Reason for Delhi October pollution Level

Source: The Indian Express

Syllabus: GS-3- Environment

Context:   Delhi’s air quality started to dip as the AQI touched very poor for the very first time this October.

Why does air pollution rise in October each year?

  • 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.
  • Once monsoon season ends, the main direction of winds changes to north westerly from easterly winds.
  • According to a study conducted by scientists at the National Physical Laboratory, 72 per cent of Delhi’s wind in winters comes from the northwest, while the remaining 28 per cent comes from the Indo-Gangetic plains.
  • The dip in temperature is also behind the increased pollution levels. The inversion height which is the layer beyond which pollutants cannot disperse into the upper layer of the atmosphere is lowered and concentration of pollutants in the air increases.
  • Wind speed dips in winters which are responsible for dispersing pollutants. AQI dips even more when factors such as farm fires and dust storms are added to the already high base pollution levels in the city.

What is the role of farm fires?

  • Stubble burning which is a way to get rid of paddy stubble quickly and at a low cost, gained widespread acceptance when 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 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 alternatives like the happy seeder machine which helps covering the residue, are seen as unavailable, and money and time consuming by smaller farmers.
  • A 2015 source-apportionment study on Delhi’s air pollution conducted by IIT-Kanpur also states that 17-26% of all particulate matter in Delhi in winters is because of biomass burning.
  • The System of Air Quality and Weather Forecasting and Research (SAFAR) has developed a system to calculate the contribution of stubble burning to Delhi’s pollution.
  • Last year, during peak stubble burning incidents, its contribution rose to 40%.

What are the other big sources of pollution in Delhi?

  • Dust and vehicular pollution are the two biggest causes of dipping air quality in Delhi in winters.
  • Dust pollution contributes to 56% of PM 10 and the PM2.5 load at 59 t/d, the top contributors being road 38 % of PM 2.5 concentration, the IIT Kanpur study said.
  • According to the IIT Kanpur study, 20 % of PM 2.5 in winters comes from vehicular pollution.

What are the steps taken by the government to address the pollution?

  • The effort to reduce vehicular pollution, which experts say is more harmful as it is released at breathing level, the following has been done:
  • The introduction of BS VI (cleaner) fuel
  • Push for electric vehicles
  • Odd-Even as an emergency measure
  • Construction of the Eastern and Western Peripheral Expressways

Way forward

  • With vehicles back on the road, temperature dipping and stubble burning starting, Delhi’s air is set to get worse and so the steps introduced by the government should be implemented properly to find some relief from the pollution in Delhi.
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