Anthropogenic & Natural Causes of Air Pollution in Delhi | Special Note on Farmers Issue of Straw Burning

Air pollution has been a constant news theme over the last two weeks. The other few being – Debate on banning of 500, 1000 rupee notes & Ease of business to some extent.

We will start this write up by quickly introducing the basics of AQI (Air Quality Index) and what it measures:

Here are two graphical timelines of places in Delhi and Bangalore. Note that the constant theme is prominence of PM2.5



AQI, developed by IIT Kanpur & sponsored by Central Pollution Control Board. Keep these 5 points in mind before we go into Particulate matter pollution in detail:

– The USP of AQI is  “One Number- One Colour-One Description.”

– Previous index only monitored 3 parameters. New AQI will monitor 8 type of pollutants. 8 pollutants * 6 categories.

– But the AQI doesn’t monitor Benzene – a carcinogen chemical from Petrol and diesel. Also, there are no conditional safety protocols.

– Industrial units use non-standardised machines to measure PM2.5 & other levels & come under the self-certification regime. So GoI has no way of checking on these products.

What is Particulate Matter? What is PM2.5?

PM is a term used to describe the mixture of solid particles and liquid droplets in the air. It can be either human-made or naturally occurring. Examples: Dust, ash and sea-spray

PM (including soot) is emitted during the combustion of solid and liquid fuels, such as for power generation, domestic heating and in vehicle engines. It varies in size (i.e. the diameter or width of the particle)

PM2.5 means the mass per cubic metre of air of particles with a size (diameter) generally less than 2.5 micrometres (µm)

Why is PM2.5 bad?

Being tiny, these particles easily reach the lungs. From there, they can travel through the bloodstream and reach the heart. Long exposure to PM2.5 can worsen asthma and heart conditions (it is also carcinogenic). They also cause runny nose, sneezing and coughing.

Unfortunately, planting more trees does nothing to solve the problem. Since PM2.5 are particles and not gases, they can’t be processed by the leaves.

What are the anthropogenic and natural causes of air pollution in Delhi?

#1. Natural Causes: 

a) Low temperature in winter leads to low wind velocity, which reduces the dust dispersal process

b) Landlocked cities , no moderate sea effect

#2. Anthropogenic factors:

a) Road dust – Dust emanating from unpaved roads and peak construction activities causes silicosis.

b) Vehicular emissions – Increased number of diesel vehicles, huge commuters, absence of integrated transport public infrastructure adds the problem

c) Industrial vehicles – Dirty power plants, coal usage in hotels, diesel generators contributes SO2 and NOX which can cause major respiratory ailments

d) Waste burning Crop residue burning in neighbouring states – Punjab, Haryana, Uttar Pradesh transfers pollutants to Delhi

e) Improper waste management – Burning of waste at landfills and lack of waste segregation at source adds particulate matter into the atmosphere

How big is this menace of crop residue burning/ straw burning?

An analysis of Delhi’s air pollution and future trends by the National Environmental Engineering Research Institute (NEERI), a CSIR body found out that 60% of Delhi’s particulate matter pollution comes from neighbouring Haryana and Uttar Pradesh (straw burning + vehicular fumes)

Moreover, even if Delhi were to adopt the cleanest-grade fuel available, ensure that power plants in the vicinity adopt stringent emissions and ensure tidy pavements, pollution would persist well above globally-recommended safe levels, unless neighbouring states too adopted similarly stringent policies.

Why do farmers burn their crop residues?

Rice residue has to be burned, removed or incorporated into the soil in order to prepare elds for the next wheat crop. Farmers also burn rice residue also because many believe that it has a beneficial effect on yields.

– Burning increases the availability of some nutrients such as phosphorus and potassium in the short run

– However, it can also result in the loss of plant nutrients such as nitrogen, potash, sulphur and negatively a ect the local microbial population and organic carbon

But, a growing major concern regarding residue burning emerges from its e ects on air pollution and climate change. Incomplete combustion of biomass such as agriculture residues generates black carbon which is the second largest contributor to global warming after carbon dioxide.

What has the government done to alleviate this problem?

#1. In a December 2015 order, the National Green Tribunal had called for a curb on straw burning, and had recommended that satellite-based monitoring mechanisms be adopted and local government officers engaged to take action against stubble burning.

#2. It had also suggested engaging the concerned patwaris, block development officers and police stations for immediate action via SMS.

#3. The NGT had also recommended putting agricultural residue to alternative uses like energy generation, and for producing ethanol, paper and packaging material, to benefit the farmers and also to protect the environment.

The problem with that is: So far, seven power plants that generate electricity from straw have been built in Punjab, and six more are on the drawing board. But together, all 13 would consume only 1.5 million of the 20 million tons of straw produced in Punjab every year, or less than 10 % of total straw.

#4. On behalf of the Centre, the Department of Agriculture and Cooperation in the agriculture ministry made a policy decision to extend financial assistance to the farmers for procuring ‘Happy Seeder’, which is used for sowing wheat without burning any rice residue.

While Punjab needs about 1,000 such machines, at present it has only about half as many. A plan worth Rs 6,600 crore was drawn up to purchase machines like choppers and shredders, ‘Happy Seeders’ and ‘zero tillage’ but the Centre delayed releasing the payment.

Read this curated op-ed to understand the efficient use of rice straw


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