Air and Water Quality

Overview

Air and Water Quality is a core environmental science topic for WB TET Paper II, bridging chemistry, biology and environmental awareness. Questions typically test your knowledge of atmospheric composition, types and sources of pollution, water treatment basics and conservation strategies. This topic connects directly to the broader Environmental Studies and Science pedagogy themes in the syllabus.

For the exam, you must know the exact percentage composition of atmospheric gases, distinguish between primary and secondary pollutants, understand the water cycle and its disruption by human activity, and recall specific conservation measures. Expect 2–4 questions combining factual recall with application-based scenarios about pollution control or purification methods.

Mastering this topic also prepares you for pedagogy questions on teaching environmental concepts through experiments, field visits and real-life examples—a key NCF emphasis for upper-primary science.

Key Concepts

• **Composition of air**: Air is a mixture of gases—nitrogen (78%), oxygen (21%), argon (0.93%), carbon dioxide (0.04%) and traces of water vapour, neon, helium and ozone.

• **Air pollution defined**: Introduction of harmful substances (particulates, gases, biological molecules) into the atmosphere that cause disease, damage to living organisms or climate change.

• **Primary vs secondary pollutants**: Primary pollutants are emitted directly (CO, SO₂, NOₓ, particulate matter). Secondary pollutants form by reactions in air (ozone at ground level, PAN—peroxyacetyl nitrate).