oxygen. This can be in the form of oxygen masks or built features like in the Iron Man suit. Without sufficient air to breathe, you will suffer hypoxia, dizziness, confusion, fatigue, and loss of consciousness. The final result without supplemental O2 is death.

Nowadays, you can find many portable oxygen cylinders:


Here are 4 lightweight, portable cans with 95% pure oxygen. It is ideal for athletes who are out of breath soon. Increase your focus and mental clarity with this first thing in the morning. No need for coffee- just pure, sugar and caffeine-free breathing fuel!

Size5 liter
# of canisters4
Total volume20 liter


  • They work great.
  • Near-perfect reviews.
  • Great seller


  • It gets expensive to use.
Get a quick boost.


Pure recreational cans for those who want to energize themselves. 99.7% pure natural oxygen to your brain, so you never run out of breath. 50 breaths of highly-rated breathing fuel to maximize your performance day after day. Blast yourself with a power-packed punch today!

NameO2 Blast
Size4 Liter
# of canisters3
Total volume12 liter


  • Great against headaches


  • Expensive to use over time
O2 Blast
Get rid of a headache.

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