New Delhi: The Centre today ordered a ban on non-essential construction work and movement of BS-III petrol and BS-IV diesel four-wheelers in Delhi-NCR amid worsening air quality in the region.

Unfavourable meteorological conditions including fog and haze with low wind speed are the major causes for a sudden spike in Delhi's daily average air quality index (AQI), the Commission for Air Quality Management (CAQM), a statutory body responsible for formulating strategies to combat pollution in the region, said in an order.

Delhi's overall AQI is steadily rising since this morning. It stood at 397 at 10 am and 409 at 4 pm.

Re-invoking curbs under Stage-III of the Graded Response Action Plan (GRAP), the CAQM ordered a ban on non-essential construction work, stone crushing, and mining in Delhi-NCR.

Construction work related to national security or defense, projects of national importance, healthcare, railways, metro rail, airports, interstate bus terminals, highways, roads, flyovers, overbridges, power transmission, pipelines, sanitation, and water supply are exempted from the ban.

Under Stage-III, restrictions are also imposed on the operation of BS-III petrol and BS-IV diesel four-wheelers in Delhi, Gurugram, Faridabad, Ghaziabad, and Gautam Budh Nagar.

GRAP is the Centre's air pollution control plan implemented in the region during the winter season.

GRAP categorises actions into four stages: Stage I - 'Poor' (AQI 201-300); Stage II - 'Very Poor' (AQI 301-400); Stage III - 'Severe' (AQI 401-450); and Stage IV - 'Severe Plus' (AQI>450).