Delhi Air Pollution: Causes, Effects, and Solutions

Delhi Air Pollution is one of the most pressing environmental issues in India, affecting millions of residents in the National Capital Region (NCR). Caused by a combination of vehicular emissions, industrial activities, construction dust, crop burning, and unique geographical factors, it worsens during the winter months, leading to dense smog and serious health problems. 

Understanding its causes, effects, and potential solutions is crucial for improving air quality and safeguarding public health.

Delhi Air Quality Index (AQI) Overview

The Air Quality Index (AQI) serves as a critical tool for effectively communicating the status of air quality and its potential health impacts to the public in easy-to-understand terms. It provides a snapshot of real-time air quality levels.

Parameters and Categories

The AQI in Delhi is calculated by measuring the concentrations of major pollutants, including: PM2.5, PM10, Nitrogen Dioxide (NO2​), Sulfur Dioxide (SO2​), and ground-level Ozone (O3​).

The AQI scale is divided into six categories, each corresponding to ambient pollutant concentration values and their likely health effects (health breakpoints).

Current Status of Delhi Air Quality

Delhi's air quality is routinely monitored by agencies like the System of Air Quality and Weather Forecasting and Research (SAFAR). On average, the city's AQI frequently ranges between 300-400 during the peak winter months, classifying the air as “Very Poor” to “Severe”.

When pollution levels exceed 401, they are marked as Severe, posing serious health risks to all individuals, particularly vulnerable groups like the elderly and children. During high-pollution days, PM2.5 levels are consistently well above the WHO's recommended safe limit, often exceeding 300 µg/m³. The government often issues advisories recommending that residents avoid outdoor activities during peak pollution hours.

Factors Behind the Persistent Delhi Air Pollution Crisis

The continuous deterioration of Delhi Air Pollution is not due to a single cause but is a result of a synergy between human-made activities, weather patterns, and unique geographical positioning.

Air Pollutants: Human-Made Sources

• Crop Burning (Stubble Burning): Farmers in the surrounding states (like Punjab and Haryana) burn agricultural residue to prepare fields for the next crop. The resulting smoke and pollutants are carried towards Delhi by north-westerly winds.

• Vehicular Emissions: The ever-increasing number of vehicles on Delhi-NCR roads leads to high emissions, which are a serious cause of smog and air pollution. Congested roads, often due to underdeveloped infrastructure, further aggravate this problem.

• Construction Dust: The rapid pace of construction and infrastructure development in the NCR generates large amounts of construction dust, adding significantly to the airborne particulate matter.

• Industrial Pollution: Many industries in the region have failed to adopt cleaner, environment-friendly fuels and techniques, emitting harmful gases that contribute to the pollution load.

• Firecrackers: The bursting of firecrackers, particularly during festivals in the winter, adds to the already existing severe pollution levels.

• Landfill Fires: The open burning of municipal solid waste, often at massive landfill sites, is a significant, constant contributor to pollution.

Weather and Geographical Conditions

• Stagnant Winds and Temperature Inversion: During winter, wind speeds often drop, causing stagnant winds that prevent pollutants from dispersing. Furthermore, a phenomenon called Low Air Inversion stops the upward movement of air, trapping the polluted layer close to the ground. * Geographical Location: Delhi is a landlocked city. North-westerly winds bring dust particles from regions like Pakistan and Afghanistan. Crucially, the Himalayas block the escape route for this polluted air, forcing the dust and pollutants to settle over the NCR region.

Impact of Delhi Air Pollution

The effects of poor Delhi Air Pollution are far-reaching, encompassing severe health issues, environmental damage, and even disruptions to daily life and commerce.

Health Risks

• Respiratory Illnesses: Continuous exposure to poor air quality can lead to the development of chronic conditions such as bronchitis, causing symptoms like coughing, breathlessness, and wheezing.

• Chronic Diseases: Poor air quality has the potential to cause serious chronic diseases, including heart disease, stroke, and lung cancer, ultimately reducing the lifespan of the population.

• Child Health: Epidemiological studies have demonstrated that exposure to poor air quality can negatively impact the natural growth and development of babies.

• Financial Burden: The resultant health effects impose a significant financial burden on both individual households and the government's healthcare system.

Environmental and Other Consequences

• Vegetation Damage: Poor air quality can damage crops and trees, negatively affecting vegetation growth, greenery, and potentially impacting food security.

• Water Pollution: Nitrogen oxides (NOx​) emitted from vehicular and industrial sources contribute nitrogen to aquatic ecosystems, which can cause eutrophication (excessive nutrient enrichment).

• Aviation Challenges: Air pollutants react with sunlight to produce haze, which severely affects visibility, thereby disrupting air traffic and flight operations.

Effective Measures to Tackle Delhi Air Pollution

The government has taken several coordinated steps to tackle the issue, primarily through the Commission for Air Quality Management (CAQM). CAQM was set up by the central government to coordinate and oversee efforts to improve air quality across Delhi, Punjab, Haryana, Rajasthan, and Uttar Pradesh.

Graded Response Action Plan (GRAP)

The Graded Response Action Plan (GRAP) is a set of emergency measures that are enforced when the air quality in Delhi-NCR deteriorates beyond a certain threshold. It was introduced in 2017.

GRAP has multiple stages (Stage I: Poor, Stage II: Very Poor, Stage III: Severe, Stage IV: Severe +) with corresponding restrictive measures. Steps under GRAP include:

• Strict enforcement of dust control measures at Construction and Demolition (C&D) sites.

• Daily sweeping and watering of roads.

• Coordination of traffic movements to facilitate smooth flow and reduce emissions.

• Increasing parking fees to discourage private vehicle usage.

• Bans on construction and demolition activities, school holidays, and restrictions on vehicular movement in higher stages.

Vehicular, Industrial, and Agricultural Control Measures

• Odd-Even Vehicle Scheme: Vehicles with odd and even registration numbers ply on alternate days to reduce vehicular density and emissions.

• Peripheral Road Construction: The Eastern and Western Peripheral Highways were constructed to allow large commercial vehicles to bypass Delhi entirely, reducing the city's pollution burden.

• Ban on Old Vehicles: Diesel vehicles over 10 years old and petrol vehicles over 15 years old have been banned to reduce emissions from older, less efficient engines.

• Promotion of Electric Vehicles (EVs): Governments are actively promoting the adoption of EVs as a cleaner alternative to fossil fuel vehicles.

• Control of Stubble Burning: Farmers are subsidized to use farm machinery that eliminates the need to burn stubble. Fines are also imposed, and new decomposition techniques are promoted.

• Compliance with BS-VI Norms: Vehicles plying in Delhi-NCR must adhere to Bharat Stage VI (BS-VI) norms, which significantly reduce polluting emissions.