Delhi's air quality to deteriorate to 'poor' category

New Delhi, June 6

The air quality in Delhi is likely to deteriorate and crossover from "moderate to poor" category on Tuesday due to strong surface winds raising dust locally and also transporting it from nearby region, the India Meteorological  Department (IMD) warned on Sunday.

The predominant pollutant will be PM10 as the strong surface winds are favourable for raising dust locally and transport of dust from nearby region, said the National Weather Forecasting Centre of the IMD.

It further warned that the air quality is likely to remain in the "moderate to poor category" for the subsequent five days.

Meanwhile, it said also that the air quality over the national capital is likely to remain in "moderate category" on Sunday as well as Monday.

The IMD has also predicted partly cloudy sky with a possibility of very light rain and drizzle on Sunday as the predominant surface wind is likely to be coming from Southwest directions of Delhi with wind speed 10-16 kmph.

"The predominant surface wind is likely to be coming from northwest or West directions of Delhi with wind speed 16-28 kmph and partly cloudy sky with possibility of very light rain and drizzle on Monday. The wind speed is likely to coming from West directions of Delhi on Tuesday too with wind speed up to 28 kmph, mainly clear sky and strong surface winds (speed 25-35 kmph) during the day."

Predicted maximum mixing depth is likely to be approximately 3,500 metre on Sunday and 4,100 metre on Monday and 4,000 metre on Tuesday over Delhi, the IMD said.

However, it said that the maximum ventilation index is likely to be approximately 23,000 meter2/second on Sunday and 33,000 m2/s on Monday and 46,000 m2/s on Tuesday.

"The ventilation index lower than 6,000 m2/s with average wind speed less than 10 kmph is unfavourable for dispersion of pollutants."

The strong surface winds are favourable for raising dust locally and transport of dust from nearby region, thereby making PM10 the predominant pollutant. —IANS