🔍 Key Concepts

• Hydrogen sulfide (H2S) toxicity at high concentrations and how it affects the nervous system and breathing • The difference between immediate life‑threatening effects and less serious irritation symptoms • How respiratory paralysis compares to temporary discomfort like eye or balance problems

💭 Think About

• Which of these choices describes an effect that would kill someone very quickly if the gas concentration is high enough? • Which symptoms (eye inflammation, dizziness, muscle contractions, breathing failure) are more like warning/irritation signs, and which is a direct, immediate threat to life? • Think about confined‑space H2S incidents: what is the main reason rescuers can suddenly collapse after one or two breaths?

✅ Before You Answer

• Identify which option shows loss of ability to breathe on your own, not just discomfort or mild poisoning. • Eliminate options that sound like localized irritation (particularly to eyes) rather than a systemic, fatal effect. • Decide which option best matches the idea of sudden collapse and rapid unconsciousness reported in high‑H2S accidents.