Worker Safety: Detecting Gas in Hazardous Environments

Workers in a wide variety of fields are often placed in potentially hazardous situations when working in confined spaces where gases can easily accumulate. Gas-related injuries pose a serious threat to workers operating in any situation where there is limited movement of fresh air.

Besides the restriction of movement and air quality limitations, these environments are typically not conducive to employees spending a great deal of time in them, and should an emergency arise, it may not always be easy to make a hasty exit. It is the employers responsibility to ensure the safety of their workers, and thus to monitor hazardous situations to prevent accidents. This usually involves testing and monitoring the environment with a gas detection system.

Risks associated with exposure to hazardous gases are classified into three categories:

• combustible/explosive gases
• toxic gases
• low or high oxygen levels

Flammable gas risks

In order for gas to ignite, there must be a sufficient concentration of flammable gas or vapor present -- often referred to as the lower explosive limit (LEL) which is typically <5% of the total volume. When gas concentrations reach or exceed these levels, it will readily combust if there is a spark or other suitable ignition source. The environment is usually classified as 'hazardous' when concentrations reach 10% LEL.

There are many environments that pose a danger to workers, including working in or around storage containers that have held hydrocarbon oils or fuels, fuel or gas pipelines, compressed gas cylinders, engine-driven machinery/equipment; or when working in confined spaces such as sewers, pits and other subterranean locations where methane can accumulate.

Toxic gases and vapors

Depending on the environment, and the nature of the work being undertaken, workers operating in confined spaces can be exposed to a wide variety of toxic gases and chemical vapors. It is the employers responsibility to ensure that a risk assessment is conducted to ascertain what toxic gases or vapors their employees risk being exposed while carrying out their duties, and to take the necessary precautions to prevent accidents.

Some potential hazards include carbon monoxide poisoning as a result of excessive buildup of exhaust fumes from generators or other powered plant, machinery and/or vehicles. Workers operating in confined spaces underground can be exposed to toxic levels of carbon dioxide and hydrogen sulphide released as organic matter within the soil decomposes.

Oxygen levels that are too high or too low

When oxygen levels rise or drop below the normal concentrations (20.9%) found in fresh air, it can pose a risk to human health. Oxygen levels below 19.5% or above 23.5% are considered hazardous. When oxygen levels drop to 17% it can lead to a noticeable impairment of physical and mental ability. Should oxygen levels drop further still, a person exposed will lose consciousness with death occurring swiftly thereafter.

When working in confined spaces that lack ventilation, simply breathing can quickly reduce the available oxygen, causing oxygen levels to drop rapidly. As combustion requires and utilizes oxygen, operating engine-driven machinery or using equipment such as welding torches can also reduce oxygen levels to a point where it is hazardous for workers.

By the same token, there is also a safety risk when workers are exposed to environments where oxygen levels are too high. The effects and symptoms are similar as to when a person is confined to an area where oxygen levels are too low -- impaired cognitive ability and functioning. Furthermore, environments that have high oxygen levels also pose a high fire risk, including spontaneous combustion of materials that wouldn't normally ignite. High oxygen levels are typically caused by addition of oxygen from leaking oxygen cylinders used for welding or from breathing apparatus used to provide workers with oxygen in low-oxygen environments.

Preventing accidents by detecting gas

To ensure worker safety, it is paramount that employers install gas detectors to alert their employees to potential hazards when working in confined spaces or other hazardous environments. A gas detector, such as the H2S Infrared Gas Sensor by Otis Instruments can monitor hazardous environments and alert workers when conditions become dangerous. These gas detectors are available in both a wired and wire-free version, and have lots of features that make them a truly remarkable gas detection system.