sign death by nitrogen.pdf

Death by Nitrogen

Every year people die in nitrogenrich/oxygen deficient atmospheresbecause of ignorance, attitude andfailure to adhere to safe work practices.

N2 vs O2

Nitrogen itself is not toxic – it exists inair at 78%.

O2 in the air is typically 20.8%

When nitrogen concentration increases,oxygen concentration decreases.

Nitrogen kills by oxygen depletion. Note: any compressed gas can also decrease O2 concentration

in an enclosed space by replacing O2.

Facts & FiguresLiquid Nitrogen

One litre liquid gives 700 litres of gas.

Nitrogen is heavier than air so accumulates atground level.

When liquid N2 is exposed to air the cloudyvapour that you see is condensed moisture,not N2 gas. N2 gas is invisible.

OHSA recommend at least 6 changes of airper hour when using liquid N2.

Other risks: pressure, frost, confuse LELdetectors.

Definitions

Osmosis: If you have a concentratedmixture on one side of a permeablemembrane and a dilute mixture on the other,the flow of material will be from concentratedto the dilute side.

Hypoxia : reduction of O2 supply to thetissues.

Anoxia: lack of O2 supply to the tissues.

Transport of oxygen

O2 flows from high concentration tolow concentration.

Concentration of O2in the lungs is high

Concentration of O2 in thetissues and Brain is lower.


Oxygen Osmosis

Oxygen is transported from the lungs to cells, tissue andbrain via Osmosis.


O2 deficient air isinhaled

Concentration of O2 in the tissuesand Brain is higher than the lungs


Concentration of O2 equalises throughout the body.























What happens when youbreathe in nitrogen?

• Reverse Osmosis

• Lungs take O2 from the blood stream which in turn takes it from the brain.

• Brain becomesstarved of oxygen –you pass out

• It only takes onebreath!

What happens when youbreathe in nitrogen?

Physiological effectsOxygen (%vol) Effects & Symptoms

23.5 Maximum “Safe Level” OSHA

21 O2 level in air

19.5 Minimum permissible O2 level

15-19 First signs of hypoxia. Decreased ability to work strenuously. May induceearly symptoms in persons with coronary, pulmonary or circulatoryproblems.

12-14 Respiration increases with exertion, pulse up, impaired muscularcoordination, perception & judgement.

10-12 Respiration further increases in rate & depth, poor judgement, lips blue.

8-10 Mental failure, fainting, unconsciousness, ashen face, blueness of lips,nausea, vomiting, inability to move freely.

6-8 8 minutes – 100% fatal

6 minutes – 50% probably fatality rate

4-6 Coma in 40 seconds, convulsions, respiration ceases, death

How long does it take to havean effect?

When a person enters an oxygen deprivedatmosphere the oxygen level in the arterialblood drops to a low level within 5-7 seconds.

Loss of consciousness follows in 10-12seconds.

Heart failure and death ensue if person doesnot receive any oxygen in 2-4 minutes.

What If I hold my breath?

Holding your breath causes the oxygenin your blood to be used up. If youthen inhale the inert atmosphere,suffocation and death will follow inmost cases (INRS ED 632)

Do I have to be in an enclosedspace to be at risk?

No. Any situation where you can breatheoxygen deficient air has the same effect.

Incident at Texas City where individual wasworking on top of reactor. He leaned over,got a blast of pure N2 and pitched forwardinto the vessel unconscious.

When cold, Nitrogen is more dense than airso lower concentration at floor level. If youlean down into a liquid nitrogen spillage youare also at risk.

What if I see a colleague whois unconscious?

Call emergency services.

Do not enter the area without selfcontained breathing apparatus.

Over 50% of workers who die inconfined spaces are attempting torescue other workers.

What about Helium?

Helium is much less soluble in water than many othergases, such as nitrogen. The low solubility means itdoes not enter the blood stream, even underpressures commonly experienced by deep sea divers

Why is He added to SCUBAtanks?

Under water, a scuba diver is subjected to added pressure, upto 10 times normal atmospheric pressure at a depth of 300feet. Under these conditions, greater amounts of oxygen enterinto the bloodstream. If the concentration becomes too high,oxygen poisoning can result, with symptoms that includeconfusion, impaired vision and nausea. So, under highpressures, oxygen must be diluted with some other gas, usuallyhelium.

Why isn’t N2 added to SCUBA tanks?

Nitrogen is much more soluble in water than Helium. At the elevated pressures experienced by divers,larger amounts of nitrogen will dissolve in the bloodcausing nitrogen narcosis. Dissolved nitrogen alsocan cause a painful condition, called "the bends" if adiver makes too rapid an ascent. As the pressuredecreases, the dissolved gas can form bubbles thatcan stop circulation in capillaries and damage thenervous system.

What about inhaling heliumfrom balloons?

A popular party trick is to inhale helium from ahelium filled balloon and talk like Mickey Mouse.

Sound is produced by our vocal cords throughvibration. The air around our vocal cords is vibrated,and we interpret this as sound. Helium is a muchlighter gas than air, allowing the vocal cords tovibrate much faster, giving a high pitch voice. As thehelium is replaced by regular air the voice returns tonormal.

So it’s safe to inhale Helium?

NO!! Breathing in any O2 deficient gas or air will cause hypoxia.

Many people have suffered hypoxia by inhaling helium fromballoons at parties, and some have even died after inhaling theentire contents of a balloon.

Even more dangerous are compressed He bottles which are nowavailable to the pubic for party balloons. People are dying fromaneurisms after inhaling He from a pressurised container whileattempting party tricks.

BOC are campaigning to restrict the availability of helium to thegeneral public to prevent further fatalities.

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