New Delhi: Delhi’s air quality witnessed a sudden dip on October 21, prompting authorities to put in place Stage I of the Graded Response Action Plan (a series of emergency anti-air pollution measures) in the national capital. “The Air Quality lndex (AQI) of Delhi which was observed 179 (‘Moderate’ category) on 20.10.2026, has exhibited a sharp rise with AQI of 244 at 02:00 PM on 21.10.2026 (‘Poor’ category). Further, the forecast by IMD/IITM has also predicted AQI to remain in ‘Poor’ category in [sic] coming days,” the statement released by R.K. Agarwal, Director (Technical) and Member Convenor of the Sub-Committee on the Graded Response Action Plan (GRAP), said. As a result, the Sub-Committee has ordered all concerned authorities including the Delhi Development Authority and National Highway Authority of India to invoke all actions under Stage-I (‘Poor’ Air Quality) of the extant GRAP in the entire NCR, with immediate effect. The sub-committee on the Action Plan under the Commission for Air Quality Management in the National Capital Region and Adjoining Areas met on October 21 and reviewed the air quality scenario in the region, as well as the forecasts provided by the India Meteorological Department and Indian Institute of Tropical Meteorology.The GRAP, overseen by the CAQM, is classified into four different stages of bad air quality in Delhi. Stage – I actions are to be in place in case of ‘Poor’ air quality (AQI 201 – 300), Stage – II for ‘Very Poor’ air quality (AQI 301-400), Stage – III for ‘Severe’ air quality (AQI 401-450) and Stage – IV for ‘Severe +’ (AQI >450).Measures under Stage I include ensuring that no open burning occurs in landfills and dump sites, carry out regular and mechanised sweeping and water sprinkling on roads to ensure lesser dust in the air as well as implement other dust-suppression measures such as anti-smog guns, restrictions on construction and development activities on specific projects that are larger than 500 sq metres and more.