Air quality plummets into ‘severe’ zone

Air quality in the city deteriorated to the ‘severe’ category on Thursday for the first time this season, with a reading of 443 on the Central Pollution Control

Air quality in the city deteriorated to the ‘severe’ category on Thursday for the first time this season, with a reading of 443 on the Central Pollution Control Board’s air quality index (AQI) bulletin.

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This is significantly up from Wednesday’s AQI reading of 296, which indicated ‘poor’ air. Officials and experts attributed this sudden increase in pollution to a shift in meteorological conditions, which resulted in extremely low wind speed after two days of favourable wind patterns, and a steep drop in minimum temperature while stubble burning continued in parts of Punjab.

The early air quality warning system for Delhi-NCR stated, “Unusually high farm fire counts (approx..5000), maximum of this season were observed over Punjab on 04.11.2020 which is affecting AQI over Delhi/NCR and parts of Northwest India.”

Vijay Soni, scientist, air quality division, India Meteorological Department (IMD), said, “Smog-like conditions have developed because of air pollution, low wind speed and subsidence of cold air over Delhi-NCR. As a result, dispersal of pollutants is not possible.”

However, forecasts by the Indian Institute for Tropical Meteorology, and the CPCB’s central control room for air quality management indicate that the situation may see a slight improvement over the next few days.

As per the early air quality warning system, “The AQI is likely to improve owing to higher windspeed and better ventilation. The AQI is likely to reach in higher end of Very Poor category on 06.11.2020. The air quality is likely to remain in Very Poor category on 07.11.2020 (sic).”

The CPCB, meanwhile, has forecast an AQI of 305 for Gurugram on Friday, which may further improve to the upper-end of the ‘poor’ category over the weekend, owing to dispersal from favourable northwest winds.

On Thursday, the city recorded a minimum temperature of 11 degrees Celsius, down from 14.1 degrees Celsius the previous day. The maximum temperature was recorded at 29.9 degrees Celsius, two above Wednesday’s 27.5 degree Celsius. The minimum temperature is expected to hover around 11 degrees Celsius on Friday, while the maximum temperature is expected to be around 30 degrees Celsius.

Clear skies during the day with fog and mist in the morning are expected to prevail this week, as per the IMD’s weekly forecast, which also predicts wind speeds between 5 to 15kmph over Delhi-NCR on Friday.

Thursday’s rapid deterioration of air quality also prompted the CPCB’s task force on Graded Response Action Plan (Grap) to meet. In the minutes of the meeting, which were shared with Hindustan Times by the Haryana State Pollution Control Board’s regional office in Gurugram, the task force has said, “Government and private offices and other establishments are advised to reduce vehicle usage by at least 30% (by working from home, car-pooling, and optimizing their field activities.”

Gurugram was yet to issue an advisory to this effect on Thursday evening. The minutes also state that air quality is likely to improve from Thursday evening due to increased wind speed, and will likely remain ‘very poor’ over the next two days.

However, in case the air quality remains ‘severe’ for a period of 48 hours (or if PM2.5 remains above 250ug/m3, or if PM10 remains above 430ug/m3 for the same time), three broad Grap measures are rolled out. These include increasing sweeping and dust sprinkling along roads where dust pollution is an issue, shutting down brick kilns in and around Delhi-NCR, and restricting operations of coal-based power plants. When air quality surpasses this threshold and enters the ‘severe plus’ category, construction work is to be halted, entry of trucks into Delhi-NCR cities is curbed. The odd-even vehicle rationing scheme is also recommended to be implemented under the Grap, in ‘severe plus’ situations.