Delhi’s AQI plunges to worst levels since February 18
Scientists attributed the deterioration of the city’s AQI to a dip in wind speed, with dust particles which were hanging over Delhi gradually settling down.
A day after strong westerly winds brought dust from Rajasthan to the Capital, shrouding the city in a sepia-toned haze, Delhi pollution levels on Wednesday plunged to the “very poor” zone. According to the Central Pollution Control Board (CPCB) 24-hour national bulletin, released at 4pm, Delhi’s Air Quality Index (AQI) on Wednesday was 336 — the worst that Delhi’s pollution levels have been since February 18, when the AQI reading was 371.
In comparison, Delhi’s AQI on Tuesday was 254 (poor).
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Scientists attributed the deterioration of the city’s AQI to a dip in wind speed, with dust particles which were hanging over Delhi gradually settling down. “The average wind speed on Wednesday was 8-10 kmph, and while the wind was northwesterly, there was limited dust intrusion from Rajasthan,” said Kuldeep Srivastava, scientist at India Meteorological Department (IMD).
On Tuesday, however, wind speeds had reached 80kmph, with visibility dropping to as low as 900m in parts.
At 8am on Wednesday, when Delhi’s AQI was at its peak at 397, at least 20 out of the 38 functional ambient air quality monitoring stations logged AQIs in the severe category — the highest average AQI was 474 at Mundka, followed by a reading of 460 at both Rohini and Bawana.
On Tuesday, Delhi’s average PM10 concentration had touched 941 micrograms per cubic metre (µg/m3) at 10 am, before it dipped to around 300µg/m3 at 7 pm. CPCB data shows there was another spike in PM10 levels at midnight, when the PM10 concentration was recorded at 614µg/m3, before a gradual dip to 166µg/m3 micrograms at 1 pm on Wednesday.
PM 10 – consisting of coarser dust particles currently plaguing the Capital — was the lead pollutant at all the weather stations.
To be sure, the safe standard for PM10 is 100µg/m3.
VK Soni, scientist at IMD and part of the Commission for Air Quality Management (CAQM) in NCR, said the body was keeping a close tab on air quality in the region, adding that Delhi’s average AQI was high on Wednesday largely due to the high readings recorded on Tuesday. “Since the AQI considers the last 24 hours, it was still fairly high in the morning. Real-time data shows that after midnight, we began to see a dip in pollution levels and as the day progressed, the dust settled down,” he said.
Experts said dust particles can irritate the lungs, trigger respiratory problems, and exacerbate existing conditions such as asthma, bronchitis, and allergies.
“People suffering from respiratory diseases such as bronchitis, bronchial asthma and chronic obstructive pulmonary disease are at a greater risk due to dust pollution. It may worsen their condition and trigger attacks,” said Dr Jugal Kishore, head of the medicine department of the Safdarjung Hospital.
Dusty conditions also aggravate rhinitis, allergy and irritation of the eyes, he said, adding that people should try and remain indoors till the air quality improves and cover their nose and mouth with a wet cloth.
The Capital on Wednesday also saw overcast skies, with some places in north Delhi receiving trace rain in the early hours of the day. IMD said Delhi is likely to see similar weather on Thursday, with chances of very light rain in parts of the National Capital Region (NCR).
“We saw cloudiness and rain in north Delhi, with similar drizzle expected late on Wednesday night and during the day on Thursday,” said Srivastava, adding that the rain was due to an active western disturbance currently influencing Jammu and Kashmir.
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“The western disturbance’s impact will remain till Thursday, with clear skies once again expected after that,” he said.
Forecast by the Early Warning System (EWS) for Delhi, which is used by CAQM to take decisions under the Graded Response Action Plan (Grap), shows Delhi’s AQI is likely to be in the “poor” zone between May 18 and 20. In the subsequent six days, it is likely to be between “poor” and “moderate”.
The 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.