Delhi air quality slips into severe zone; temperatures continue to fall in NCR

The Capital’s air quality plunged sharply into the deep red zone on Friday — the third time this month — and clocked a 24-hour air quality index of 409 (severe) at 4pm, according to the Central Pollution Control Bureau’s (CPCB) national bulletin.

The drop was by 77 points compared to the “very poor” reading of 332 on Thursday. Despite the deterioration, the Commission for Air Quality Management (CAQM) refrained from invoking Stage 3 of the Graded Response Action Plan (Grap) arguing that forecasts showed relief from bad air over the weekend.

The deterioration belied predictions by the early warning air quality forecasting system, which on Thursday said the air quality was unlikely to dip into the “severe” zone for the rest of the month.

The two other days when AQI was “severe” this month were January 24 (409) and January 14 (447). It has been “very poor” — between 300 and 400 for 22 days this month — and “poor” — between 200 and 300 on one day.

CAQM said the deterioration was down to a combination of factors, including low temperature and fog.

“As per the assessment of the IMD and the Indian Institute of Tropical Meteorology (IITM), the dispersion of air pollutants has been low because of the dip in temperature, foggy conditions and local sources, due to which a spurt in the average AQI of Delhi has been witnessed. The CAQM sub-committee, however, while comprehensively reviewing the air quality scenario and relevant aspects, noted that as per the air quality forecasts by IMD and IITM, Delhi’s average AQI is likely to improve from Friday itself and is expected to be in the ‘very poor’ category in the coming days,” said CAQM in a statement, explaining its decision to not invoke Stage 3 of Grap.

Stage 3 involves a ban on non-essential construction activities and the use of BS III petrol and BS IV diesel four-wheelers in Delhi-NCR, along with a complete ban on diesel generators. The use of coal and firewood in certain industries is also prohibited.

Delhi recorded a minimum temperature of 4.7 degrees Celsius (°C) on Friday, which was four degrees below normal. It was 4.8°C a day earlier. This was Delhi’s lowest minimum on Republic Day in the last three years and the second lowest in the last decade, behind 2021, when it was 2.1°C, India Meteorological Department (IMD) data showed.

The IMD has forecast the minimum to hover around 5°C on Saturday, before rising to 6°C on Sunday and to 8°C by Monday, as a western disturbance approaches northern India. “We will gradually see a rise in temperature in the next few days. Shallow to moderate fog is expected in the early hours of the day, with the fog intensity to gradually reduce,” said an IMD official.

Parts of the city recorded dense fog on Friday, but the impact was limited to a few areas. Dense fog prevailed for around three hours — between 5.30 am and 8.30am when visibility was down to 100 metres at Palam. It was moderate at Safdarjung, and the lowest visibility was recorded at 300 metres during this period.

IMD said that “moderate” fog was recorded at 9am, which improved to “shallow” by 10am at most places, with sunlight breaking through.

The fog delayed around 25 flights at Delhi’s Indira Gandhi International (IGI) airport and at least 34 trains were delayed by over an hour.

The city’s maximum stood at 20.6°C, which was a degree below normal. It was 20.5°C on Thursday. The maximum is forecast to rise further and will likely hover between 21°C to 22°C over the next three days, the Met department added.

The maximum temperature at Gurugram and Noida was also recorded at 20.6°C. However, the minimum at Gurugram was 3.5°C while at Noida it was 5.6°C.