Air pollution damage to plants is characterized by which symptom?

• A. Yellow blotches on leaves
• B. Purple blotches near the veins
• C. White powder on leaf surfaces
• D. Brown margins on leaves

Answer: (B)

Air pollution injury often triggers a pigment response in leaves. Oxidative stress from pollutants like ozone can cause plants to produce protective pigments, such as anthocyanins, which give leaf tissue a reddish-purple coloration. These purple blotches tend to appear near the veins where damage and pigment buildup are more noticeable, making this symptom a characteristic sign of pollution-related stress.

Other options point to different problems: yellow blotches can come from nutrient imbalances or pests, white powder indicates a fungal disease like powdery mildew, and brown margins usually signal water stress or edge damage rather than pollution.