Confined space is one of the most deadly spaces in the workplaces. It is because of confined spaces contain many potential hazards and have restricted exits way.

Related to confined spaces, OSHA requires that:
a. All confined spaces in the workplaces shall be identified.
b. Confined spaces shall be treated as hazardous until proven.
c. All confined space hazards shall be identified.
d. Appropriate response should be given to these hazards before entry.

Confined space hazards can be classified into hazardous atmosphere, physical hazard, chemical contact hazard and biological hazard. The hazard list below is hazards that are commonly identified in a confined space.

1. Oxygen rich (greater than 23.5%). This condition will introduce fire or explosion, especially when flammable vapor exists. So never use pure oxygen for ventilating a confined space. Use normal air supply only.
2. Oxygen deficient (less than 19.5%). Oxygen deficient or lack of oxygen can cause unconsciousness to death. Oxygen concentration in a confined space can be declined due to nitrogen intrusion, welding, grinding, oxidation, sandblasting or coating.
3. Oxygen and the existence of flammable vapors or gases can create flammable atmosphere. Chemical reaction and concentration of combustible dust may also create flammable atmosphere.
4. Toxic atmosphere. It is introduced when a toxic chemical or gas is stored in a tank/holder, when carbon monoxide or hydrogen sulphide is produced through decomposition or work being done in the confined space.
5. Corrosive atmosphere. Hydrochloric acid and ammonia are examples of chemicals that can build up a corrosive atmosphere.
6. Physical configuration hazards. The use of ladder and scaffolding, wet surface, uneven bottom, bends in tunnels, narrow area or poor lighting can cause physical hazards to the workers inside confined spaces.
7. Mechanical hazards. Mixing vessel, which is equipped with blades, can introduce mechanical hazard when workers come into the confined space (mixing vessel). Including in mechanical hazard is falling object.
8. Surface hazard, for instance slips and falls.
9. Noise hazards. Grinding work inside a confined space can result high level noise.
10. Vibration hazards.
11. Engulfment hazards. Engulfment hazard may happen when worker is entrapped by content of the confined space.
12. Temperature hazards. Cold temperature and heat create temperature hazard inside a confined space.

Always bear in mind that hazards identification shall be finished before entering a confined space. Then, provide appropriate hazard controls to these potential hazards afterward.