Magnetite particles, suspected to cause neurodegenerative problems, are generated as environmental pollutants from which of the following?
- 1.Brakes of motor vehicles
- 2.Engines of motor vehicles
- 3.Microwave stoves within homes
- 4.Power plants
- 5.Telephone lines
Select the correct answer using the code given below.
Answer & explanation
Answer: (b) 1, 2 and 4 only
Pollution-derived magnetite nanoparticles form when iron-bearing material is burnt or heated by friction, so they come from vehicle engine exhaust, brake wear and combustion at power stations. A 2016 study found such particles in human brain tissue and linked them to oxidative damage of the kind seen in Alzheimer's disease. Microwave ovens and telephone lines are not among the sources it names.
- ✓ 1. Frictional heating of brake pads produces high-temperature magnetite nanoparticles at the roadside.
- ✓ 2. Magnetite nanoparticles have been captured from the exhaust plume of diesel engines; combustion is the main source.
- ✗ 3. The study names open fires and poorly sealed cooking or heating stoves as indoor sources of magnetite nanoparticles; microwave ovens are not among them.
- ✓ 4. The study shows spherical, fused magnetite particles collected at a power station, an example of industrial combustion.
- ✗ 5. Telephone lines are not among the sources the study names; they carry electrical signals, not iron-oxide particles from combustion or friction.
Remember · Airborne magnetite nanoparticles come from combustion and friction: vehicle exhaust, brake wear, power plants, open fires. They have been found in human brain tissue.
Sources
- Maher et al., 'Magnetite pollution nanoparticles in the human brain', PNAS (2016), via PubMed Central ↗ “Frictional heating, e.g., of brake pads, can also produce high-temperature magnetite nanoparticles … TEM image of magnetite nanoparticles captured from the exhaust plume of a diesel engine. … Spherical magnetite particles, Didcot power station, comprising fused magnetite particles … Because enhanced ROS production is causally linked to neurodegenerative diseases such as Alzheimer’s disease, exposure to such airborne PM-derived magnetite nanoparticles might need to be examined as a possible hazard to human health.”
Question and answer: UPSC's official GS Paper I (2021, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 1 Oct 2026 (how we verify). ·