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Current Affairs

Air pollution rise in October

Date: 18 October 2020 Tags: Miscellaneous

Issue

Every year in October, Delhi’s air quality starts to dip with the arrival of winter season and rise in agricultural fires in northern belt.

 

Background

Air pollution in Delhi and the whole of the Indo Gangetic Plains is a complex phenomenon that is dependent on a variety of factors. The first and foremost is the input of pollutants, followed by weather and local conditions.

 

Details

  • October usually marks the withdrawal of monsoons in Northwest India. During monsoons, the prevalent direction of wind is easterly.

  • These winds, which travel from over the Bay of Bengal, carry moisture and bring rains to this part of the country.

  • Once monsoon withdraws the predominant direction of winds changes to north westerly. During summers, too, the direction of wind is north westerly and storms carrying dust from Rajasthan and sometimes Pakistan and Afghanistan.

  • Along with the change in wind direction, the dip in temperatures is also behind the increased pollution levels. As temperature dips, the inversion height is lowered. The concentration of pollutants in the air increases when this happens.

  • High-speed winds are very effective at dispersing pollutants, but winters bring a dip in wind speed over all as compared to in summers.

  • The combination of these meteorological factors makes the region prone to pollution. When factors such as farm fires and dust storms are added to the already high base pollution levels in the city, air quality dips further.

 

Role of farm fires

  • Farm fires have been an easy way to get rid of paddy stubble quickly and at low cost for several years.

  • With the use of combine harvesters, the practice became more common as the harvester leaves behind tall stalks, which have to be removed before replanting.

  • But the practice gained widespread acceptance starting 2009, when the governments of Punjab and Haryana passed laws delaying the sowing of paddy.

  • The aim of passing this law was to conserve groundwater as the new sowing cycle would coincide with monsoons and less water would be extracted.

  • This, however, left very little time for farmers to harvest paddy, clear fields, and sow wheat for the next cycle.

  • The paddy straw and stalks have high silica content and are not used to feed livestock. The easiest, but the least productive, way to get rid of it is to set it on fire.

  • The practice has thrived despite efforts made by the Centre and state governments primarily because the alternatives, like the happy seeder machine which helps mulch the residue, are seen as unavailable, and money and time consuming by smaller farmers.