As we enter the prewinter season in North India, the national capital continues to witness a deterioration in its air quality. Delhi’s air quality crisis has reached alarming levels, with the city's Air Quality Index (AQI) recorded at 360 recently, indicating a “very poor” air quality. Delhi is turning into a gas chamber with constant deterioration in air quality increasing health challenges for its 20 million residents. A huge number of residents witness health issues like asthma, COPD, etc. AIIMS Delhi has seen a sudden rise in OPD patients with respiratory health issues like asthma, COPD, etc, due to increased levels of air pollution in Delhi.

Why Does Air Quality Decline During Winter?

The winter months bring a perfect storm of conditions that trap pollutants close to the ground, creating a thick blanket of smog over the city. Several factors contribute to this seasonal phenomenon:

1. Weather Patterns and Temperature Inversion : In winters when the air is cold, the landlocked geography of Delhi leads to the trapping of pollutants near the ground, preventing them from dispersing. This phenomenon, called temperature inversion, occurs when a layer of warm air sits above cooler air at ground level, trapping the cooler air and pollutants below. As a result, the pollution accumulates closer to the ground, worsening air quality.

2. Low Wind Speed : Delhi typically experiences low wind speeds during winter, which further contributes to pollution build-up. During this season, there’s often not enough wind to disperse the particulate matter and gases in the atmosphere, allowing pollutants to linger for longer periods.

3. Increased Burning of Biomass and Stubble Burning : Farmers in the neighboring states of Punjab, Haryana, and Uttar Pradesh burn crop residue, or stubble, after the harvest season, primarily in October and November. This practice releases massive amounts of smoke, which drifts over Delhi and worsens its air quality. Despite various efforts to provide alternatives, stubble burning remains a significant contributor to Delhi’s winter air pollution.

4. Vehicular Emissions and Industrial Activities : Delhi is a hub of economic activity, with countless vehicles on the roads and industries operating throughout the city and surrounding areas. During winter, increased fuel combustion from vehicles (as people keep engines running longer in colder temperatures) and emissions from industries, such as coal-burning plants, release pollutants that remain close to ground level, reducing air quality.

5. Unmanaged Solid Waste : According to National Environmental Engineering Research Institute (NEERI), around 8000 m tonnes of solid garbage are produced everyday in Delhi; however, only roughly 5000 to 5500 m tonnes of waste are removed by the authorities each day. This contributes to the accumulation of trash. This data is excluding hazardous and non-hazardous waste from industries. The amount of trash increases during the festive & wedding season, adding to the issue. 

6. Ongoing Construction Works : Extensive construction activities in Delhi contribute significantly to dust and air pollution, accounting for nearly 56% of the particulate matter (PM10 and PM2.5) levels. The ongoing infrastructure development releases fine dust particles into the air, heavily impacting air quality and posing serious health risks to residents. This is the very reason that the state government puts bans on construction activities during winters.

7. Increased Population : Delhi's burgeoning population is a significant contributor to its severe air pollution problem. As the city's population grows, so does the demand for transportation, housing, and energy. This increased demand leads to a surge in vehicular emissions, industrial activities, and construction projects, all of which release harmful pollutants into the air. Additionally, a larger population often translates to increased waste generation, which, if not managed properly, can contribute to air pollution.

8. Use of Fireworks During Festivals : Diwali, celebrated in October or November, often involves widespread use of fireworks. This festive tradition contributes heavily to the spike in air pollution, with the smoke and particulate matter from firecrackers creating a hazardous smog that can take days to dissipate.

Measuring Air Quality: Understanding the AQI

The Air Quality Index (AQI) is a tool used to measure and categorize air quality levels. AQI values range from 0 to 500 and classify air quality into categories, from “Good” to “Hazardous”:

0-50: Good

51-100: Moderate

101-200: Unhealthy for Sensitive Groups

201-300: Unhealthy

301-400: Very Unhealthy

401-500: Hazardous

During winter, Delhi’s AQI often crosses 400, putting it in the "Hazardous" category. In some severe cases, AQI levels have even exceeded 500, leading authorities to declare health emergencies.

The Health Impacts of Poor Air Quality

Prolonged exposure to high pollution levels poses serious health risks, affecting not only vulnerable groups like children, the elderly, and those with preexisting conditions but also healthy individuals.

1. Respiratory Issues : Particulate matter (PM2.5 and PM10), which are tiny particles in polluted air, can penetrate deep into the lungs, leading to respiratory issues like asthma, bronchitis, and chronic obstructive pulmonary disease (COPD). Children and elderly people are particularly susceptible to these respiratory ailments.

2. Cardiovascular Problems : Studies have shown that exposure to air pollution can increase the risk of heart attacks and strokes. The pollutants in the air can trigger inflammation in blood vessels, affecting heart health over time.

3. Weakening of the Immune System : Poor air quality can weaken the immune system, making people more susceptible to infections and diseases. The tiny pollutants can enter the bloodstream and potentially cause long-term health issues by triggering inflammation throughout the body.

4. Mental Health and Cognitive Function : Emerging studies indicate that exposure to high pollution levels could impact mental health, leading to conditions like anxiety and depression. There’s also research suggesting that pollution might affect cognitive development in children and increase the risk of neurodegenerative diseases like Alzheimer’s in older adults.

Steps Taken to Improve Air Quality

Over the years, the Indian government and local authorities have implemented various measures to combat Delhi’s air pollution. Some of these initiatives have shown promise, though challenges remain.

• Graded Response Action Plan (GRAP) : The Graded Response Action Plan is a set of emergency measures implemented based on air quality levels. For example, if the AQI reaches severe levels, restrictions on construction activities, the closure of schools, and a halt to coal-based power generation may be enforced.

• Promotion of Electric Vehicles (EVs) : Delhi’s government has introduced policies and incentives to promote the use of electric vehicles, aiming to reduce the number of diesel- and petrol-based vehicles on the road. Transitioning to EVs is expected to lower emissions and improve air quality in the long term.

• Ban on Certain Industrial Activities : During high pollution periods, certain industrial activities that are heavy polluters, such as brick kilns and coal-fired plants, are temporarily suspended. The government has also pushed for the adoption of cleaner fuels and technologies in industries to reduce emissions.

• Encouraging Farmers to Adopt Alternatives to Stubble Burning : Efforts are being made to provide alternatives to stubble burning, including subsidizing equipment that can manage crop residue. However, more incentives and awareness are needed to encourage large-scale adoption among farmers.

• Air Purifiers and Public Awareness : While air purifiers alone cannot solve the pollution crisis, their use is encouraged in schools, hospitals, and homes. Awareness campaigns are also conducted to educate the public on minimizing outdoor activities during severe pollution periods and using masks to reduce exposure.

What Can Residents Do?

While government actions are crucial, residents can also adopt certain practices to protect themselves and contribute to the fight against air pollution in Delhi.

• Reduce Car Usage : Carpooling, using public transport, or choosing to walk or cycle for short distances can reduce emissions. Residents should also consider switching to EVs, if feasible, to lower their carbon footprint.

• Limit Outdoor Activities : On days when the AQI is extremely high, limiting outdoor activities can help reduce exposure to harmful pollutants. Exercising indoors and using air purifiers can also help minimize the health risks associated with pollution.

• Opt for Masks : Wearing N95 or similar masks can filter out particulate matter and protect against respiratory ailments. Although masks are not a permanent solution, they provide immediate protection during high-pollution periods.

• Indoor Air Quality Improvement : Houseplants like aloe vera, spider plants, and snake plants can help improve indoor air quality to some extent. Additionally, keeping windows closed on heavily polluted days and using air purifiers indoors can help reduce indoor pollution levels.

Long-Term Solutions and Hope for Change

Achieving clean air in Delhi will require sustained efforts on multiple fronts. While government policies and technological solutions are crucial, tackling this issue will also require public cooperation and community engagement. Cities around the world have successfully reduced pollution with a combination of policies and active citizen participation. For Delhi, addressing the root causes of pollution, promoting sustainable practices, and ensuring strict enforcement of regulations are key to making the city a safer place to live, especially during winter.

Conclusion

Winter air pollution in Delhi is a complex issue influenced by various factors, from weather patterns to human activities. While efforts to combat pollution have shown some progress, Delhi’s citizens continue to endure hazardous air quality every winter. To truly transform Delhi’s air, a holistic approach is needed—one that involves government action, community involvement, and a commitment to sustainable practices. With coordinated efforts, Delhi can hopefully look forward to winters with clearer skies and healthier air in the years to come.