Delhi Air Quality Crisis – Causes and Consequences

Delhi experienced deterioration in air quality in December 2024. The city initially enjoyed its cleanest air in five years. However, this improvement was short-lived as the Air Quality Index (AQI) surged to alarming levels. This shift prompted the reintroduction of anti-pollution measures in the capital. About the reasons behind this rapid decline is essential for addressing air quality issues.

Recent Air Quality Trends

In early December, Delhi reported its best air quality in recent years. However, by mid-December, the AQI reached 379, categorising it as ‘very poor’. The Central Pollution Control Board indicated that without intervention, the situation could worsen to ‘severe’ levels. The city’s air quality fluctuates , influenced by various factors.

Low Wind Speed

One of the primary factors contributing to poor air quality is low wind speed. Calm winds trap pollutants close to the ground. Wind speeds below 10 km/h are particularly detrimental. On one recent day, wind speeds dropped to 6 km/h, preventing the dispersion of pollutants. The India Meteorological Department forecasted similar conditions, exacerbating pollution levels.

Cold Wave Conditions

Cold wave conditions also played role. The India Meteorological Department defines these conditions as temperatures dropping below 4.1 degrees Celsius. Delhi experienced its earliest cold wave since 1996, with temperatures dipping to 4.9 degrees Celsius. These cold temperatures lower the inversion height, trapping pollutants in the lower atmosphere.

Transport Sector Contributions

The transport sector is a major contributor to Delhi’s air pollution, accounting for approximately 16.94% of total emissions. Other contributors include industrial emissions, which represent 8.36% of pollution. The ongoing Graded Response Action Plan aims to mitigate these contributions, yet the impact remains .

Lack of Rainfall

Another critical factor in the worsening air quality is the lack of rainfall. While a light drizzle occurred on December 9, it was insufficient to clear the accumulated pollutants. The forecast for the following week showed no signs of substantial precipitation, leaving the air quality vulnerable to further deterioration.

Government Response Measures

In response to the declining air quality, the government reinstated several measures. These include transitioning to hybrid classes for younger students and banning specific vehicle types. Such actions aim to reduce emissions and improve the city’s air quality.

Public Health Implications

The poor air quality poses serious health risks for residents. Increased levels of particulate matter can lead to respiratory issues and other health complications. Continuous monitoring and proactive measures are vital for safeguarding public health in Delhi.

Future Outlook

The ongoing challenges of air quality in Delhi highlight the need for long-term solutions. Enhanced public transportation, stricter emission controls, and increased green spaces could help mitigate pollution levels. Awareness and community involvement are also crucial for encouraging a cleaner environment.

Questions for UPSC –

1. Examine the impact of low wind speed on air quality in urban areas.
2. Critically discuss the role of the transport sector in contributing to air pollution in metropolitan cities like Delhi.
3. Analyse the relationship between cold wave conditions and air pollution levels in North India.
4. Point out the significance of rainfall in determining air quality, particularly in urban environments.

Answer Hints:

1. Examine the impact of low wind speed on air quality in urban areas.

1. Low wind speeds trap pollutants near the ground, increasing concentration in the air.
2. Wind speeds below 10 km/h are particularly detrimental to air quality.
3. Calm winds prevent the dispersion of pollutants, leading to higher AQI levels.
4. Forecasts indicate sustained low wind conditions can exacerbate pollution further.
5. Effective air quality management requires understanding and mitigating the effects of wind patterns.

2. Critically discuss the role of the transport sector in contributing to air pollution in metropolitan cities like Delhi.

1. The transport sector accounts for approximately 16.94% of total air pollution in Delhi.
2. Vehicle emissions, particularly from older models, contribute to particulate matter.
3. Urban traffic congestion exacerbates emissions, particularly during peak hours.
4. Government measures like vehicle bans aim to reduce transport-related pollution.
5. Transitioning to cleaner public transport options is crucial for long-term air quality improvement.

3. Analyse the relationship between cold wave conditions and air pollution levels in North India.

1. Cold wave conditions lower temperatures, which can trap pollutants in the atmosphere.
2. Inversion layers become lower during cold weather, preventing pollutants from dispersing.
3. Delhi experienced its earliest cold wave in decades, worsening air quality .
4. Cold temperatures can persist, prolonging poor air quality conditions.
5. About this relationship is essential for forecasting and managing air pollution during winter months.

4. Point out the significance of rainfall in determining air quality, particularly in urban environments.

1. Rainfall helps to wash away airborne pollutants, improving air quality .
2. Light or insufficient rainfall does not effectively clear accumulated pollutants.
3. Forecasts indicating a lack of rainfall can predict worsening air quality conditions.
4. Urban areas often depend on rainfall for natural air purification processes.
5. Long-term strategies should include enhancing urban green spaces to promote rainfall and improve air quality.