OXYGEN IS ESSENTIAL FOR LIFE

The industrial gas industry is very concerned about the incidents that industrial gas companies and users of inert gases continue to report each year, where the direct cause has been lack of oxygen resulting in asphyxiation. There are two essential points to remember related to oxygen-deficiency incidents involving inert gases:

? Incidents resulting from oxygen deficiency due to inert gases happen unexpectedly and the reactions of personnel can be incorrect; and

? Incidents involving asphyxiating atmospheres are always serious, if not fatal. 

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Oxygen is essential for life Oxygen is the only gas that supports life. The normal concentration of oxygen in the atmosphere is approximately 21%. The ability to concentrate, think, and make decisions is impaired when the oxygen concentration falls only slightly below atmospheric levels. These effects are not noticeable to the affected individual. If the oxygen concentration in the air decreases or if the concentration of any other gases increases, a situation is rapidly reached where the risks of asphyxiation are significant. For this reason, any depletion of oxygen below 19,5% shall be treated with concern. An oxygen-deficient atmosphere can bring about unconsciousness without warning. In as little as one or two breaths, an individual's life can be endangered by low oxygen intake. Table 1 describes a quantitative evaluation of the health effects and symptoms that can be expected in humans who inhale air containing less than normal levels of oxygen.

Inert gases give no warning It is essential to understand that with inert gases, asphyxia can occur with no warning.  Inert gases are odorless, colorless, and tasteless. They are undetectable and can, therefore, be a great deal more dangerous than toxic gases such as chlorine, ammonia, or hydrogen sulfide, which can be detected by their odor at very low concentrations. The asphyxiating effect of inert gases occurs without any preliminary physiological sign that could alert the victim. Lack of oxygen can cause vertigo, headache or speech difficulties, but the victim is not capable of recognizing these symptoms as asphyxiation. Asphyxiation leads rapidly to loss of consciousness—for very low oxygen concentrations this can occur within seconds. YOU CAN DO A LOT TO AVOID INCIDENTS-PRESS HERE

Table 1—Effects at various oxygen breathing levels

20.9 Normal (below 19.5% is considered oxygen deficient)

19.5 – 10 Increased breathing rates; accelerated heartbeat; and impaired attention, thinking, and coordination

10 – 6 Nausea, vomiting, lethargic movements, and perhaps unconsciousness

<6 Convulsions, then cessation of breathing, followed by cardiac stand still

Inert gases act quickly In any incident when the supply of oxygen to the brain is affected, prompt emergency treatment is critical. Medical treatment such as resuscitation if given promptly can prevent irreversible brain damage or even death in some circumstances. An emergency rescue procedure shall be planned in advance to avoid the possibility of the rescue team becoming victims also. Unplanned interventions resulting in the fatalities of would-be rescuers have occurred on multiple occasions. Workers suddenly involved in emergency activities shall not allow emotions to override safe work procedures and training. Only qualified and trained personnel equipped with the necessary personal protective equipment (PPE) should attempt a rescue in accordance with the company’s rescue procedures.

The ambiguity of inert gases An inert gas is often thought to be a harmless gas. Individuals shall be aware of the ambiguity of the expression “inert gas,” sometimes called “safety gas,” when it is used to prevent fire or explosion. Inert gas can be applied as a safety gas, but it is not without its own risks (such as asphyxiation).

Awareness with regard to inert gases and oxygen depletion Considering the hazards of inert gases, it is essential to provide all those who handle or use inert gases with the information and training necessary regarding safety instructions. This includes the means of prevention and procedures to be followed to avoid incidents, as well as planned rescue procedures to be implemented in the event of an incident.

Typical situations with inert gas and/or oxygen depletion hazards Poorly ventilated areas, confined spaces, areas immediately outside confined spaces, enclosures, and low-grade areas can contain oxygen-deficient atmospheres. Work performed in confined spaces shall follow specific regulatory requirements. NOTE Oxygen depletion can also be caused by the presence of any gas other than oxygen such as flammable gas or toxic gas. 

Confined or enclosed spaces An oxygen-deficient atmosphere can bring about unconsciousness without warning. In as little as one or two breaths, an individual's life can be endangered by low oxygen intake. Oxygen-deficient atmospheres are not limited to confined spaces, they also can exist outside of a confined space opening.

Examples of areas where oxygen-deficient atmospheres can exist include:

? storage tanks, vessels, reservoirs, the inside of cold boxes of liquefaction equipment, cold storage

rooms, warehouses with fire suppressant atmospheres;

? outside confined space openings;

? analyzer or instrument cabinets, small storage sheds, temporary/tented enclosures, or spaces where welding protective gas is used; and

? underground works and trenches/pits deeper than 1 m (3.28 ft).

Use of inert cryogenic liquids The use of inert cryogenic liquids such as nitrogen or helium is accompanied by two primary hazards:

? They are very cold (–196 °C [–320.8 °F] for nitrogen and –269 °C [–452.2 °F] for helium) and can cause cold burns on contact with the skin; and

? Once vaporized, both products will generate a large volume of cold inert gas (for example, 1 liter of liquid nitrogen yields 0.65 m gaseous product) that will displace ambient air, causing oxygen deficiency, and could accumulate in low points. In processes where cryogenic liquids are handled and vaporization takes place, care shall be taken to avoid situations where personnel is exposed to oxygen deficiency.