Rain brings relief from heat in Delhi, GRAP-2 measures lifted amid ‘poor’ AQI

To be sure, air quality in the region starts to improve from late February and early March as temperatures rise, making it easier for pollutants to disperse.

Patchy showers, overcast skies, and gusty winds brought temporary relief to the Capital on Wednesday as mercury dropped sharply after two days of over 30°C-temperature. The Commission for Air Quality Management (CAQM) also lifted measures under stage-2 of the Graded Response Action Plan (Grap) though there was no significant improvement in air quality.

Weather forecasts show this respite is temporary, with the maximum set to rise again from Thursday onwards. (Vipin Kumar/HT PHOTO)

The 24-hour average air quality index (AQI) stood at 214 (poor), according to the 4pm bulletin. It was the fifth continuous day that the AQI was in the “poor” category, just a few points lower than Tuesday’s average AQI of 249.

The CAQM said it was lifting restrictions under Grap stage-2 since “as per the dynamic model and forecasts for meteorological conditions and air quality index made available by both the India Meteorological Department (IMD) and Indian Institute of Tropical Meteorology (IITM), the average AQI of Delhi is likely to remain in ‘poor’ to ‘moderate’ category in the coming days.”

This marked an end to restrictions on the entry of non-BS-6, EV or CNG-compliant interstate buses into Delhi as well as increased parking fees and restricted use of diesel generator sets in Delhi-NCR. Stage-2 applies once AQI crosses 300 (very poor) and is forecast to stay above the threshold. The measures had been in place since last year.

To be sure, air quality in the region starts to improve from late February and early March as temperatures rise, making it easier for pollutants to disperse.

With this, Delhi is back under stage-1 restrictions, which, given the city’s poor air quality record, essentially apply all-year round. This includes sprinkling of water and mechanised sweeping of roads, ensuring regular lifting of waste and strict enforcement of pollution under control (PUC) norms, among others.

Rain and strong winds of up to 40km per hour, in addition to overcast skies, led to temperature dropping nearly 10 degrees from a day earlier and registering at three degrees lower than what is normal for this time of the year. On Wednesday, the maximum was 21.1°C, compared to 30.9°C on Tuesday — seven degrees above what is normal for this time of the year. It was 31.6°C on Monday— the first time temperatures crossed 30-degree mark this year and the earliest they have crossed this threshold in February in five years.

Overcast skies led Delhi’s minimum temperature to rise to 15.8°C — five degrees above normal. On Tuesday, the minimum was recorded at 12.4°C.

According to IMD data, the Safdarjung station logged 0.2mm of rainfall till 8:30 am; Lodhi Road 0.2mm, Palam 0.9mm; Ayanagar 0.5mm, while the Ridge station saw ‘trace’ rainfall. Between 8:30am and 5:30pm, Safdarjung logged another 0.3mm, Palam 1.2mm, Lodhi Road 0.5mm and Ayanagar 0.5mm.

However, weather forecasts show this respite from early February heat is temporary, with the maximum set to rise again from Thursday onwards as the impact of this prevailing western disturbance fades away.

“Some scattered very light rain was recorded in the city. Since the western disturbance was feeble, it will not do much in terms of impacting the temperature, which will again start to rise from Thursday and Friday,” said an IMD official.

The maximum is expected to hover between 26-28°C on Thursday, before gradually rising again and touching 31°C by Sunday. It is further forecast to touch 32°C by Monday and Tuesday, making for a warm end to the month.

IMD forecasts show the minimum is likely to hover between 12-14°C from now till the weekend, keeping nights warm too.