“Sudden unforeseeable low winds” were the key cause of the noxious air quality that gripped the Delhi National Capital Region following Deepavali, according to an expert sub-committee that is tasked with recommending pollution control measures under the Graded Response Action Plan (GRAP) with no acknowledgement of the role of crackers or stubble burning.
A day after Deepavali, the Air Quality Index (AQI) in Delhi, Faridabad, Noida, Gurugram and Ghaziabad shot to over 450 or at the highest level of pollution severity called ‘severe.’ Though there was a ban on the use of crackers in all these regions, these norms were brazenly flouted and a change in wind direction increased the load of pollutants from Punjab and Haryana from stubble burning.
Ignores report
The committee chose to ignore a scientific report from the Central Pollution Control Board (CPCB) and the India Meteorological Department (IMD) themselves on November 5, that explicitly holds “... crackers, biomass burning and unfavourable weather conditions that brought AQI to severe.” Minutes of all these meetings appear on the CPCB website.
This report — and two others on November 3 and 4 — also say that wind speeds were expected to be less than 10 kmph, or at the level, that makes it hard for airborne pollutants to be flushed out. There was thus no “sudden drop” in wind speeds as the committee notes.
These scientific reports on wind and pollution forecast are prepared daily.
The expert committee is led by the Member-Secretary, CPCB, and has technical experts from the IMD as well as representatives from pollution control authorities in Delhi, Haryana, Punjab, Uttar Pradesh and Rajasthan. This committee met on November 5, a day after Deepavali to take stock of the noxious situation in the National Capital region that saw air quality dip to ‘severe’ levels.
“... The AQI was predicted to be within very poor category, however, as informed by the IMD, there were sudden unforeseeable low winds that resulted in Severe Air Quality. V.K. Soni, IMD, confirmed that it might be attributed to sudden calming of winds, which could not be captured by the model,” say the minutes of the sub-committee meeting on November 5.
Before its meeting on November 5, the expert sub-committee met on November 3, a day before Deepavali. Dr. Soni, meteorologist at the IMD and part of the committee, ruled out the possibility of air quality ever reaching the ‘severe’ category. “Even with higher emissions, model predictions do not indicate air quality reaching to ‘severe’ category ... in view of the above, the sub-committee suggests no additional measures except strict implementation of order issued earlier on October 18 and 28.” These are routine orders that State pollution control boards must implement assuming that air quality remains in the ‘poor’ and ‘very poor’ categories.
GRAP provisions
According to the provisions of the GRAP, ‘severe’ air quality can prompt the sub-committee to order a halt on inbound trucks to Delhi or odd-even restrictions on cars as well as closure of brick kilns, stone crushers. However, following its assessment, the sub-committee has only recommended that government and private offices and other establishments reduce vehicle usage by at least 30% (by working from home, car pooling, and optimising their field activities, etc.) and pollution control implementing agencies to step up their efforts.
The Commission for Air Quality Management, that has been set up by an Act of Parliament to oversee the implementation of pollution control had earlier this week claimed that instances of stubble burning during September to November first week, in Punjab and Haryana, was half that of previous years. However, the CPCB’s reports show that stubble burning on November 3, 4, 5 were not significantly lower — and that in Haryana was higher — than last year. A change in the direction of wind from easterly to northwesterly on Deepavali brought much of the carbon towards Delhi NCR and increased the contribution of biomass burning from 5% in the days leading up to Deepavali to as much as 20%, according to the CPCB/IMD’s scientific reports.
Wind speeds are expected to pick up over the weekend and improve air quality, according to the IMD’s latest assessments.
