UGC NET Questions (Paper – 1)

Fine particulates with diameters less than 2.5 micrometres can bypass the upper respiratory defences and reach the deepest parts of the lungs. From there, some particles or their components can move into the bloodstream. These processes are associated with inflammation, aggravated asthma, heart attacks and other serious health outcomes. Hence, the main reason PM2.5 is considered particularly harmful is its ability to penetrate deeply and affect multiple organ systems, as stated in Option C.

Option A:
Option A is incorrect because many PM2.5 particles are too small to be seen with the naked eye. Their danger lies in their invisibility and ability to reach deep into the lungs, not just in causing eye irritation.

Option B:
Option B is incorrect because fine particles do not simply settle quickly; they can remain suspended in the air for long periods and be easily inhaled. Their persistence in the air increases the duration and likelihood of exposure.

Option C:
Option C is correct as it identifies the key health pathway: deep penetration into the respiratory tract and possible entry into the bloodstream. This ability to affect both the lungs and the cardiovascular system makes PM2.5 especially hazardous.

Option D:
Option D is incorrect since PM2.5 can contain toxic metals, organic compounds and secondary aerosols. These components are far from harmless and have well-documented long-term health impacts.