The air quality in Delhi worsened on Sunday and continued to remain in the poor category for the fourth consecutive day as the index reading touched the 245 mark, PTI reported. It is expected to deteriorate to “very poor”.

An Air Quality Index reading from zero to 50 is considered to be good, 51-100 is satisfactory, 101-200 is considered to be moderate, a reading between 201 to 300 is poor, 301-400 is considered “very poor” and air quality between 401-500 is severe.

According to the Central Pollution Control Board, Haryana’s Alipur Khalsa and Panipat areas have already recorded air quality index reading of more than 300, placing them in the “very poor” category.

On Saturday, Delhi Chief Minister Arvind Kejriwal had blamed stubble burning for the rise in pollution. “The smoke from crop stubble burning in neighbouring states has started reaching Delhi and our air quality has started deteriorating from good to moderate to poor to very poor,” he said. Kejriwal has urged the Haryana and Punjab governments to take steps to curb air pollution.

Government-run monitoring agency System of Air Quality and Weather Forecasting and Research, or SAFAR, has said smoke from stubble burning will make up 6% of the city’s pollution by October 15.

“The surface wind speed continues to be slow and variable with predominant direction from the west,” India Today quoted SAFAR as saying. “Under these conditions, the air quality is predicted to deteriorate to the middle of the poor category by tomorrow. Further deterioration of the AQI is expected by October 14.”

Delhi’s air quality slipped to the “poor category” for the first time this season on Thursday, days after the city breathed the cleanest air in five years. Data from the Central Pollution Control Board on Wednesday had showed the Air Quality Index to be 173, compared to 326 at the same time last year.

On September 25, reports said there had been at least 117 incidents of stubble burning in Punjab in two days since the start of the harvesting season.

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