Mumbaiites witnessed an unusual phenomenon on Wednesday as a plume of dust enveloped several parts of the city. Weather officials attributed the haze to a dust storm in Rajasthan that has been persistent in the region for the past few days.
"The landmass in Rajasthan heated up unusually causing sand and dust particles to flow with the wind, which is moving in a north-westerly pattern. This phenomenon was definitely unusual and rarely occurs in coastal cities," said VK Rajeev, director, Indian Meteorological Department (IMD), western region. The respirable suspended particulate matter (RSPM) also shot up to alarming levels.
"The dust storm increased the RSPM levels to an average of 1,200 microgram/cubic metre at the Bandra monitoring station and reached a high of 1,400 microgram/cubic metre. Construction and road-repair activities in the city might have worsened the concentration of particulate matter," said Ajay Deshpande, joint director, pollution assessment monitoring and surveillance.
The permissible RSPM limit is 100 microgram/cubic metre.
The dust storm, however, did not cause a dip in temperatures. "The temperatures remained normal throughout the day. But, there are chances that the maximum might drop in the evening because of clouding," Rajeev added.
The storm reduced visibility to 500m-1km compared to the normal visibility of 4 to 5km. The poor visibility inconvenienced motorists. Nikhil Khedekar, 27, who rides his motorcycle to office daily said, "I started from Mankhurd just before noon and from RK Studio up till Andheri (west), I had to ride slowly because of the dusty weather," said Khedekar, an advertising professional.
The dusty weather also affected people suffering from respiratory ailments.
"I had gone shopping to Bandra when I started feeling dizzy and breathless. Being a bronchitis patient I immediately took a cab back home," said Rhea Khurana, Kandivli resident.
Parts of Thane, Navi Mumbai, Tarapur and Dahanu that are closer to Gujarat border were worst affected.
Dust storms usually disperse faster when the wind speed is high. But on Wednesday, the city witnessed a normal wind speed of around 20-22 km per hour, causing the dust clouds to persist for a longer time
Weathermen at the New Delhi bureau said the sandstorms in the Arabian Peninsula might be the source of the dust storms in northern and western India.
"The winds in Rajasthan were blowing at 40km per hour, raising dust in the atmosphere. Light wind suspends the dust in the air while a strong wind speed carries it ahead," said BP Yadav, director, IMD, New Delhi.