Clear sky in Delhi even as air quality remains in ‘very poor’ category
Delhi is likely to have a clear sky on Wednesday with mist in the morning, India Meteorological Department (IMD) said even as the air quality remained in the “very poor” category a day before Diwali. The minimum temperature on Wednesday was likely to be 14 and maximum 30 degrees Celsius. On Tuesday, the minimum temperature was 14.5 and the maximum 29.6 degrees Celsius, a notch below normal.
The IMD said mainly clear sky is also expected on Thursday which will change to partly overcast weather for at least four days from Friday.
According to the Central Pollution Control Board, the hourly Air Quality Index (AQI) at 8 am was 302 on Wednesday. On Tuesday, the average 24-hour AQI was 303 in the “very poor” category.
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”.
On Tuesday, the Union earth science ministry’s System of Air Quality and Weather Forecasting And Research (Safar) said the overall air quality of Delhi was in the lower end of the “very poor” category. The quality was expected to improve but remain in the upper side of the “poor” range until Wednesday. “...stubble related emissions will remain marginal (<10%) in spite of higher fire count due to unfavourable wind direction. The share of stubble burning emissions is just 6%. The stubble burning induced impact in AQI is expected to increase significantly from 4th November onwards due to transport-level winds reaching Delhi from North-Westerly where large stubble burning hot spots are expected.”
Safar said the air quality on Diwali (Thursday) will also depend on the extent of observance of the firecracker ban. “Under zero firecracker emission scenario, the level of PM2.5 is predicted to be at the in the upper end of very poor during 4-6th November. However, even if we consider 50% of additional firecracker related emissions of 2019, then AQI is predicted to degrade to the Severe category from 4th November night onwards and will remain severe until 5th November,” it said. “It is predicted to improve slightly on 6th Nov but will fluctuate between High-end of Very Poor to the Severe range. This is mainly due to the coincidence of all critical factors with a peak PM2.5 surpassing 300 ug/m3 on 5th November.”
The stubble fire share in Delhi’s PM2.5 is expected to be between 20-40% from November 4 to 6 if its counts are assumed to be similar to last year.