SSI ENRICHED AIR NITROX EXAM
QUESTIONS AND ANSWERS
When oxygen becomes toxic to body tissues, it most noticeably and immediately affects
the:
Bones and blood
Lungs and central nervous system
Central nervous system and feet
Lungs and circulation system - Correct Answers -Lungs and central nervous system
How is the ppO2 of a breathing gas calculated?
Multiply cylinder pressure by the fraction of nitrogen (FN2) in the cylinder
Multiplying ambient pressure by the fraction of oxygen (FO2) in the breathing gas
Dividing ambient pressure by the fraction of oxygen (FO2) in the breathing gas
Multiplying air pressure by the fraction of oxygen (FO2) in the breathing gas - Correct
Answers -Multiplying ambient pressure by the fraction of oxygen (FO2) in the breathing
gas
What does ppO2 mean?
Nitrox
Air
Partial pressure of oxygen
Partial pressure of nitrogen - Correct Answers -Partial pressure of oxygen
The threshold for CNS oxygen toxicity appears to be at a ppO2 of:
1.4 ata
1.6 ata
1.1 ata
32% - Correct Answers -1.1 ata
The risk of CNS Oxygen Toxicity becomes more substantial above:
A ppO2 of 1.6 ata
, A dive time of 30 minutes with air at 66 feet
A ppO2 of 1.4 ata
1000 feet of altitude - Correct Answers -A ppO2 of 1.6 ata
Pulmonary Oxygen Toxicity (the Lorrain Smith Effect) poses no real risk to recreational
divers because:
Pulmonary Oxygen Toxicity does not lead to problems.
The required exposure time before symptoms arise is well below the duration of most
sport dives
The risk of Pulmonary Oxygen Toxicity becomes more substantial on a single short dive
above a ppO2 of 1.6 ata
The required exposure time before symptoms arise is well beyond the duration of most
sport dives - Correct Answers -The required exposure time before symptoms arise is
well beyond the duration of most sport dives
Since CNS Oxygen Toxicity is among the greatest of risks in nitrox diving, you must be
able to recognize:
Its positive aspects in deep diving
Its warning signs and symptoms, both in yourself and others
Its warning signs and symptoms, only in yourself
Its treatment - Correct Answers -Its warning signs and symptoms, both in yourself and
others
The two most commonly used nitrox mixtures in recreational diving are:
EAN32/EAN36
EAN80/EAN20
EAN50/EAN60
EAN21/EAN79 - Correct Answers -EAN32/EAN36
Nitrox and the acronym EANx refer to mixtures with oxygen concentrations (FO2) higher
than:
40%
36%
32%
21% - Correct Answers -21%
Which special skills are required before you dive with nitrox?
None
Ability to carry up to two cylinders
Correct analysis of cylinder contents in the field and at the blending station
Buddy breathing - Correct Answers -Correct analysis of cylinder contents in the field
and at the blending station
QUESTIONS AND ANSWERS
When oxygen becomes toxic to body tissues, it most noticeably and immediately affects
the:
Bones and blood
Lungs and central nervous system
Central nervous system and feet
Lungs and circulation system - Correct Answers -Lungs and central nervous system
How is the ppO2 of a breathing gas calculated?
Multiply cylinder pressure by the fraction of nitrogen (FN2) in the cylinder
Multiplying ambient pressure by the fraction of oxygen (FO2) in the breathing gas
Dividing ambient pressure by the fraction of oxygen (FO2) in the breathing gas
Multiplying air pressure by the fraction of oxygen (FO2) in the breathing gas - Correct
Answers -Multiplying ambient pressure by the fraction of oxygen (FO2) in the breathing
gas
What does ppO2 mean?
Nitrox
Air
Partial pressure of oxygen
Partial pressure of nitrogen - Correct Answers -Partial pressure of oxygen
The threshold for CNS oxygen toxicity appears to be at a ppO2 of:
1.4 ata
1.6 ata
1.1 ata
32% - Correct Answers -1.1 ata
The risk of CNS Oxygen Toxicity becomes more substantial above:
A ppO2 of 1.6 ata
, A dive time of 30 minutes with air at 66 feet
A ppO2 of 1.4 ata
1000 feet of altitude - Correct Answers -A ppO2 of 1.6 ata
Pulmonary Oxygen Toxicity (the Lorrain Smith Effect) poses no real risk to recreational
divers because:
Pulmonary Oxygen Toxicity does not lead to problems.
The required exposure time before symptoms arise is well below the duration of most
sport dives
The risk of Pulmonary Oxygen Toxicity becomes more substantial on a single short dive
above a ppO2 of 1.6 ata
The required exposure time before symptoms arise is well beyond the duration of most
sport dives - Correct Answers -The required exposure time before symptoms arise is
well beyond the duration of most sport dives
Since CNS Oxygen Toxicity is among the greatest of risks in nitrox diving, you must be
able to recognize:
Its positive aspects in deep diving
Its warning signs and symptoms, both in yourself and others
Its warning signs and symptoms, only in yourself
Its treatment - Correct Answers -Its warning signs and symptoms, both in yourself and
others
The two most commonly used nitrox mixtures in recreational diving are:
EAN32/EAN36
EAN80/EAN20
EAN50/EAN60
EAN21/EAN79 - Correct Answers -EAN32/EAN36
Nitrox and the acronym EANx refer to mixtures with oxygen concentrations (FO2) higher
than:
40%
36%
32%
21% - Correct Answers -21%
Which special skills are required before you dive with nitrox?
None
Ability to carry up to two cylinders
Correct analysis of cylinder contents in the field and at the blending station
Buddy breathing - Correct Answers -Correct analysis of cylinder contents in the field
and at the blending station
