Delhi’s air quality deteriorated to the poor category early on Wednesday, with the Air Quality Index (AQI) reaching 227 at 7.05 am, marking the Capital’s first poor air quality reading of the season, according to official data.
The Central Pollution Control Board’s (CPCB) hourly readings showed that the AQI climbed from 179 in Tuesday’s 4 pm bulletin to 227 by 7 am on Wednesday, an increase of 48 points. The index crossed the threshold of 200 for the poor category at 2 am and remained above it in every subsequent hourly reading.
The deterioration followed Dussehra celebrations on Tuesday evening, when effigies were burnt and firecrackers were set off across several parts of the city. Emissions from these activities added to pollution from the ongoing Durga Puja festivities.
Several monitoring stations report poor air quality
Data from 56 of Delhi’s 59 air quality monitoring stations showed that two stations, Jahangirpuri and Pusa, recorded very poor air quality, with AQI readings of 308 and 314, respectively. Sixteen stations, including Anand Vihar, continued to report moderate air quality.
The CPCB classifies AQI readings between 0 and 50 as good, 51 and 100 as satisfactory, 101 and 200 as moderate, 201 and 300 as poor, 301 and 400 as very poor, and 401 and 500 as severe.
Delhi’s air quality had remained in the moderate category for most of October, apart from brief improvements on October 12 and 16 following rainfall. The AQI was recorded at 187 on October 18, 139 on October 19 and 179 on October 20.
The Capital last recorded poor air quality on July 12 and 13, when the AQI stood at 261 and 246, respectively.
Farm fires continue in Punjab and Haryana
The rise in pollution also comes amid ongoing stubble burning in neighbouring Punjab and Haryana. NASA’s satellite detected 182 farm fires across the two states in the three days leading up to October 20. Since October 1, the satellite has counted 397 fires, compared with 523 over the corresponding period last season.
However, the figures may substantially understate the actual number of fires. Satellite passes take place at around 1.30 pm, while much of the stubble burning now occurs later in the day. As a result, a lower satellite count does not necessarily indicate a reduction in farm fires.
Falling temperatures add to pollution concerns
The deterioration in Delhi’s air quality has also been attributed to falling temperatures and changes in wind speed. These conditions can limit the dispersion of pollutants, allowing them to accumulate in the atmosphere and worsening air quality.