Winter in Delhi brings heavy smog and very poor air quality. The pollution causes serious health problems for Delhiites and nearby areas. Burning fossil fuels, transport, industries, and agriculture all add to the dirty air. The worst enemy is particulate matter (PM), tiny particles in the air that cause strokes, heart, and lung diseases. PM10 are particles 10 microns or smaller that harm health when breathed in. Even smaller are PM2.5 and diesel particles under 1 micron which are very dangerous, especially for children. To fight pollution, the Commission for Air Quality Management now requires schools to close during severe pollution phases (Phase 3 and 4) in Delhi and NCR. Public offices must also stagger work timings under Phase 3. Originally, states had discretion on these actions, but now these are mandatory. The Supreme Court has confirmed the right to clean air as part of the fundamental right to life (Article 21). This grew out of cases since the 1970s that linked environment protection with human rights. Articles 48A and 51A(g) of the Constitution make it a duty for the state and citizens to protect the environment. Courts have used Public Interest Litigations to fight pollution and balance development and ecology. Laws, like the Environment Protection Act of 1986, define environment as air, water, land, and everything related. In disasters, the Supreme Court established "absolute liability" for polluters causing damage, meaning they must pay regardless of fault. The "precautionary principle" calls for action even if full scientific proof is missing, to prevent harm. The "polluter pays principle" means polluters must bear cleanup costs. Another key idea is the "public trust doctrine", where the state holds natural resources as a trustee for the people and must not misuse them. The Supreme Court recently recognized the right to protection from climate change effects under Articles 14 and 21. Despite government efforts, pollution problems remain serious. Experts say it is time to include the right to a clean, healthy environment expressly in the Constitution so both state and citizens share responsibility. The article was written by the President of Centre for Applied Research in Governance, Delhi.