THE CONTEXT: Stubble burning became more prevalent in the 1980s with the introduction of mechanized harvesting, which left higher amounts of residue in fields. The practice has persisted despite growing awareness of its environmental impact due to deeply ingrained agricultural practices and economic constraints faced by farmers.
STUBBLE BURNING: It refers to the practice of intentionally setting fire to crop residues left in fields after harvesting, particularly rice and wheat. Farmers resort to this method primarily due to:
- Time constraints: The short window between harvesting one crop and sowing the next.
- Economic factors: The high cost of alternatives for stubble management.
- Lack of equipment: Insufficient access to machinery for in-situ management of crop residues.
CONTRIBUTION TO AIR POLLUTION: Stubble burning significantly contributes to air pollution in Delhi and the National Capital Region (NCR), especially during October and November. According to various studies:
- The Indian Institute of Tropical Meteorology (IITM) reported that stubble burning contributed up to 42% of Delhi’s PM2.5 levels on peak burning days in November. During stubble burning periods or wintertime, the contribution from main sources (farm fires in Punjab-Haryana or local sources within Delhi) could reach 65%-69%.
- A study by the Energy and Resources Institute (TERI) estimated that stubble burning accounts for 4-25% of Delhi’s winter air pollution, depending on the intensity of burning and meteorological conditions.
METEOROLOGICAL FACTORS
Transition from monsoon to winter: The period from October to December marks a critical transition in Delhi’s climate, characterized by:
- Declining temperatures
- Reduced wind speeds
- Increased atmospheric stability
These conditions create an environment conducive to the accumulation of pollutants. Meteorological factors significantly affect pollutant dispersion:
- Temperature inversions: Common in winter, these trap pollutants close to the ground.
- Wind patterns: Weak winds fail to disperse pollutants effectively.
- Humidity: High humidity can lead to the formation of secondary pollutants.
A study by the Indian Institute of Technology (IIT) Delhi found that unfavorable meteorological conditions can increase PM2.5 concentrations by up to 50% during winter months.
OTHER POLLUTION SOURCES
Vehicular emissions: The Centre for Science and Environment (CSE) reported that vehicles contribute about 40% of PM2.5 emissions in Delhi. A 2018 TERI study estimated that vehicles account for 28-39% of PM2.5 emissions in the city. Key issues include:
- Growing vehicle population: Delhi has over 11 million registered vehicles as of 2021.
- Diesel vehicles: Despite being only 3% of the fleet, they contribute significantly to PM emissions.
- Traffic congestion: Leads to increased idling and emissions.
Industrial activities: Industries, particularly in the NCR, contribute substantially to air pollution.
- The Central Pollution Control Board (CPCB) estimated that industries account for about 22% of PM10 emissions in Delhi-NCR.
- Small-scale industries and power plants in neighboring states significantly impact Delhi’s air quality.
Secondary Inorganic Aerosols (SIA): SIAs are formed through chemical reactions in the atmosphere and are a growing concern:
- A 2020 study by IIT Kanpur found that SIAs contribute up to 30% of PM2.5 in Delhi during winter.
- Major precursors include sulfur dioxide (SO2) and nitrogen oxides (NOx) from industrial and vehicular sources.
THE CHALLENGES:
- Variability in contribution: The impact of stubble burning on Delhi’s air quality varies significantly based on meteorological conditions. Studies have shown that its contribution can range from 1% to 58% of PM2.5 levels, making it difficult to establish a consistent baseline.
- Multiple pollutant sources: Delhi’s air pollution is a result of various sources, including vehicular emissions, industrial activities, and construction dust. Isolating the specific impact of stubble burning amidst these multiple sources poses a significant challenge.
- Seasonal variations: The contribution of stubble burning to Delhi’s air pollution is highly seasonal, peaking in October-November. This dynamic nature makes it challenging to implement year-round pollution control measures.
- Trans-boundary nature: A significant portion of Delhi’s air pollution originates from neighboring states. The Centre for Science and Environment reported that 55% of PM2.5 in Delhi comes from outside its territorial borders.
- Economic disparities: States like Punjab and Haryana, where stubble burning is prevalent, face different economic challenges compared to Delhi, influencing their ability and willingness to implement pollution control measures.
- Crop cycle constraints: Farmers in Punjab and Haryana typically have only 10-15 days between harvesting paddy and sowing wheat, making it challenging to manage crop residue effectively. Policies delaying paddy sowing to conserve groundwater further shorten the window for stubble management.
- Cost of alternatives: The cost of renting or purchasing machinery for in-situ stubble management is often prohibitive for small and marginal farmers. Despite government subsidies, many farmers find burning to be the most economical option.
- Lack of market for crop residue: The absence of a robust market for crop residue reduces the economic incentive for farmers to adopt alternative management practices.
THE CURRENT MEASURES:
- Reduction Efforts: According to recent data, Punjab has reduced the incidences of farm fires from over an order of magnitude from 17,467 in 2018 (as of October 25, that year) to 1,749 (October 25) 2024. Haryana has recorded 708 crop residue burning events as of October 27, 2023, showing a decrease from previous years.
- Technological Interventions: The central government has allocated Rs 2,440 crore for subsidies to provide over two lakh units of specialized farm machinery to farmers. More than 39,000 custom hiring centers have been established to allow small and marginal farmers to rent necessary equipment.
- Alternative Uses of Crop Residue: Haryana has initiated waste-to-energy projects, generating 84 MW of electricity from crop waste. Additional biomass plants have converted 3.5 lakh metric tonnes of straw into 30 MW of power.
- Air Quality Index (AQI) Monitoring: The Air Quality Index is categorized into six levels of Good (0-50), Satisfactory (51-100), Moderate (101-200), Poor (201-300), Very Poor (301-400), and Severe (401-500+). The Delhi Pollution Control Committee (DPCC) conducts daily monitoring of air quality at 40 locations across the city. Eight critical ambient air quality parameters are tracked to understand pollution trends and implement targeted interventions.
- Source Apportionment Studies: Source Apportionment Study of NCT of Delhi has identified major contributors to air pollution in the city. According to the Decision Support System (DSS) developed by the Indian Institute of Tropical Meteorology:
|
THE WAY FORWARD:
- Airshed Management: An airshed approach involves managing air quality over a common geographic area, irrespective of state boundaries. This approach recognizes that pollution sources and effects transcend administrative borders.
- Happy Seeder Technology: This tractor-mounted implement allows farmers to sow wheat without burning rice straw, reducing emissions and improving soil health. Studies show it can increase profits by 10-20% compared to burning.
- Bio Enzyme-PUSA: Developed by the Indian Agricultural Research Institute, this enzyme decomposes stubble into manure, enhancing soil quality and reducing the need for fertilizers.
- Biomass Utilization: Encouraging the use of crop residues in biomass-based power plants can reduce burning. Punjab plans to build 600 MW of biomass power capacity, though only 62.5 MW is operational so far.
THE CONCLUSION:
Delhi’s air pollution requires a multi-faceted approach involving regional cooperation, technological innovation, and robust policy measures. Sustained efforts and collaboration across all sectors are essential to achieve lasting improvements in air quality.
UPSC PAST YEAR QUESTIONS:
Q.1 Describe the key points of the revised Global Air-Quality Guidelines (AQGs) recently released by the World Health Organisation (WHO). How are these different from its last update in 2005? What changes in India’s National Clean Air Programme are required to achieve these revised standards? 2021
Q.2 What are the key features of the National Clean Air Programme (NCAP) initiated by the Government of India? 2020
MAINS PRACTICE QUESTION:
Q.1 Discuss the major contributors to air pollution in Delhi-NCR, focusing on stubble burning, vehicular emissions, and industrial activities. Evaluate the effectiveness of current measures.
SOURCE:
Spread the Word