Asphyxial deaths: sewer gas deaths: practice question

A Forensic Medicine 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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Forensic Medicine · Asphyxial deaths: sewer gas deaths

Sample item

A worker collapses after entering a deep septic tank; a colleague climbs in to rescue him and also collapses. Sewer gas with hydrogen sulphide is suspected. What is the correct approach for the next rescuers?

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

The answer and the reasoning

A. Enter only with self-contained breathing apparatus after ventilating the chamber

Hydrogen sulphide, with methane and carbon dioxide, builds up in sewers and tanks and is a chemical asphyxiant that blocks cellular respiration. At high concentration it paralyses smell, so the odour disappears and gives false reassurance. Rescuers need breathing apparatus and ventilation, as many deaths are of would-be rescuers.

Option by option

  • A. Enter only with self-contained breathing apparatus after ventilating the chamber (correct)

    Correct. Without protection the rescuer becomes the next victim.

  • B. Rely on the rotten-egg smell as a warning of danger

    Smell is lost at high concentrations through olfactory paralysis.

  • C. Enter wearing a surgical mask

    A surgical mask does not filter gases.

  • D. Enter immediately holding the breath

    Holding the breath gives only seconds and the rescuer cannot work effectively.

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.

More Forensic Medicine questions

Questions about this Forensic Medicine question

What is the answer to this Forensic Medicine question?

The best answer is A, Enter only with self-contained breathing apparatus after ventilating the chamber. Hydrogen sulphide, with methane and carbon dioxide, builds up in sewers and tanks and is a chemical asphyxiant that blocks cellular respiration.

Why is "Rely on the rotten-egg smell as a warning of danger" not the answer?

Smell is lost at high concentrations through olfactory paralysis.

Why is "Enter wearing a surgical mask" not the answer?

A surgical mask does not filter gases.

Why is "Enter immediately holding the breath" not the answer?

Holding the breath gives only seconds and the rescuer cannot work effectively.

What concept does this question test?

It tests Asphyxial deaths: sewer gas deaths in Forensic Medicine. At high concentration it paralyses smell, so the odour disappears and gives false reassurance. Rescuers need breathing apparatus and ventilation, as many deaths are of would-be rescuers.

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 Asphyxial deaths: sewer gas deaths?

Learn postmortem changes with their timelines, and toxicology as poison, sign, test and antidote. Then use the flashcards and the other Forensic Medicine 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.