'So-called PM 3.0' needs to worry about PM2.5: Congress’ dig over Delhi air quality
Jairam Ramesh of Congress said the National Clean Air Programme focuses heavily on PM10, but it is the finer particulate matter PM2.5 that is the real killer as far as public health is concerned
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Context
Delhi's air quality has deteriorated to the 'very poor' category for the first time this season, triggering the implementation of Stage 2 of the . The opposition Indian National Congress criticized the central government's environmental policies, highlighting the failure of the to adequately address PM2.5, a highly dangerous microscopic pollutant, which remains significantly above safety limits.
UPSC Perspectives
Environmental
The core issue revolves around the distinction between PM10 and PM2.5 (Particulate Matter), which are microscopic solid or liquid matter suspended in the atmosphere. PM2.5 particles are smaller than 2.5 micrometers in diameter (about 3% the diameter of a human hair) and are significantly more hazardous to public health than the larger PM10 because they can penetrate deep into the respiratory tract and enter the bloodstream. The , launched in 2019, aims for a 20-30% reduction in particulate matter concentration by 2024, but the opposition argues it focuses too heavily on PM10. Furthermore, India's National Ambient Air Quality Standards for PM2.5 are significantly less stringent than the guidelines; India's 24-hour average limit is 60 micrograms per cubic meter, whereas the WHO recommends 15 micrograms per cubic meter. For UPSC, understanding the health impacts of PM2.5, the differences between national and international air quality standards, and the goals of the NCAP are crucial.
Governance
The management of air pollution in the National Capital Region involves specific regulatory frameworks and bodies. The Air Quality Index (AQI), launched by the , transforms complex air quality data of various pollutants into a single number, nomenclature, and color for easy public understanding. When the AQI in Delhi breaches specific thresholds, the is invoked. GRAP is a set of emergency measures categorized into four stages (Poor, Very Poor, Severe, and Severe Plus) that are implemented incrementally to prevent further deterioration of air quality. The decision to invoke these stages rests with the , a statutory body established to coordinate and oversee efforts to improve air quality in the NCR and adjoining areas. UPSC aspirants must be familiar with the structure and function of the CPCB, the CAQM, and the specific triggers and measures associated with the different stages of GRAP.
Geographical
The recurring severe air pollution in Delhi and North India during the winter months is a complex interplay of geographical and meteorological factors. Delhi's landlocked geography prevents the easy dispersal of pollutants, unlike coastal cities where sea breezes help clear the air. During winter, temperature inversion occurs, where a layer of cold air near the ground is trapped by a layer of warmer air above it, acting like a lid that traps pollutants close to the surface. This is exacerbated by lower wind speeds during this season. Additionally, the region experiences significant trans-boundary pollution, primarily from agricultural stubble burning in neighboring states like Punjab and Haryana, which is carried towards Delhi by prevailing north-westerly winds. Understanding these geographical and meteorological phenomena is essential for answering Mains questions on the causes and seasonal variations of air pollution in North India.