Risk inside confined space

risk inside confined space

risk inside confined space

Risk inside confined space is common. Performing tasks in confined spaces may result in workers being exposed to a variety of hazards, depending on the nature of the work to be performed, the equipment to be used, the presence of hazardous substances or microorganisms or the geometry and configuration of the confined space itself. Thus, risks in confined spaces can be subdivided into two global categories. You can see also this What is confined space and its characteristics.

1. Mechanical Risks

2. Specific Risks

Now we will discuss mechanical and specific risks one by one.

1. Mechanical Risks


Mechanical Risks are caused by several physical factors, such as the characteristics of the confined space, its structural stability, the type and duration of the work to be done, among others. Examples of mechanical hazards, Risk inside confined space but not limited to:

  • Risk of falling from a height.
  • Risk of drowning.
  • Electrocution risk.
  • Hearing loss.
  • Risk of a partial or total collapse of structures.
  • Risk of falling objects/debris.
  • Risk of prolonged and excessive fatigue.

2. Specific Risks


Specific risks are directly related to atmospheric, environmental, chemical and biological conditions within the confined space. Examples of specific risks, but not limited to:

Choking Hazard

The below table is defining risks at different concentrations of oxygen level inside confined space.

Concentration (%) Risks
21%Normal O2 concentration in the air
18%Loss of muscle coordination and acceleration of breathing rhythm
17% Loss of consciousness
12-16%Dizziness, headache, loss of muscle coordination and loss of consciousness
6-10%Nausea, loss of consciousness and death

Chemical Hazards

Examples of Toxic Gas Dangers / Risks / Possible effects
Hydrochloric Acid (HCL) Corrosive, Toxic – affects the respiratory tract
Hydrofluoric acid (FH) Corrosive, Toxic – effects the respiratory tract
Sulfuric Acid (SO4H2) Corrosive, Toxic – effects the respiratory tract
Ammonia (NH3) Toxic – effects the respiratory tract
Argon (Air) Replaces oxygen Choking
Chlorine (Cl) Toxic Aggressive to eyes and affects the respiratory tract
carbon dioxide (CO2)
Toxic Replaces Oxygen – Choking
Sulphur Dioxide (SO2) Toxic – severely affects the respiratory tract
Nitrogen dioxide (NO2) Toxic – severely affects the respiratory tract
Carbon Monoxide (CO) Toxic – high risk of loss of consciousness and asphyxiation
Nitrogen (N) Replaces oxygen – choking
Ozone (O2) Toxic – effects the respiratory tract
Hydrogen Sulphide (H2S) High toxicity – severely affects the airways and may cause lung failure

Fire and Explosion Hazards

Flammable atmosphere Explosive atmosphere
Fuel – flammable products and vapors present in confined space or formed by chemical reactions Causes – high concentrations of combustible vapors, pressure equipment, and high oxygen concentrations
Flashpoints – electrical discharges, welding and cutting jobs, human error Flashpoints – electrical discharges, welding and cutting jobs, human error

Environmental Risks

  • Lack of or insufficient lighting
  • Excessively low or high temperature
  • High humidity
  • A high volume of dust.

Biological Risks

  • Bacteria
  • Virus
  • Fungi
  • Pests

In addition to the risks mentioned above, due to possible unfavorable configurations and access characteristics, confined spaces may also entail additional risks inherent in the increased difficulty of rescuing the workers involved in confined space work. See also How to rescue in confined space

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3 thoughts on “Risk inside confined space

  1. Nice acknowledgement about the confined space, I most like this article pls continue sharing such type of safety related activities.

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