After nearly 10 days, Delhi's air quality deteriorated on Monday to the "very poor" category and is likely to worsen in the next two days due to slow winds and low ventilation, government agencies said.
Stubble burning, which accounted for 12 percent of Delhi's PM2.5 pollution on Sunday, contributed six percent on Monday.
According to the Central Pollution Control Board (CPCB) mobile app, SAMEER, the city's air quality index (AQI) was recorded at 281 on Monday morning and deteriorated to 302 in the evening. It was 274 on Sunday.
It was 251 on Saturday, 296 on Friday, 283 on Thursday and 211 on Wednesday.
The capital's AQI was in the 'severe' category on November 15, a day after Diwali, but later improved and remained in either 'poor' or 'moderate' category until Sunday.
An AQI between zero and 50 is considered "good", 51 and 100 "satisfactory", 101 and 200 "moderate", 201 and 300 "poor", 301 and 400 "very poor", and 401 and 500 "severe".
However, according to the Ministry of Earth Sciences' air quality monitor, SAFAR, stubble burning count has significantly decreased to 149.
Effective stubble fire counts with sufficient potential estimated from SAFAR-multi-satellite products have significantly decreased and are around 149.
However, stubble burning share in PM2.5 in Delhi's air is estimated as six percent for today, mainly because calm wind is likely to hold intruded mass for a day, SAFAR said.
It said that winds are expected to slow down with low ventilation.
The AQI is likely to deteriorate towards the high end of Very Poor by tomorrow and likely stay at the high end of Very Poor on November 25 and may reach Severe in few locations for short period, it said.
'High end' means closer to the next worse category.
This scenario is valid if prevailing low fire counts remain but if counts increased then it may further deteriorate.
As many as 649 farm fire counts were observed over Punjab, Haryana and adjoining regions on Saturday, according to SAFAR.
Stubble burning accounted for 13 percent of Delhi's PM2.5 pollution on Saturday, 15 percent on Friday, 20 percent on Thursday and eight percent on Wednesday.
According to India Meteorological Department, a cold wave gripped Delhi on Monday as the minimum temperature dropped to 6.3 degrees Celsius, five notches below normal and the lowest in the month of November since 2003.
The maximum temperature was recorded at 26 degrees Celsius. The humidity oscillated between 59 percent and 90 percent.
On Sunday, the national capital had recorded a minimum of 6.9 degrees Celsius and a maximum of 24.2 degrees Celsius, the lowest daytime temperature so far this month.
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