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Relevance: GS-II (Governance) | GS-III (Environment) | Source: The Hindu
The Context: Despite the Supreme Court allowing only green crackers within strict timing windows, widespread bursting of traditional firecrackers past 10 p.m. pushed Delhi’s night-time PM2.5 levels to 150–200 times the WHO safe limit. However, a lucky shift in wind direction blocked farm fire smoke and cleared the toxic air faster than expected the next day.
1. Ground Realities: Extreme Spikes & Missing Data
- The 200x PM2.5 Surge: Fine inhalable particles (PM2.5) that can enter the lungs and bloodstream hit extreme levels—reaching 2,597 µg/m³ at Patparganj (173x the WHO 24-hour safe limit of 15 µg/m³) and 3,008.4 µg/m³ at NSUT West Campus (roughly 200x the limit).
- The Missing Data Row: Crucial air quality readings went missing from several government monitoring stations right during the midnight pollution peak. Experts noted that missing peak-hour readings artificially make the 24-hour average Air Quality Index (AQI) look better than reality.
- Stubble Burning Trends: While Punjab logged its highest single-day spike of the season (1,152 farm fires) on Sunday, the cumulative seasonal fire count up to November 9 (4,657) remained the second-lowest since 2020.
2. Core Geography: How Wind Patterns Saved the Day
- The Winter Inversion Trap: Normally, dropping winter temperatures and calm winds trap vehicle fumes, dust, and smoke close to the ground across the Indo-Gangetic Plains.
- North-Westerly vs. Easterly Winds: Usually, north-westerly winds blow stubble burning smoke straight from Punjab and Haryana into Delhi. However, on Deepavali afternoon, the winds reversed to an easterly and south-easterly direction and picked up speed.
- Low Stubble Share & Fast Dispersion: Because the easterly winds blocked the farm smoke corridor, stubble burning contributed just 5.1% to Delhi’s PM2.5 that day. The faster wind speed also flushed out the heavy midnight firecracker smoke by morning, keeping the overall AQI at 344 (“very poor”) instead of “severe.”
Practice MCQ
Q. Consider the following statements regarding air quality monitoring and management in India:
- The SAFAR (System of Air Quality and Weather Forecasting And Research) system was developed by the Indian Institute of Tropical Meteorology (IITM), Pune, under the Ministry of Earth Sciences.
- A shift in surface wind direction from north-westerly to easterly over the Delhi-NCR region during November typically increases the transport of stubble-burning smoke from Punjab into the capital.
Which of the statements given above is/are correct?
(a) 1 only (b) 2 only (c) Both 1 and 2 (d) Neither 1 nor 2
Answer: (a) 1 only
Hint: Statement 1 is correct; SAFAR is an MoES initiative developed by IITM Pune. Statement 2 is incorrect because Punjab and Haryana lie to the north-west of Delhi; therefore, north-westerly winds bring farm smoke into the capital, whereas a shift to easterly winds blocks and pushes that smoke away.
Hint: Statement 1 is correct; SAFAR is an MoES initiative developed by IITM Pune. Statement 2 is incorrect because Punjab and Haryana lie to the north-west of Delhi; therefore, north-westerly winds bring farm smoke into the capital, whereas a shift to easterly winds blocks and pushes that smoke away.
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