Delhi NCR was covered with thick haze on Thursday after sudden winds and dust storms were witnessed in the capital city on Wednesday night. As a result, visibility was also plunged at many locations within Delhi, according to the Indian Meteorological Department (IMD).

The sudden winds of 30 to 40 km/h over the Palam area swept fine dust particles into the lower atmosphere. The capital city already has a lot of construction sites that add to its atmospheric dust pollution. A senior IMD official also stated that visibility fell from 4,500 m to 1,200 m in just two hours from 10 PM to 11:30 PM on Wednesday night.

Despite the sudden drop in visibility and heavy suspended dust present in the atmosphere, the IMD officials clarified that this phenomenon cannot be termed as a dust storm. According to IMD’s forecast, a light dust storm requires wind gusts up to 40 kmph and visibility below 1000m. Whereas, in Delhi’s case, even when the wind speed briefly repeated and visibility also dropped, it did not reach the set criteria for a desktop.

A similar dust storm was reported in mid-April, when flights were diverted and the city remained under red alert. An intense pre-monsoon storm was also observed on May 2, which fell several trees in the region and caused severe damage.

Episodic Winds

According to the Indian Institute of Tropical Meteorology, the air-quality index (AQI) at 8 AM was 236 or in the poor category, in Delhi. The AQI clocked at 292 on Thursday when the Commission of Air Quality Management in NCR and adjoining areas (CAQM) said that it “took stock of the current air quality scenario and noted that owing to events of dust from the Western region of the country, the concentration of PM 2.5 and PM 10 have increase significantly which has caused AQI to exhibit sharp increasing 10…The subcommittee attributes the sudden and sharp deviation in AQI to long-range transport of dust caused by substantial wind speed, which is purely episodic in nature.”