Delhi’s Air Pollution Crisis: Causes, Trends, and Mitigation Measures
- October 28, 2024
- Posted by: OptimizeIAS Team
- Category: DPN Topics
Delhi’s Air Pollution Crisis: Causes, Trends, and Mitigation Measures
Sub: Env
Sec: Pollution
Why in News
Delhi’s air quality has deteriorated significantly as particulate matter (PM 2.5) levels rise to over 10 times the safe limit prescribed by the World Health Organization (WHO). The seasonal spike in pollution levels, aggravated by stubble burning in neighbouring states, Deepavali festivities, and meteorological conditions, has raised concerns about severe health impacts and the need for coordinated action across states.
Overview of Delhi’s Pollution Problem:
PM2.5 levels in Delhi recently soared to 160 micrograms per cubic meter, surpassing the WHO’s permissible limit of 15 micrograms.
Delhi’s 24-hour average Air Quality Index (AQI) reached 356 on October 23, placing it in the “very poor” category, with predictions of further deterioration if firecracker bans are not enforced during Deepavali.
Stubble burning in Punjab and Haryana coincides with this period, compounding Delhi’s air quality crisis.
According to Climate Trends, 54% of the wind from Punjab and 27% from Haryana carries particulate matter to Delhi. Each stubble-burning incident increases PM2.5 levels by 12.44 units on average.
Transportation within Delhi and vehicles entering the city contribute about 18% of PM2.5 levels. Vehicular emissions are especially high due to Delhi’s dense traffic and industrial activities.
Secondary Inorganic Aerosols (SIAs): SIAs, formed when sulphur dioxide (SO2), nitrogen oxides (NOx), and ammonia (NH3) react to create ammonium sulphate and nitrate, contribute up to 32% of Delhi’s winter pollution. Nearly 84% of SIAs originate outside Delhi, underscoring the need for cross-state solutions.
Meteorological Factors: Winter months bring a sharp reduction in wind speed, which prevents pollutants from dispersing and causes them to remain concentrated near ground level.
AQI Index score:
The AQI transforms complex air quality data of various pollutants into a single number for ease of understanding. The pollutants include PM 10, PM 2.5, Nitrogen Dioxide, Ozone, Carbon, etc.
Pollutants | Description |
PM 2.5 and PM 10 |
|
Nitrogen Oxides (NOx) |
|
Ozone |
|
Sulfur Dioxide (SO2) |
|
Ammonia (NH3) |
|
Lead (Pb) |
|
Carbon Monoxide (CO) |
|
WHO global air quality norms:
The World Health Organization (WHO) has raised the bar further to safeguard public health even before the global community could comply with the current benchmarks for clean air.
The WHO’s new air quality guidelines — Global Air Quality Guidelines (AQGs) — released September 22, 2021, has redefined the threshold of safe air.
This is the first revision after the last updating in 2005 — about 15 years ago. Currently, 90 per cent of the global population and nearly everyone in India is breathing air that defies the current guidelines of the WHO.
The primary focus is on significant tightening of the guidelines for particulate matter, which is responsible for the highest number of air pollution related deaths worldwide — nearly seven million. The guidelines for key gases have also been revised.
Need for Coordinated Action:
Airshed Approach: The “airshed approach” involves a cross-state, regional strategy to tackle air pollution by addressing sources beyond Delhi’s borders. Coordinated policy measures involving Punjab, Haryana, Uttar Pradesh, and Rajasthan, along with Delhi, are essential for meaningful air quality improvements.
Centralized Monitoring and Forecasting: The Indian Institute of Tropical Meteorology-Pune (IITM-Pune) maintains an air quality forecast system for cities across India, helping predict pollution trends and identify periods when stubble burning may significantly affect Delhi’s AQI.
Government-led Air Quality Early Warning Systems provide valuable data that can inform proactive measures, such as limiting vehicle emissions and restricting industrial activities during high-pollution days.
Long-term solutions include incentivizing alternative crop-clearing methods, increasing green cover, and promoting cleaner transport options.