📘 Q.8 IAS Prelims 2021 — Environment & Ecology (Magnetite Pollution)🧷 Authentic Classroom Explanation by IAS Monk
📌 The Question:
Magnetite particles, suspected to cause neurodegenerative problems, are generated as environmental pollutants from which of the following?
- Brakes of motor vehicles
- Engines of motor vehicles
- Microwave stoves within homes
- Power plants
- Telephone lines
Select the correct answer using the code given below:
(a) 1, 2, 3 and 5 only
(b) 1, 2 and 4 only
(c) 3, 4 and 5 only
(d) 1, 2, 3, 4 and 5
✅ Correct Answer: (b) 1, 2 and 4 only
⚠️ Important correction: Option (d) is NOT correct.
🧠 Classroom Explanation:
Statement 1 — ✅ Correct
• Brake wear in motor vehicles is a major source of magnetite nanoparticles
• High friction + heat → formation of iron oxide particles (Fe₃O₄)
Statement 2 — ✅ Correct
• Engines of motor vehicles (especially diesel engines) emit magnetite through:
- Combustion processes
- High-temperature metal abrasion
Statement 3 — ❌ Incorrect
• Microwave stoves do not generate magnetite nanoparticles
• This is a common trap option in UPSC questions
Statement 4 — ✅ Correct
• Power plants (coal-based and other high-temperature industrial processes)
• Emit magnetite as part of particulate matter (PM) pollution
Statement 5 — ❌ Incorrect
• Telephone lines do not generate magnetite pollution
• No combustion, friction, or high-temperature process involved
👉 Hence, only 1, 2 and 4 are correct.
🔍 Curiosity Raiser:
🧠 Why is magnetite dangerous?
Because these particles are so tiny (nano-scale) that they can enter the brain directly via the olfactory nerve, bypassing the blood–brain barrier — a rare and alarming pathway!
📚 Enrich Notes (High-Value Prelims Add-on):
• Chemical nature: Magnetite = Fe₃O₄
• Size: Often < 200 nanometres
• Health risk: Linked to
- Alzheimer’s disease
- Parkinson’s disease
• Major sources: - Vehicle brakes & engines
- Coal-based power plants
- Industrial high-temperature processes
🚨 UPSC Trap Alert:
👉 Household appliances ≠ nanoparticle emitters
👉 Focus on combustion, friction, and high heat
🪶 IAS Monk Whisper:
When pollution becomes invisible, vigilance must become sharper.