New Delhi: It's not entirely stubble burning. What else is fueling air pollution?

India's capital New Delhi has been enveloped by thick smog as air pollution worsened, which led to an increase in the concentrations of fine particles in the air above acceptable limits. But is air pollution in Delhi fuelled by the absence of Western disturbances? The latest report provides answers.

For many years, New Delhi has been ranked as one of the most polluted cities in the world as winter approaches the region. With the end of the Monsoon and the arrival of the Autumn season, winds in the northwest region slow down and temperatures begin to fall. The conditions become favourable for capturing contaminants from the environment.

Not just that, construction dust, pollution, factories, and stubble burning are some of the sources of the smog.

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However, a recent report by Climate Trends,an environment NGO, suggests that stubble-burning incidences in the neighbouring agrarian states of Haryana and Punjab have decreased by 38.04 per centand 47.8 per cent, respectively. As a result, the weight of high air pollution levels falls on local emissions and weather conditions.

As quoted by the report, Mahesh Palawat, the Vice President of Meteorology and Climate Change, at Skymet Weather, said: "Weather conditions are presently very conducive for the spike in air pollution. Temperatures have also started coming down, leading to the formation of mist and haze during the morning hours."

Palawat added, "The mist contains water vapours where the pollutants get deposited and remain suspended near the Earth's surface. Further, the absence of any weather activity, as well as light winds, are not letting pollutants move away from Delhi-NCR."

Experts have said that the air in the planetary boundary layer (the lowest section of the atmosphere) is thinner during the winter because the cooler air near the Earth's surface is dense.

The cooler air is confined beneath the heated air above, forming a kind of atmospheric 'lid'. This is called the winter inversion. The contaminants discharged do not have enough space to disperse in the atmosphere as the vertical mixing of air occurs solely inside this layer.

Meteorologists have issued a warning that there will be more bad air quality days as minimum temperatures fall further in the season.

Palawa added, "The more the minimum temperatures dip, the thicker will be the inversion layer. And the thicker the inversion layer, it would be more difficult for sun rays or winds to penetrate through this layer and disperse the pollution level."

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In the last few years, the world has witnessed persistent changes in the weather patterns caused by climate change. To understand how it is important to know about the Western Disturbance (WD) and the process of bringing winter rains over Northwest India.

WD is an extratropical cyclone that forms in the Mediterranean region and provides heavy winter rain to the northwestern sections of the Indian subcontinent. It also extends as far east as northern Bangladesh and south-eastern Nepal.

But there have been discrepancies in the Western Disturbances, especially this year as the experts have not seen any after Oct 12.

Less WDs lead to lesser weather activity, which means the wind speed continues to be light and not good enough to push away the pollutants.

"For dispersion of pollution, cities need to cut down on emissions across sectors and at source. However, weather conditions in the form of rains would bring some immediate relief but with increasing climate change, these systems have also become inconsistent," the Climate Trendsreport noted.

(With inputs from agencies)