You may work for years without any health effect, and then suddenly develop a severe, sometimes life-threatening reaction to even very small exposures that do not hurt other people. Some people become so allergic that they cannot do their jobs unless the sensitizers are eliminated. Confined Spaces A confined space is an area with small openings for a worker to enter and exit and is not designed for regular work. Examples of confined spaces include manholes, sewer digestors and silos, tunnels, pumping stations, and utility vaults. There are many hazards in confined spaces.
Workers can become unconscious and die from a lack of oxygen.
At other times, there may be too much oxygen, or other chemicals can be present that can catch fire or explode. Poisonous gases and vapors, such as hydrogen sulfide or carbon monoxide, may also build up in a confined space. Confined spaces can also pose physical hazards. They can be very hot or cold. Such an area can be very loud.