Environmental health: occupational compressed air illness: practice question

A PSM question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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PSM · Environmental health: occupational compressed air illness

Sample item

A commercial diver develops joint pains and breathlessness soon after a rapid ascent. What is the underlying mechanism?

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

D. Nitrogen bubbles released from tissues on rapid decompression

Under pressure, nitrogen dissolves in tissues, and on rapid decompression it comes out of solution as bubbles that cause joint pain, breathlessness and neurological damage. This is decompression sickness or caisson disease. Slow staged ascent prevents it.

Option by option

  • A. Hydrogen sulphide inhalation

    Hydrogen sulphide is a toxic gas of sewers and wells, unrelated to diving.

  • B. Oxygen toxicity

    Oxygen toxicity causes seizures and lung injury at high partial pressures during the dive.

  • C. Carbon monoxide poisoning

    Carbon monoxide poisoning produces headache and cherry-red skin, not joint pain after ascent.

  • D. Nitrogen bubbles released from tissues on rapid decompression (correct)

    Correct. Nitrogen bubbles from rapid decompression cause decompression sickness.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

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Questions about this PSM question

What is the answer to this PSM question?

The best answer is D, Nitrogen bubbles released from tissues on rapid decompression. Under pressure, nitrogen dissolves in tissues, and on rapid decompression it comes out of solution as bubbles that cause joint pain, breathlessness and neurological damage.

Why is "Hydrogen sulphide inhalation" not the answer?

Hydrogen sulphide is a toxic gas of sewers and wells, unrelated to diving.

Why is "Oxygen toxicity" not the answer?

Oxygen toxicity causes seizures and lung injury at high partial pressures during the dive.

Why is "Carbon monoxide poisoning" not the answer?

Carbon monoxide poisoning produces headache and cherry-red skin, not joint pain after ascent.

What concept does this question test?

It tests Environmental health: occupational compressed air illness in PSM. This is decompression sickness or caisson disease. Slow staged ascent prevents it.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Environmental health: occupational compressed air illness?

Practise biostatistics with small calculations until sensitivity, predictive values and risk measures are automatic. Then use the flashcards and the other PSM questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.