SATV, Kathmandu, July. 13 - Barely days after successive monsoon showers gave Delhi its cleanest air in nearly three years, the national capital has seen its pollution levels spiking — owing to a dust storm from West Asia.

On Monday morning, the air quality deteriorated rapidly, inching towards the ‘Very Poor’ category.

On Sunday, Delhi’s daily average Air Quality Index (AQI) climbed to 261 (‘Poor’) — the first ‘Poor’ air day of this month. At 9 am on Monday, the city’s AQI touched 294.

Across the National Capital Region, Greater Noida recorded an AQI of 352 (‘Very Poor’), while Gurgaon stood at 271 and Noida at 261.

From ‘Good’ to ‘Poor’ in three days

The sharp deterioration comes less than a week after Delhi recorded its first ‘Good’ air day of the year.

On July 9, the city’s daily average AQI had dropped to 48, the lowest recorded this year and the cleanest air Delhi had witnessed since September 10, 2023. Back-to-back spells of monsoon rain had washed pollutants out of the atmosphere, keeping air quality in the ‘Good’ and ‘Satisfactory’ categories for several days.

The latest spike has effectively wiped out those gains, with the AQI jumping more than 200 points within three days.

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According to the Commission for Air Quality Management (CAQM), the sudden deterioration is being driven by a large-scale transboundary dust event rather than local pollution sources.

“The decline in air quality is attributed to long-range transboundary mineral dust transport, with a storm originating near Afghanistan, Iran and Pakistan moving towards north western India including Delhi, resulting in elevated atmospheric PM10 concentrations,” the commission said after a meeting of the Graded Response Action Plan (GRAP) Sub-Committee on Sunday.

The commission added that strong winds over the Indo-Gangetic Plain were carrying mineral dust into Delhi-NCR, leading to a sharp increase in Particulate Matter (PM) 10 levels across monitoring stations.

Dr Shashi Kant, senior scientist at the India Meteorological Department (IMD), said satellite imagery indicates that the dust-laiden wind is arising from South Pakistan and adjoining areas, resulting in transboundary dust transport into India.