Meteorological experts have indicated that air pollution usually increases in winter because of the dense cool air and lack of wind which traps pollutants close to the ground, often creating smog.

Although this past week, pollutant levels have been higher than usual because of cloudy weather and increased humidity in the air, it was not smog (which is fog mixed with pollutants) but dust particles that has caused lack of visibility.

In the beginning of the week, air pollutant levels touched 242 micrograms per cubic metre of air (ug/m3) — the highest recorded level this month till date. November has seen an an average air pollution level of 150ug/m3.

Warm balmy afternoons and cold evenings have taken a toll on Mumbaikars’ health. Hospitals are witnessing a 15 to 20 per cent rise in patients suffering from respiratory disorders. “The city air harbours a potent mix of post-Diwali pollution coupled with seasonal change and fluctuating weather. Patients treated for chronic pulmonary obstructive disorder (COPD), which causes respiratory distress, has seen an increase by 15 to 20 per cent,” said Dr Tejal Shah, chest physician at the Godrej Memorial Hospital in Vikhroli. “Patients come with symptoms like shortness of breath and incessant wheezing.”

“Clouds are coming in because of cyclonic activity on the Andhra coast. Humidity has increased along with the temperature which causes suspended particulate matter (pollutants) to keep circulating in the atmosphere, locked in by clouds. Moisture keeps these pollutants from dispersing or drying up, trapping them in the air,” said Dr Gufran Beig of the Indian Institute of Tropical Meteorology (IITM), Pune.

“The only remedy for this condition is for the sun to come out. This will help disperse some of the pollutants,” he said. Experts have said there is a chance of more cyclonic activity on the Andhra coast in the coming week and cloudiness might continue till the cyclones stop.

Mumbai and parts of Maharashtra and Goa have been seeing dense clouds and spurts of rainfall since the past week, which resulted in an increase in humidity and temperature. The regional Meteorology department in Mumbai attributed this change to a trough travelling upwards from Lakshadweep and said the weather should revert to its normal winter course within a few days.

Average pollutant levels in micrograms per cubic metre of air (ug/m3)

October: Nitrous Oxide (NOx)- 94.5 / Respirable Suspended Particulate Matter (RSPM) - 106.5

November: NOx- 142 / RSPM- 148.5

Highest level of pollutants in November

November 24th: Nox - 228 ug/m3

November 25th: RSPM - 242 ug/m3

Safe limit: 100 ug/m3