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There are many sources of toxic gases in aviation including the following:
- a) combustion products from engines, b) fuels,
- c) lubricants,
- d) hydraulic fluids, e) anti?icing fluid, f) coolants,
- g) fire extinguishers, h) refrigerants,
- i) ozone, and
- j) agricultural chemicals.
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CHAPTER 5. TOXIC FUMES
- -all fumes detected in the aircraft are potentially lethal
- -commonest sources of fumes in transport aircraft
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-Fuel spilled from engines or machinery carried on board.
-additional hazard of explosion and fire.
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CHAPTER 5. TOXIC FUMES
- -Fumes usually arise during combustion
- - with many types of chemicals being produced.
- - Particularly hazardous fumes are given off when
- - hydrocarbons,
- -plastics,
- -polystyrene and
- -other synthetic products
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all these substances are common in aircraft interiors.
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CHAPTER 5. TOXIC FUMES
- Fumes may contain
- -carbon monoxide,
- -carbon dioxide,
- -hydrogen cyanide,
- -aldehydes,
- - ammonia,
- -benzene, -
- -phenol, -sulphur dioxide, and
- acrolein. Some of these gases may be lethal or at best, irritating and incapacitating.
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CHAPTER 5. TOXIC FUMES
- Symptoms of toxic gases or fumes
- -may mimic those of either hypoxia or hyperventilation
- - some toxic fumes directly causing hypoxia.
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CHAPTER 5. TOXIC FUMES
- Other symptoms include:
- a) eye and mucous membrane irritation, b) nausea,
- c) vomiting, d) confusion,
- e) disorientation, and f) headache.
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CHAPTER 5. TOXIC FUMES
- Onset of symptoms
- -may be insidious (eg. carbon monoxide) and may be confused with hypoxia.
- - can cause incapacitation without warning,
- - cause subtle impairment of the aircrew?s ability to fly the aircraft.
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CHAPTER 5. TOXIC FUMES
- If toxic fumes are involved,
- -odour and eye or throat irritation may be present.
- -These are not typical symptoms when exposed to hypobaric (hypoxic) hypoxia.
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CHAPTER 5. TOXIC FUMES
- smoke
- -will also impair vision
- - unable to read instruments or fly visually.
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CHAPTER 5. TOXIC FUMES
- CARBON MONOXIDE
- - is extremely hazardous
- - insidious nature and incapacitating effects.
- -Like hypoxic hypoxia, its onset can be very subtle.
- -binds to haemoglobin
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CHAPTER 5. TOXIC FUMES
- CARBON MONOXIDE
- Why Carbon monoxide more toxic
- -200 ? 300 times the affinity of oxygen and forms a molecule called carboxyhaemoglobin.
- - CO displaces oxygen from the Hb binding sites,
- - the oxygen carrying capacity of blood is reduced.
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CHAPTER 5. TOXIC FUMES
- CARBON MONOXIDE
- What other effects of CO.
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have a histotoxic effect on the nervous system with neurological symptoms being common.
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CHAPTER 5. TOXIC FUMES
- CARBON MONOXIDE
- Symptoms of CO poisoning may include:
- CNS Sx
- a) headache, b) weakness, c) dizziness,
- d) confusion,
- e) unconsciousness,
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f)shortness of breath
g) cherry?red flushing of the skin may also be noticed.
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CHAPTER 5. TOXIC FUMES
- CARBON MONOXIDE
- Continued exposure to carbon monoxide
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will often be fatal with treatment of severe poisoning usually requiring hyperbaric oxygen therapy.
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CHAPTER 5. TOXIC FUMES
- HYDROCARBONS
- -Fuels are made of many different types of hydrocarbons
- - carry the risk of explosion and fire.
- - greatest risk is on the ground during refueling operations.
- - can result in chemical burns.
- - Susceptible individuals can develop contact dermatitis.
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CHAPTER 5. TOXIC FUMES
- HYDROCARBONS
- Inhalation of fuel fumes
- -neurological effects,
- - usually headache and narcosis.
- -large doses can result in coma, convulsions and death.
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CHAPTER 5. TOXIC FUMES
- HYDROCARBONS
- Hydraulic fluids
- -are not as volatile as fuels.
- -can be aerosolized at high pressure and leak into the cabin after a system failure.
- - Most are non?toxic unless burnt,
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CHAPTER 5. TOXIC FUMES
- HYDROCARBONS
- Castor oil based fluid
- - Inhalation of these results in headache, dizziness, impaired vision and confusion.
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CHAPTER 5. TOXIC FUMES
- HYDROCARBONS
- Leaks due to mechanical failures
- = can contaminate cabin air with oil vapors or mists.
- -irritation of the eyes and respiratory tract,
- -headache, nausea,
- - pneumonitis(chemical inflammation of the lungs)
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CHAPTER 5. TOXIC FUMES
- HYDROGEN CYANIDE
- - extremely potent histotoxic agent.
- - produced in fires when plastics and synthetic materials burn.
- - interfere with all cells? ability to utilize oxygen in the mitochondria to produce energy (ATP) (oxidative phosphorylation).
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CHAPTER 5. TOXIC FUMES
- OZONE
- - tri?atomic form of oxygen, O3.
- - is a blue, unstable oxidant gas
- - toxic to humans.
- - occurs naturally in the stratosphere between 40 ? 140,000 feet.
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CHAPTER 5. TOXIC FUMES
- Ozone
- How is it produced
- Function
- -produced when UV ight reacts with molecular oxygen
- -protects the surface of the earth form UV radiation by absorption
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CHAPTER 5. TOXIC FUMES
- Ozone
- How else can Ozone be -can also be produced artificially by electrical discharges, such as electric motors and by lightening
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CHAPTER 5. TOXIC FUMES
- Ozone
- toxic effects mainly the respiratory tractjQuery110107462365925755379_1487673832556
- causes lung irritation
- - decreased lung function and coughing at just 1.0 ppm
- -10 ppm is enough to causes fatal leakage of fluid into the lungs (pulmonary oedema)?
- --is unstable and breaks down when heated
- - Air drawn from the engines in pressurised aircraft therefore has very little ozone in it
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CHAPTER 5. TOXIC FUMES
EMERGENCY ACTIONS FOR TOXIC FUMES
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- same as the corrective actions for hypoxia
- -Ventilate the cabin
- -Select emergency pressure on the regulator (ward flow of O2 preventing toxic gases from entering the mask.
- -Declare an emergency
- -Land as soon as possible.
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CHAPTER 5. TOXIC FUMES
- EMERGENCY ACTIONS FOR TOXIC FUMES
- Actions if you suspect toxic fumes in the cabin are:
- a) Select 100 % oxygen,
- b) Select emergency pressure, c) Toggle down,
- d) Check connections?push,
- e) Breathe at normal rate and depth, f) Declare an emergency,
- g) Descend and land ASAP, and h) Ventilate cabin.
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Unpressurised Aircraft not fitted with oxygen systems eg( CT?4B training aircraf, the following is recommended:
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? BOLD TYPE ACTIONS (AL2)
- ? Hot and cold air control knobs ? closed,
- ? Punkah louvres ? closed,
- ? Land as soon as practicable, and
- ? CO Indicator ? continue to monitor.
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? If CO indicator darkens further, heater used, or if fumes are present:
- ? Hot air control knob ? closed,
- ? Cold air control knob ? open,
- ? Punkah louvers ? open, and
- ? Land as soon as practicable.
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? Be alert for signs of Hypoxia.
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Figure 5?1 summarises the actions that should be taken following a smoke and fumes incident.
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FIGURE 5?1. SMOKE AND FUMES ACTION SUMMARY
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