Bans relaxed, air ‘severe’ again; Delhi hopes for wind, rain relief

NEW DELHI: The national capital’s air quality is back in the ‘severe’ category and the region’s main pollution control and prevention agency’s response is to look to the skies, literally, in anticipation that winds and late-night rain will help mitigate the situation.

The jump back into ‘severe’ – the air quality index, or AQI, on Tuesday was at 409 – also highlighted the rashness of the Environmental Pollution (Prevention and Control) Authority, or EPCA, which on Monday relaxed bans on construction, entry of trucks, and the operation of industries using coal and biomass on the technicality that AQI dipped into the ‘very poor’ zone. On Monday, AQI was at 399, a point below the ‘severe’ level of 400 (see box).

EPCA’S Big Idea on Monday was to suggest imposing a ban on all petrol and diesel vehicles, including private ones, which, if implemented, would have given Delhi the distinction of being the first Capital of a major economy to ban a large majority of its private vehicles. Fortunately, there was no follow-up on this bright idea on Tuesday, although there could be some developments on this front on Wednesday when the Central Pollution Control Board (CPCB)’S task force meets.

Unfortunately, there was no other follow-up as well.

Government agencies forecast that AQI would improve and enter the very poor category on Tuesday. Scientists from government agencies blamed the slight rain on Monday morning for the deterioration.

“While we expected that the rain would help bring down pollution, it was so sporadic and scarce that it pushed up the moisture levels. The high relative humidity increased the holding capacity of the air and the pollutants got trapped. The low wind speed aggravated the conditions,” said a scientist from Safar, which is a Union governmentrun pollution forecasting wing.

It was based on the predictions of the government’s pollution forecasting agencies that CPCB recommended that the ban on construction, entry of trucks and industries using coal and boil fuel could be relaxed. On Monday, the Supreme Court-appointed EPCA relaxed the bans.

On Tuesday, the forecasting agencies including Safar and the Indian Institute of Tropical Meteorology, which runs the national capital’s early warning system for pollution, predicted that pollution levels could dip from November 15 as wind speed is likely to increase. Delhi needs a wind speed of at least 10km per hour to disperse pollutants .

“The wind speed which was less than 5km per hour on Tuesday is expected to pick up from Thursday. It is expected to reach a speed of 10-20 km per hour,” said a senior official of the India Meteorological Department who asked not to be named.

Interestingly, scientists blamed the current bout of pollution on local activities and not stubble burning in parts of Punjab and Haryana. The upperlevel winds -- on which pollutants from stubble burning are borne -is now coming mainly from the south-easterly direction, which means it isn’t bringing in any pollutants from Haryana and Punjab. The scientists blamed construction activities, vehicles and road dust, with the situation exacerbated by low wind speed and high relative humidity. That means EPCA’S Monday decisions may have directly contributed to Tuesday’s problems.

At 9pm on Tuesday, levels of particulate matter in the entire National Capital Region were still hovering above the ‘severe’ levels. However, following a drizzle around 10.30pm, and winds picking up speed, the levels of particulate matter gradually started to come down as the day ended.