Low visibility cancels 8 trains as cold wave grips north India

NEW DELHI: Mercury levels dropped significantly across north India, after a cold wave gripped multiple parts of the region on Sunday, with the railway services taking a hit.

19 trains were delayed, two rescheduled and eight cancelled due to low visibility in the national Capital, while the air quality remained "moderate" throughout the day.

The Central Pollution Control Board stated that high moisture content in the air could increase smog in the coming week.

With minimum temperature recorded at 7.8 degrees Celsius, Delhi woke up to a clear Sunday morning. Humidity was recorded at 73 per cent at 8.30 am, an official of the Indian Meteorological Department said.

Visibility was recorded at 1,500 meters at 5.30 am, and improved significantly to 3,000 meters at 8:30 am.

The CPCB also observed that Delhi was faced with a complex set of meteorological factors in early November, when pollution levels had peaked.

The situation, between November 7-12, was more hostile as compared to last year's peak pollution episode, recorded between October 30-November 7, CPCB's air lab chief Dipankar Saha said.

According to data shared by the CPCB, the concentration of PM2.5, particulates measuring less than 2.5 microns, ranged between 357 and 611 micrograms per cubic metre (ug/m3) during this year's week-long emergency pollution spell.

Last year, the levels oscillated between 197 and 709 ug/m3. Products of vehicular and industrial combustion among others, PM2.5 are air-borne particles which can lodge deep in the lungs and trigger respiratory and cardiovascular diseases. Winds blew at a rate of 1 to 1.4 metres per second, while during last year's emergency spell, it had gone up to 3 metres per second.

Relative humidity this year oscillated between 60.2-75.8 per cent this time, as compared to last year's 47.8-63.3.

High humidity signifies the presence of moisture in the air, which helps trap pollutants near the surface, spiking levels of pollution. Lastly, average levels of temperature hovered between 21.6-23.6 degrees Celsius, lower than 22.9-26.1 recorded in 2016.

During winters, there is a drop in inversion layer, which is a boundary beyond which pollutants cannot disperse into the upper layer of the atmosphere.