🔍 Key Concepts

• Toxic effects of hydrogen sulfide (H₂S) on the human body at different concentrations • Difference between early symptoms (low exposure) and severe outcomes (high exposure or prolonged exposure) • Why confined spaces and low-lying areas on tankers make H₂S especially dangerous to personnel

💭 Think About

• Think about what happens first to a person who inhales a toxic gas like H₂S in small amounts versus what can happen if exposure continues or the concentration is very high. • Ask yourself: does hydrogen sulfide only cause mild symptoms, or can it also interfere with breathing and the central nervous system? • Consider whether exam questions on toxic gases usually focus on one specific effect or on the full range of possible health impacts.

✅ Before You Answer

• Review the progression of H₂S symptoms: irritation, dizziness, respiratory effects, loss of consciousness, and potential fatality. • Confirm that asphyxiation means the body is deprived of oxygen, which can occur even if there is still air present, due to a toxic gas interfering with normal breathing. • Before choosing an option, check whether more than one listed effect is medically associated with hydrogen sulfide exposure.