Mercury climbs to 42°C as dry, dusty winds bring Delhi AQI down to ‘very poor’
IMD said Delhi’s maximum should drop marginally around May 12 due to a western disturbance, which may bring light rain and overcast skies
Clear skies for the past few days raised Delhi’s maximum temperature to 42 degrees Celsius (°C) on Tuesday, three degrees above normal and the highest so far this year, and the dry conditions brought dusty winds to the city, resulting in a drop in air quality to the “very poor” zone.
The Delhi-National Capital Region (NCR) saw dry, dust-raising winds of 10-15 km/hr throughout Tuesday. According to the India Meteorological Department (IMD), respite is unlikely over the next three days, with the maximum temperature to remain above 41°C, and similar dusty conditions expected to prevail across the city.
“At 42°C, this is the highest maximum so far for Delhi this year. No heatwave conditions have been recorded at any station. We saw consistent winds of 10-15 km/hr during the day. Since we have not seen any significant rain spell in the last few weeks, the topsoil is dry and these winds are raising local dust. Similar conditions may prevail on Wednesday, too. Easterly winds are now beginning to blow towards Delhi, which tends to bring a little moisture. There are chances the maximum may drop to 41°C on Wednesday and Thursday, but there is no significant respite,” said Kuldeep Srivastava, scientist at IMD.
In terms of minimum temperature, Delhi recorded a low of 24.2°C, which was a degree below normal.
No heatwave
Though the Safdarjung observatory is considered representative of Delhi’s weather, other locations, particularly in the outer parts of Delhi, are even warmer. The highest maximum on Tuesday was 43.9°C at Najafgarh, and 43.1°C at Jafarpur, IMD data showed. The highest maximum recorded at any weather station so far this year was 44°C at the Sports Complex station (Akshardham) on May 5.
Delhi is yet to record a heatwave day so far this year. IMD classifies it as a “heatwave” when the maximum is more than 40°C, while also being 4.5 degrees or more above normal. The highest maximum recorded in May last year was 43.7°C on May 23. In 2022, it was 45.6°C on May 16. In 2021, it was 41.6 (May 5) and in 2020, it touched 46.0°C on May 27.
Light rain on weekend
IMD said Delhi’s maximum should drop marginally around May 12 due to a western disturbance, which may bring light rain and overcast skies. “We may see cloudiness, light rain and gusty winds of 25-35 km/hr on May 11 and May 12. This may bring down the maximum to around 40°C,” Srivastava said.
Forecasts show the minimum temperature is likely to hover between 24°C and 25°C till the end of the week.
High dust pollution
After four consecutive “poor” air quality days, Delhi’s air quality deteriorated to the “very poor” category on Tuesday. The Central Pollution Control Board’s national bulletin, released every day, showed the 24-hour average air quality index (AQI) for Delhi was recorded at 302 (very poor) — a rise from Monday’s average AQI of 247 (poor). The last time Delhi’s AQI was in the “very poor” zone was on February 14 when it was recorded at 341, data showed.
Forecasts by the Centre’s Early Warning System (EWS) showed that AQI was likely to stay “very poor” on Wednesday as well. “The air quality is likely to remain in the ‘very poor’ zone on Wednesday and may improve to the ‘poor’ category on Thursday and Friday,” EWS said in its daily bulletin.
The Commission for Air Quality Management (CAQM) in NCR held an emergency meeting on Wednesday, in the wake of the deteriorating air quality and decided not to impose the emergency-level Graded Response Action Plan (Grap). However, it has asked all agencies in NCR to intensify actions to control dust in the region.
“The average AQI of Delhi has touched 300 due to highly unfavourable meteorological conditions. Particulate matter load over the region has increased due to rapid changes in wind direction and speeds due to high convection rate and absolutely dry conditions leading to continued suspension of dust and may not be attributed to any specific local sector. All agencies concerned have been asked to intensify actions for abatement of dust arising from various C&D activities, linear projects and from roads, pathways or right of ways and open areas through various dust abatement measures prescribed by CAQM,” it said in a statement on Wednesday.
Dust consists of coarser particles, which leads to a spike in PM 10 concentration. Last May, Delhi had seen one “very poor” air day, on May 17, when AQI rose to 336 that day, again due to dust-raising winds.
Though the overall average was “very poor”, CPCB data showed two stations, Anand Vihar and Shadipur crossed the 400 mark. CPCB classifies an AQI between 0-50 as “good”, between 51 and 100 as “satisfactory”, between 101 and 200 as “moderate”, between 201 and 300 as “poor”, between 301 and 400 as “very poor”, and over 400 as “severe”.
Anumita Roychowdhury, executive director, of research and advocacy, at the Centre for Science and Environment, said PM 10 was the prominent pollutant at present, a reflection of high dust pollution. “This is common for the summer months when there is high dust pollution impacting the city. This shows the need to monitor dust-generating activities at construction sites and ensure effective mitigation measures are in place. A summer action plan is needed to act on all local summer sources of pollution,” she said.