Air Quality Index: Gaps in India's Pollution Assessment

Why in the News?

India's Air Quality Index (AQI), calculated by the Central Pollution Control Board (CPCB), faces criticism for excluding carcinogens and capping pollutant readings, understating health risks.

Key Highlights

• India has 83 of the world's 100 most polluted cities, with stalled progress despite rising health costs.

• The AQI uses eight pollutants: PM2.5, PM10, nitrogen dioxide, sulphur dioxide, carbon monoxide, ozone, ammonia, and lead.

• Biomass burning is a major Indian source of carbon monoxide and fine particles, linked to respiratory and heart diseases.

• The AQI caps readings at 500, understating extreme pollution like Mundka's Diwali peak of 3,744.

• Delhi's monitoring stations showed 125 missing hours with PM2.5 levels exceeding 1,000 on the DPCC website.

• Air pollution caused 1.67 million deaths in India in 2019, with COPD, stroke, and heart disease as major contributors.

Know the Basics

• Air Quality Index (AQI): A numerical scale used to communicate air pollution levels based on eight pollutants.

• PM2.5 and PM10: Particulate matter with diameters up to 2.5 and 10 microns, respectively, harmful to respiratory health.

• Temperature inversion: A weather condition where warm air traps pollutants close to the ground, worsening air quality.

• Biomass burning: Combustion of organic materials like crop residue, a significant pollution source in India.

Detailed Analysis

AQI Calculation and Exclusions

• The AQI is determined by the pollutant with the worst sub-index, potentially understating combined risks from multiple pollutants.

• Carcinogens like benzene, arsenic, and nickel are excluded, despite their known health impacts.

• Hourly PM2.5 readings above 380 are capped at 500, misrepresenting extreme pollution events.

Health Impacts of Air Pollution

• PM2.5 exposure is linked to hypertension, diabetes, and dementia, with soot particles detected in fetal tissues.

• Respiratory emergencies rise on high-pollution days, as shown by an ICMR study across five cities.

• Young children and older adults face disproportionate risks, with pollution causing four times the disease burden of tobacco-linked infections.

Data Gaps and Monitoring Issues

• Delhi's monitoring stations often lack PM2.5 data, distorting assessments of peak pollution hours.

• Stations recording fewer than 16 hours of data are excluded from AQI calculations, further reducing accuracy.

• Public apathy and weak enforcement compound the problem, with seasonal interventions failing to address systemic issues.

Policy Recommendations

• Higher vehicle taxes, parking charges, and affordable public transport are needed to reduce automobile emissions.

• Cleaner fuels, faster electric-vehicle adoption, and stricter enforcement against industrial pollution are proposed solutions.

• Pradhan Mantri Ujjwala Yojana's shift away from biomass fuel must be accelerated to reduce household pollution.

Significance for India

• India's AQI methodology and health impacts are highly relevant for Prelims and Mains questions on pollution and governance.

• Understanding AQI exclusions helps evaluate the effectiveness of current policies and interventions.

• UPSC could test aspirants on the health costs of pollution and the need for systemic reforms in governance.

• India's shared airshed with neighbouring countries highlights the importance of international cooperation in pollution control.

Challenges

• The AQI excludes critical carcinogens, misrepresenting health risks.

• Data gaps in monitoring stations distort pollution assessments, especially during peak hours.

• Public apathy and weak enforcement hinder effective policy implementation.

• Seasonal interventions like smog towers and sprinklers are cosmetic and fail to address systemic issues.

Way Forward

• CPCB must revise AQI calculations to include carcinogens and remove caps on pollutant readings.

• State governments must ensure rigorous monitoring and data transparency at all stations.

• Parliament should legislate stricter vehicle-emission standards and incentivise electric-vehicle adoption.

• Regional cooperation with Pakistan, Nepal, and Bangladesh is essential for managing shared pollution sources.