Air Pollution and AQI Framework for UPSC

Air Pollution and AQI in India: Pollutants, Sources, Health, Meteorology, and Policy Response

Air pollution is a public health and economic challenge, closely linked to climate through short-lived pollutants. This article explains key pollutants (PM2.5/PM10 and gases), health impacts, why winter smog peaks, how the National Air Quality Index (AQI) works, and the policy stack—Air Act, NCAP, CAQM/GRAP, BS-VI, industrial norms, stubble measures. It keeps jargon low and focuses on what matters for understanding and action.

What We Breathe: Pollutants in Focus

AQI: The Common Scale

The National Air Quality Index reports eight pollutants (PM2.5, PM10, SO₂, NO₂, CO, O₃, NH₃, Pb). The worst sub-index sets the AQI category: Good (0–50, green), Satisfactory, Moderate, Poor, Very Poor, Severe (401–500, maroon). The aim is simple risk messaging—important for public advisories and for triggering actions like GRAP in Delhi-NCR.

PM2.5 vs PM10: Why the Fine Particles Matter Most

PM10 is largely dust and settles faster. PM2.5 remains airborne longer and often forms secondarily from SO₂/NOx/NH₃. Because of its size it reaches the alveoli and bloodstream, driving the largest health burden. Controlling combustion sources and precursor gases is central to PM2.5 reduction.

Health and Economic Burden

• Respiratory and cardiovascular disease, lung cancer, strokes, adverse pregnancy outcomes, and impaired lung development in children.
• Ground-level ozone damages crops (notably wheat), lowering farm income.
• Economic costs include productivity losses and higher healthcare expenditure; studies show benefits of clean air outweigh abatement costs.

Why Winter Smog Peaks in North India

• Temperature inversion: Cold air trapped under a warm layer prevents vertical mixing—like a lid.
• Low wind speeds: Stagnant air over the Indo-Gangetic Plain traps emissions.
• Humidity and fog: Moisture helps particles grow; smog becomes visible.
• Seasonal emissions: Post-harvest stubble burning, higher biomass use, and fireworks add to traffic/industry baseline.

Source Profiles

• Transport: Diesel vehicles, old fleets, congestion; two-wheelers dominate numbers.
• Industry and power: Coal TPPs, brick kilns, steel/cement, diesel generators.
• Residential: Biomass cooking and heating, kerosene lamps.
• Agriculture: Stubble burning (NW India), NH₃ from fertilizers/livestock.
• Construction and road dust: Material handling, unpaved shoulders.
• Waste: Open burning and landfill fires.
• Natural: Dust storms (pre-monsoon), sea salt on coasts, forest fires.

Monitoring the Air

• CPCB/SPCB networks with continuous (CAAQMS) and manual stations; many cities still lack dense coverage.
• Satellite data (AOD) and models show regional patterns but need ground validation.
• CEMS for industries stack emissions; calibration and enforcement determine usefulness.
• Low-cost sensors map hotspots but require QA/QC to avoid misleading data.

Legal and Institutional Framework

• Air (Prevention and Control of Pollution) Act, 1981: Empowers CPCB/SPCBs for standards and consent.
• Environment Protection Act, 1986: Umbrella for emission norms and notifications.
• NGT and courts: Orders on stubble burning, construction dust, waste burning; enforce compliance.
• CAQM: Commission for Air Quality Management coordinates NCR states, issues binding directions.

NCAP: National Clean Air Programme

Launched 2019 for 131+ non-attainment cities; aims at ~40% PM reduction by 2026 (targets tightened from earlier 20–30% by 2024). Cities craft action plans spanning transport, industry, dust, waste, and awareness. Funding is partly performance-linked; capacity gaps and airshed-level coordination remain challenges.

GRAP for Delhi-NCR

The Graded Response Action Plan links AQI bands to actions: dust control and PUC enforcement (early stages), bans on diesel gensets and construction, restrictions on older vehicles and polluting industries at Severe, truck entry bans and school closures at Severe+. CAQM issues orders; critics note emergency focus must be paired with year-round structural measures (fleet renewal, power plant compliance, waste management).

Transport Measures

• BS-VI fuels/engines (10 ppm sulphur) with DPF/SCR in diesels; fuel economy standards and scrappage policy for old vehicles.
• Public transport expansion (buses/metro), last-mile connectivity, and parking/traffic management reduce congestion.
• Electrification: FAME incentives, PLI for batteries, e-bus procurement; effectiveness depends on clean power and grid readiness.

Industry and Power

• Thermal power plant norms (2015) for SO₂/NOx/PM/Hg—FGD rollout is delayed; stricter enforcement and financing support are needed.
• Brick kilns moving to zig-zag technology cut coal use and PM; compliance varies.
• Fuel bans (petcoke/furnace oil) in NCR except allowed uses; gasification or cleaner fuels in clusters.
• DG sets regulated/banned during severe episodes; push for cleaner back-up (gas/RE + storage).

Construction, Dust, and Urban Form

• Site enclosures, water spraying, wheel washing, covering materials, and on-site storage are mandated; mechanical road sweeping and paved shoulders reduce resuspension.
• Urban planning: compact growth, green/blue spaces, and transit-oriented development reduce vehicle km and dust.

Agriculture and Stubble Management

• Short harvest windows drive paddy residue burning in Punjab/Haryana/UP.
• Alternatives: Happy/Super Seeder and balers, bio-CNG/biomass power markets, Pusa bio-decomposer, crop diversification to shorter-duration rice or millets.
• Penalties exist, but incentives, service centres, and assured biomass offtake are crucial for change.

Waste and Landfills

Open waste burning and landfill fires emit PM, dioxins, and VOCs. Solid Waste Rules mandate segregation and ban burning; biomethanation/composting for wet waste and scientific landfills with bioremediation of legacy dumps are key to cutting emissions.

Indoor Air Pollution

Biomass cooking smoke remains a major exposure for women and children. Ujjwala expanded LPG access; sustained use depends on refill affordability and supply. Ventilation, chimneys, and avoiding incense/coil overuse indoors also matter. Clean cooking gives both health and climate co-benefits (black carbon reduction).

Airshed Approach and Source Apportionment

Pollution crosses city/state borders. NCR, central industrial belts, and IGP need regional plans, not city silos. Source apportionment studies (seasonal) guide tailored actions—secondary particles can form a large share of winter PM2.5, so controlling SO₂/NOx/NH₃ matters alongside dust and tailpipes.

Climate Linkages

• Black carbon, methane, and ozone are short-lived climate pollutants; cutting them brings quick climate and health gains.
• Coal-to-clean power reduces CO₂ and co-pollutants; EVs and clean cooking shift emissions to the power sector, so grid decarbonisation is important.

Enforcement and Transparency

• Environmental compensation (fines) and closure orders are tools; deterrence depends on consistent follow-through.
• Public dashboards for station data and industrial compliance build accountability.
• Remote sensing and audits can flag non-compliance (kilns, construction), but response speed is critical.

Protecting Vulnerable Groups

• Health advisories for Severe days: N95 masks, avoid outdoor exercise, stagger school timings.
• Outdoor workers need protective gear and shifted hours; hospitals and elder care facilities should maintain indoor filtration and backup clean power.
• Communication in simple terms (color codes, dos/don’ts) improves adherence.

Economics of Clean Air

Cost–benefit analyses repeatedly show health savings exceed abatement costs (FGDs, clean cooking, public transport). Financing can blend government funds, green bonds for buses/metro, viability gap for FGDs, and CSR for dust/waste management. Clean air also protects tourism and investment attractiveness.

Data to Update Before Using

• Latest count of non-attainment cities and NCAP target year.
• FGD installation status (MW compliant vs pending) in TPPs.
• E-bus deployment and EV sales shares; metro expansion numbers.
• Stubble fire counts trend after decomposer and machinery schemes.

Takeaway: Air pollution control is about tackling combustion, dust, and waste together, guided by good data and enforced standards. AQI offers a common language; NCAP, CAQM/GRAP, BS-VI, industrial norms, stubble and waste measures form the toolkit. Success rests on consistent enforcement, regional coordination, clean energy, and making sure communities have viable alternatives to polluting practices.

Seasonal Patterns Beyond Winter

• Pre-monsoon: Dust storms raise PM10 across northwest/IGP; ozone can spike with high sunlight.
• Monsoon: Wet deposition improves PM briefly, but construction resuspension can continue; coastal cities see sea-salt influence.
• Post-monsoon: Stubble fires plus cooler, calmer conditions set up winter episodes; fireworks add short spikes.

Case Examples

• Beijing’s turnaround: Coal-to-gas switch, industrial relocation, vehicle quotas, and strict enforcement cut PM in a decade—shows regional coordination matters.
• Ahmedabad: Heat and air advisories integrated; CEMS sharing with industries improved compliance.
• Surat: Industrial clusters switched to gas, showing role of fuel infrastructure.
• Delhi-NCR: Demonstrates that emergency steps alone cannot compensate for slow structural fixes (power plant compliance, transit, waste, stubble support).

Indoor–Outdoor Link

Outdoor PM infiltrates indoors; efficient buildings need proper ventilation/filtration to avoid indoor buildup of PM, CO₂, VOCs. Schools/hospitals near busy roads should use filters during high-AQI days. Air purifiers help locally but do not replace source control.

Policy Gaps and Priorities

• Airshed institutions beyond NCR are weak; regional bodies can align states on inventories, actions, and monitoring.
• Data transparency: real-time publication of industrial emissions and enforcement outcomes builds trust.
• Capacity: many ULBs lack staff/equipment for dust control and enforcement; funding and training are critical.
• Rural air quality: biomass cooking and small kilns are under-monitored; clean cooking scale-up and rural waste management matter.

Technology Choices: What Works

• Works: DPF/SCR for diesels, FGDs and low-NOx burners for TPPs, zig-zag kilns, wet suppression for dust, remote sensing for compliance checks.
• Limited: Smog towers and ad-hoc water spraying without dust management plans have minor, local impact.
• Emerging: AI-based traffic management to cut idling, calibrated low-cost sensor grids for local action.

Behavioral and Communication Tools

Clear messaging on AQI health impacts, public transport incentives, car-pooling, and discouraging waste burning are low-cost levers. “LiFE” lifestyle nudges can pair with policy (parking fees, congestion charges) to shift behaviour.

Link to Climate and Energy Transition

Grid decarbonisation multiplies the benefit of EVs and clean cooking. Methane capture from waste and agriculture and black carbon reduction offer quick climate and health wins. Aligning air quality and climate policies prevents lock-in of high-carbon assets and avoids double work.

Metrics for Accountability

• Annual average PM2.5/PM10 trends, not just episode counts.
• Compliance rates: FGDs installed, zig-zag conversion %, PUC checks per day, construction dust violations penalised.
• Modal share shifts: public transport, cycling/walking, EV uptake.
• Stubble fire counts vs previous years; area under decomposer/mulching/biomass offtake.

Financing the Transition

Green bonds for buses/metro and waste infrastructure, viability gap funding for FGDs and clean fuel shifts, and PES-like arrangements for watershed/green cover can spread costs. International climate finance can support air-quality co-benefit projects if integrity and MRV are strong.

Building Design and Cooling

Energy-efficient buildings with natural ventilation, cool roofs, and shading reduce AC demand and associated emissions. Schools and hospitals should adopt indoor air quality standards, especially in high-AQI cities.

Public Health Integration

Health systems can track pollution-linked admissions, issue advisories, and coordinate with pollution control boards. Pharmacovigilance for asthma/COPD medicine spikes can serve as indirect indicators. Occupational health standards for workers in high-exposure jobs (traffic police, construction) need enforcement.

What Not to Confuse

• CO₂ is a climate gas, not part of AQI; methane affects climate and ozone but is not in AQI either.
• Ozone in AQI is ground-level, not the stratospheric ozone hole.
• “Severe+” is a GRAP trigger label; AQI scale still tops at 500.

Regional Specificities

• Indo-Gangetic Plain: High background due to geography and emissions; strong focus on combustion sources and secondary aerosol precursors.
• Coastal cities: More ventilation; tackle industry, port emissions, and construction dust rather than blaming stubble.
• Arid/semi-arid: Dust management, paving shoulders, shelterbelts; pre-monsoon storms key driver.

Looking Forward

• Strengthen airshed governance and data systems; integrate air quality into city master plans and transport policy.
• Accelerate clean power and industrial compliance; align carbon market design with local pollutant reductions.
• Scale clean cooking and clean agriculture practices; support farmers with viable no-burn options.
• Keep public health at the centre—advisories, protection for workers, and targeted support for vulnerable groups.

Ozone: The Often Ignored Pollutant

Ground-level ozone is a secondary pollutant formed by NOx and VOCs in sunlight. It irritates lungs and reduces crop yields. Cutting ozone needs control of vehicle/industry NOx, solvent and fuel vapour VOCs, and better traffic management. Strategies focused only on PM can miss ozone in sunny, pre-monsoon months.

Odd–Even and Smog Towers: Quick Takes

• Odd–Even traffic schemes: Can reduce peak congestion and emissions if enforced and paired with strong public transport; impact varies and is temporary.
• Smog towers: Very limited area of influence, high cost; best seen as symbolic—source control delivers real gains.

Implementation Challenges

• Fragmented accountability between multiple agencies (transport, power, ULBs, agriculture, industry).
• Data gaps and calibration issues reduce confidence; need regular audits of CAAQMS/CEMS.
• Financing for small industries and farmers to adopt cleaner tech is often missing; credit and targeted subsidies can help.
• Enforcement fatigue: periodic drives without sustained follow-up erode credibility.

Citizen and Community Roles

• Reporting waste burning and construction violations via helplines/apps; response should be time-bound.
• Adopting public/active transport, car-pooling, and maintaining vehicles (PUC) reduces tailpipe load.
• Segregating waste and composting shrinks open burning; supporting clean cooking in households and community kitchens builds uptake.

Enforcement Examples

• Closure of non-compliant brick kilns and stone crushers in NCR during Severe episodes; permanent compliance demands fuel/tech shifts, not just closures.
• Environmental compensation charges on trucks entering NCR; effective when combined with freight rationalisation and rail/water transport options.
• NGT and court orders on halting construction without dust control, and on waste burning penalties, show legal levers when agencies lag.

Linking Air Quality with Mobility Planning

Transport plans should integrate bus lanes, cycling networks, and pedestrian safety to make mode shifts attractive. Parking pricing and congestion charging can nudge behaviour if reliable alternatives exist. Freight consolidation and last-mile electrification reduce diesel use. Compact city design cuts trip lengths and exposure.

Health System Preparedness

• Integrate AQI alerts into hospital readiness; stock inhalers and protective gear during forecasted severe days.
• Occupational safeguards for traffic police, street vendors, sanitation workers—rotations, masks, periodic health checks.
• Public campaigns on when to seek medical help for pollution-related symptoms.

Regional Coordination Examples and Needs

• NCR’s CAQM is an airshed body; similar coordination is needed for central industrial belts and other multi-state airsheds.
• Data-sharing on emissions inventories and enforcement actions across states prevents leakages (industry moving to looser jurisdictions).
• Joint procurement of monitoring/mitigation services can lower costs for smaller cities.

Role of Agriculture Policy

MSP and procurement patterns influence crop choice and harvest timing. Incentivising millets and shorter-duration rice, improving straw markets (bioenergy, packaging), and integrating soil health card advice to cut fertilizer overuse can lower both burning and NH₃ emissions. Extension services and custom hiring centres are central to adoption.

Equity Lens

Pollution hits poorer households harder—they live near busy roads/industrial areas, rely on biomass, and have less access to healthcare. Fair policy means affordable clean fuel, better public transport, targeted support for small firms and farmers, and inclusive consultation when imposing restrictions.

Resilience to Wildfire and Dust

Forest fires and grassland burns contribute to episodic PM spikes; early warning, community fire lines, and regulated grazing can reduce risk. Shelterbelts and soil moisture conservation help manage dust in arid regions.

Data Literacy for the Public

Understanding AQI, pollutant-specific issues (ozone vs PM), and proper mask use (N95, not cloth) empowers people to take protective steps. Schools and workplaces can incorporate basic air literacy alongside heat/cold advisories.