The air quality in the national capital remains critically poor following Deepavali, despite the implementation of GRAP stage IV measures, active Supreme Court intervention, and temporary measures by the Delhi government. Much of the blame is being directed at farm fires in neighboring states, where farmers burn paddy stubble to prepare for the wheat-sowing season. Although these fires are not the sole cause of Delhi’s deteriorating air quality, the controversy over how they are measured highlights their significant attention.

How are the fires monitored?

Farmers in Punjab and Haryana grow rice during the kharif season, harvesting it in November, relying on monsoon rains to meet the crop's high water demand. After harvest, they clear the leftover stubble to prepare for the next crop. Burning the stubble is often the quickest and cheapest method, but during this season, winds carry the resulting particulate matter to Delhi, worsening air quality.

Given the scale of the fires, satellite data is considered the most efficient way to monitor them. The Indian government currently uses data from NASA’s Aqua and Suomi-NPP satellites.

• Aqua satellite: Launched in 2002, its Moderate Resolution Imaging Spectroradiometer (MODIS) tracks atmospheric changes.
• Suomi-NPP satellite: Launched in 2011, its Visible Infrared Imaging Radiometer Suite (VIIRS) serves as MODIS’s successor. Both are part of NASA’s Earth Observing System.

These satellites pass over locations twice daily—at 1:30 p.m. and 1:30 a.m. local time—capturing visible and infrared images. Their instruments can detect fires, smoke, and aerosols, which are critical for understanding the fires' impact on air pollution.

What is the controversy?

• On October 2, NASA scientist Hiren Jethva noted a 40% reduction in farm fires for 2023 and expressed optimism for a continued decline. Later, in October 2024, he observed the lowest fire counts in a decade but suggested that farmers might be burning stubble after the satellites' overpass times, requiring further verification.
• He backed this claim by comparing data from Aqua, Suomi-NPP, and South Korea’s GEO-KOMPSAT 2A satellite, which operates in geostationary orbit and provides near-continuous coverage. The visuals indicated increased smoke later in the day, aligning with suspicions of delayed stubble burning.
• Adding to the controversy, the CAQM (Commission for Air Quality Management) is accused of downplaying these activities. Internal documents and farmer testimonies suggest they were advised to burn stubble after the satellite overpasses to evade detection.
• While CAQM claims reduced fire incidents, conflicting data from Punjab's government and the Indian Agricultural Research Institute suggest an increase.

Government and Court Responses

The Supreme Court has criticized the CAQM for its inadequate efforts to address pollution from farm fires. The CAQM maintains that fire incidents in Punjab and Haryana have decreased significantly since 2020, though its methods have been questioned. It