Mumbai air quality drops to poor as dust from Pakistan, Iran shrouds city

A day after a western disturbance and cyclonic circulation in Rajasthan triggered unseasonal rains in Mumbai, a thick layer of haze and dust engulfed the financial capital on Sunday, pushing the city’s air quality index to the “poor” category.

A day after a western disturbance and cyclonic circulation in Rajasthan triggered unseasonal rains in Mumbai, a thick layer of haze and dust engulfed the financial capital on Sunday, pushing the city’s air quality index (AQI) from to the “poor” category.

A hazy and dusty atmosphere over the skyline of South Mumbai on Sunday. (Anshuman Poyrekar/HT photo)

As per the Central Pollution Control Board’s daily AQI bulletin, Mumbai recorded an AQI of 247 on Sunday, up from a “satisfactory” AQI of 99 a day earlier.

As per the System of Air Quality and Weather Forecasting And Research (SAFAR), the AQI on Sunday evening stood at an index value of 333, the highest in at least six months.

While several citizens believed that a dust storm had hit the city, the India Meteorological Department (IMD) and weather experts said the haze was caused by “dust raising winds” triggered by the same western disturbance which resulted in rainfall on Saturday. It also reduced Sunday’s temperature to its lowest January maximum temperature on record – 23.8 degrees Celsius (January’s highest maximum temperature, as per historical records, was at 37.4 degrees Celsius in 2006).

“Hazy skies over parts of North Konkan (including Mumbai) and North Madhya Maharashtra today was due to suspended dust particles which were carried into the region along with the westerly winds,” KS Hosalikar, scientist, surface instrument division, IMD, said.

“A prominent dust event is affecting parts of Maharashtra (including Mumbai-MMR), Madhya Pradesh and Gujarat. This dust event has been triggered by a recent western disturbance, which is also causing the ongoing dip in Mumbai’s temperature,” independent meteorologist Akshay Deoras, who analysed the circumstances surrounding the haze, said.

Deoras explained that even though the western disturbances were present at high altitudes, they can induce a low pressure nearer to the Earth’s surface.

“This western disturbance induced a low pressure zone near Rajasthan and adjoining parts of Pakistan on the night of January 21. This caused an increase in the surface wind speed over Pakistan and adjoining eastern Iran, which started blowing the dust over these regions from the early morning hours of January 22. Within a few hours, the dust was visible over the Gulf of Oman and northern Arabian Sea, following which it entered Gujarat on the same day,” he said.

“Winds from the northwest direction near the ground pushed the dust into Mumbai-MMR on January 23. Apart from Mumbai-MMR, this dust has already spread across several districts of Maharashtra such as Nashik, Ahmadnagar, Pune, Dhule, Nandurbar, Jalgaon, Buldhana, Akola and Aurangabad districts of Maharashtra on Sunday afternoon,” he added.

Mumbai has seen multiple such dust events in the past, including a prominent one in March 2012.

The source of dust has always been the arid regions of the Middle East and Pakistan, experts said. However, such events over the Middle East are generally more frequent during spring and summer season when factors such as high temperature, atmospheric instability, strong northwesterly winds and thunderstorms create ideal conditions for the triggering of dust storms. Dust storms observed in June and July are not able to impact Mumbai due to the monsoon conditions, they explained.

Officials clarified that the haze witnessed on Sunday comprised more inert, crustal materials than pollutants. “This haze comprises mainly sand, because it originates from the Middle East where the conditions are sandier. It cannot be defined as smog, which comprises a more complex mixture of pollutants,” Gufran Beig, project director, SAFAR, said.

Sachin Ghude, a scientist at the Indian Institute of Tropical Meteorology in Pune, warned that the air quality and visibility will remain poor till at least the afternoon of January 24.