Smog,haze to persist in city: Experts

On Tuesday,the maximum particulate matter (PM)10 and PM2.5 levels recorded were 360 µg/m3 and 200 µg/m3,respectively. (The permissible levels for PM10 — huge dust particles — is 100 µg/m3 and PM2.5 — a harmful pollutant that leads to respiratory disorders among humans — is 60 µg/ m3).

Data available under SAFAR air quality forecasting system show that the minimum temperature in Delhi has been around 8-10 degrees Celsius for around two weeks,while the maximum has remained around 24-26 degrees.

While the minimum temperature will remain at the same level,maximum temperature will gradually drop,which may worsen particulate pollution in poor the to very poor category,Dr Sunil Peshin,head,environmental monitoring research centre,Delhi,said.

However,a dip in the day and night temperatures will keep the boundary layer at a much lower level and will not allow it to go up even during day,Dr Gufran Beig said.

Fog delays 200 flights,30 trains

Dense fog and near-zero visibility conditions over Delhi and NCR caused major disruption to air,rail and road traffic on Tuesday. Over 200 flights were delayed,many by over five hours,while over 30 trains,including Rajdhani and Duronto,were running late by more than seven to eight hours.

At the Indira Gandhi International Airport,flight operations were completely closed on both runways from 4 am to 10 am on Tuesday. Airport officials said schedules of all flights went haywire after 5 am,when visibility dropped below 50 metres.

“The fog started to become dense around 5 am and the visibility went below 50 metres,the minimum required for landing under poor visibility conditions using the CAT-III B instrument landing system (ILS),” the official said.

Low visibility procedures (LVP) had to be initiated at 9.25 pm on Monday on Runway 29-11,and lasted for more than 14 hours till 11.44 am on Tuesday. At runway 28-10,LVP was put in place for over seven hours,from 4.30 am to 11.40 am,on Tuesday.

“During the period of LVP,a total of 154 flights operated. Of these,10 departures and nine arrivals had to be cancelled and seven arriving flights had to be diverted to Jaipur and Mumbai,” an official said.

The minimum visibility for an aircraft to take off under low visibility conditions is between 125 and 150 metres,depending on the size of the plane.

Meanwhile,departures of several trains including Howrah Rajdhani,Bhubaneswar Rajdhani,Sealdah Rajdhani,Howrah Duronto,Patna Sampoorna Kranti Express,Mahabodhi Express and Jabalpur Superfast Express were rescheduled.

According to the Met department,atmospheric conditions have witnessed a swift change since Saturday,with cyclonic formations having come to a complete halt over southeast India,reviving a fast approaching winter pattern in the northern plains.

Fresh and increased levels of humidity and absence of any significant wind flow over the last 48-hours has been the reason behind a thick blanket of fog covering most areas in Delhi and the national capital region.

The Met department said the arrival of an active western disturbance is likely,“which could cause light rainfall at a few places across the plains of northwest India on December 24 and 25”.