Explanation

Statement I is correct. Dust particles are more concentrated in subtropical and temperate regions due to a combination of factors. These regions are home to major arid and semi-arid climates, with large deserts such as the Sahara, Arabian Desert, and Thar Desert — all located in subtropical zones — acting as prime sources of atmospheric dust. The lack of vegetation cover and strong dry winds promote the suspension of dust particles in the atmosphere. In contrast, equatorial regions are humid and densely vegetated, where frequent rainfall and plant cover suppress dust. Polar regions are cold and ice-covered, which similarly limits dust production and suspension.

Statement II is incorrect. Subtropical regions are not characterized by less dry winds — quite the opposite. The subtropical high-pressure belts are associated with descending air masses, which create dry, stable, and arid conditions. These descending air currents result in low humidity, clear skies, and strong dry winds — precisely the conditions that make subtropical regions dustier, not less so. It is these very dry winds that explain why dust concentration is higher in subtropical and temperate areas. Statement II therefore not only fails to explain Statement I — it directly contradicts the actual atmospheric dynamics of subtropical regions.

Therefore, Statement I is correct but Statement II is incorrect.