• The Air Quality Index (AQI) of Delhi has improved within the ‘poor’ category.
• As per a forecast from the Central government’s System of Air Quality and Weather Forecasting And Research (SAFAR) the AQI is expected to stay in the higher end of ‘poor’ to the lower end of ‘very poor’ category for the following days.
• During the lockdowns, Delhi saw among the cleanest air since comprehensive records have been kept since 2015.

Air Pollution in Delhi

• Air pollution in Delhi-NCR and the Indo Gangetic Plains is a complex phenomenon that is dependent on a variety of factors.

Change in Wind Direction:

• October usually marks the withdrawal of monsoons in Northwest India and during this time, the predominant direction of winds is northwesterly.
• The direction of the wind is northwesterly in summers as well, which brings the dust from northern Pakistan and Afghanistan.

Reduced Wind Speed:

• High-speed winds are very effective at dispersing pollutants, but winters bring a dip in wind speed overall as compared to in summers which makes the region prone to pollution.
• Also, Delhi lies in a landlocked region which does not have a geographical advantage that eastern, western or southern parts of the country enjoy where the sea breeze disperses the concentrated pollutants.

Stubble Burning:

• Stubble burning in Punjab, Rajasthan and Haryana is blamed for causing a thick blanket of smog in Delhi during winters.
• It emits large amounts of toxic pollutants in the atmosphere which contain harmful gases like methane (CH4), carbon monoxide (CO), volatile organic compounds (VOC) and carcinogenic polycyclic aromatic hydrocarbons.
• Farm fires have been an easy way to get rid of paddy stubble quickly and at low cost for several years.

Vehicular Pollution:

• It is one of the biggest causes of dipping air quality in Delhi in winters and around 20% of PM2.5 in winters comes from it.

Dust Storms:

• Dust storms from Gulf countries enhance the already worse condition. Dry cold weather means dust is prevalent in the entire region, which does not see many rainy days between October and June.
• Dust pollution contributes to around 56% of PM10 and the PM2.5 load.

Dip in Temperatures:

• As temperature dips, the inversion height is lowered and the concentration of pollutants in the air increases when this happens.
• Inversion height is the layer beyond which pollutants cannot disperse into the upper layer of the atmosphere.

Firecrackers:

• Despite the ban on cracker sales, firecrackers are a common sight on Diwali. It may not be the top reason for air pollution, but it definitely contributed to its build-up.

Construction Activities and Open Waste Burning:

• Large-scale construction in Delhi-NCR is another culprit that is increasing dust and pollution in the air. Delhi also has landfill sites for the dumping of waste and burning of waste in these sites also contributes to air pollution.

Problems Caused by Air Pollution

• Air pollution severely affects human health. It is found to cause low birth weight in children, tuberculosis, asthma, ischemic heart disease, nasopharyngeal and laryngeal cancers, cataracts, etc.
• According to some research, air pollution can also impair cognitive development.
• Air pollution is associated with infections & diseases that kill around 600,000 children under five years of age every year.
• Several studies reveal a higher prevalence of symptoms of chronic bronchitis in areas with higher particulate air pollution.
• Nearly 2.5 million people die worldwide each year from the effects of outdoor or indoor air pollution. (National Geographic)
• Air pollution also affects the environment adversely. Many pollutants are greenhouse gases and this leads to global warming. Burning fossil fuels releases carbon dioxide which has the biggest impact on global warming.

Steps Taken to Control Delhi’s Air Pollution

Various steps have been taken by the government (central and state governments) to tackle the menace of air pollution in Delhi-NCR. Some of the measures are given below.

• In October 2020, the Supreme Court-appointed a one-man committee, Justice Lokur Committee, to monitor and curb the occurrences of stubble burning in Punjab, Haryana and Uttar Pradesh. Read more about this committee in CNA dated Oct 17, 2020.
• The Ministry of Environment, Climate Change and Forests notified the Graded Response Action Plan (GRAP) in 2017.
  • These are institutionalised measures to be taken only when the air quality in Delhi NCR deteriorates beyond a certain threshold.
  • It is only to be implemented in emergency situations.
  • The steps would be taken to prevent PM10 and PM2.5 levels to go beyond the ‘moderate’ national Air Quality Index (AQI) category.
  • GRAP enumerates a series of measures to be taken based on the quality of air.
  • In the case of severe+ category, one of the measures also includes shutting down of schools.
  • Read more on the Graded Response Action Plan in the linked article.

• Construction & demolition (C&D) waste management rules have been notified which mandate the segregation of C&D waste into various categories for safe disposal and further processing.
• Red Light On, Gaadi Off campaign was an initiative by the Delhi Government that ran in Oct-Nov 2020 under which commuters driving vehicles were urged to switch off their vehicle engines while waiting for the green light at traffic lights.
• The Odd-even rule was introduced by the Delhi Government according to which vehicles with odd and even registration numbers would ply on the road on alternate days. This was particularly aimed at reducing smog in the region.
• The state government of Delhi also introduced a policy to preserve and plant trees in a bid to increase the green cover and have carbon sinks.
• Anti-smog guns and smog towers are installed and used in the city.
• Prevention of stubble burning is a key component of reducing air pollution in the Delhi NCR area. 
  • The subsidy is provided to the farmers for procuring the Turbo Happy Seeder, which is a machine fitted on tractors that can cut and uproot stubble and eliminates the need to burn stubble.
  • The ICAR has also come up with the PUSA Decomposer, which is a capsule that can be used to make a spray which when sprayed on crop residue hastens its decomposition.

• Mass Rapid Transport System (MRTS) is being built as a means to provide citizens with non-polluting alternative sources of transportation.
• The adoption of the Bharat Stage VI norms and the big push being given to electric vehicles steps in the right direction in curbing vehicular pollution.

Way Forward

• Appropriate political will and aware citizenry is a prerequisite to tackle the menace, otherwise, all the measures will remain on paper only and greater public transparency is essential to the success of winning the war on air pollution.
• There is no better watchdog than active citizens, which is why the pollution targets must be made public every year for their perusal and to be evaluated at the end of the year.
• Breathing clean air is a fundamental right of every Indian citizen. Therefore, human health must become a priority when it comes to tackling air pollution.