The AQI of Delhi during winter often exceeds 400. What is the primary scientific and policy-based reason for such critical levels?
Show answer & explanation
Correct answer: C
Explanation
Solution: The correct answer is Thermal inversion and transboundary stubble burning from Punjab and Haryana.
Explanation:
☛ During winter, Delhi experiences meteorological conditions known as thermal inversion (or temperature inversion), where a layer of warm air traps cooler air containing pollutants near the ground.
☛ This phenomenon, combined with low wind speeds, severely restricts atmospheric dispersion and vertical mixing of pollutants.
☛ Simultaneously, post-harvest paddy stubble burning in neighboring agrarian states like Punjab and Haryana releases massive amounts of particulate matter (PM2.5 and PM10).
☛ North-westerly winds transport these dense plumes of smoke directly across the Indo-Gangetic Plains into the National Capital Region (NCR), pushing the Air Quality Index (AQI) into the 'Severe' (401–500) category.
Extra Exam-Relevant Facts:
☛ Air Quality Index (AQI): Developed by the Central Pollution Control Board (CPCB) under the 'Swachh Bharat Abhiyan' in 2014, featuring six categories: Good, Satisfactory, Moderate, Poor, Very Poor, and Severe.
☛ Eight Key Pollutants: AQI tracks eight pollutants: PM10, PM2.5, NO2, SO2, CO, O3, NH3, and Pb.
☛ CAQM: The Commission for Air Quality Management in the National Capital Region and Adjoining Areas was established under an Act in 2021 to coordinate and implement mitigation measures.
☛ GRAP: The Graded Response Action Plan is an institutional emergency measure implemented in Delhi-NCR based on rising AQI levels.
Important One-Liners for Upcoming Exams:
☛ When was the National Clean Air Programme (NCAP) launched in India? → January 2019
☛ Which statutory body monitors air quality across India under the Air Act, 1981? → Central Pollution Control Board (CPCB)
☛ What is the air quality status when the AQI ranges between 401 and 500? → Severe
☛ Which mobile application was launched by the CPCB to track real-time AQI across Indian cities? → SAMEER App
☛ Which bio-decomposer developed by ICAR-IARI is used to decompose crop stubble in fields? → Pusa Bio-Decomposer