Introduction

Delhi’s Air Quality Index (AQI) touching 500 raises concerns about the persistent air pollution crisis in India, particularly in the National Capital Region (NCR). The AQI has become a household term as restrictions like the odd-even scheme are enforced in Delhi, and even Mumbai’s air quality is being scrutinized by the Bombay High Court.

Key Pollutants and Their Sources

• The major pollutants of public health concern include particulate matter (PM10 and PM2.5), nitrogen dioxide, ozone, and sulfur dioxide.
• PM arises mainly from fuel combustion, nitrogen dioxide from road traffic, ozone from sunlight reactions with industrial and vehicle emissions, and sulfur dioxide from burning fossil fuels.
• Notably, air pollution is increasing in emerging and industrializing economies while decreasing in advanced economies.
• Nearly 90% of the global population breathes air exceeding recommended limits, with low- and middle-income countries being the worst affected.

Global Concern and WHO Resolution

• Recognizing the global concern over deteriorating air quality, the World Health Assembly Resolution 68.8 in 2015 aimed to address the health impact of air pollution.
• The WHO attributed eight million deaths globally to air pollution, with Delhi being identified as the most polluted city.
• India, along with Afghanistan, Bangladesh, China, and Pakistan, ranked among the top 15 countries with the highest PM2.5 levels.
• The resolution called for cleaner public transit, clean energy sources, and reduced emissions of carbon dioxide, methane, and black carbon.

Air Quality Index (AQI) and Standards

• Measurement of AQI is done through air monitors, and the results are categorized into different ranges.
• The US-EPA AQI has six categories, with “good” air quality ranging from 0-50 and “hazardous” at 301 and above. India’s National Air Quality Index Standard (NAQI) includes six categories, with “severe” representing values of 430 and above.
• In Delhi, PM2.5 levels are about 15 times higher than WHO guidelines.

National Clean Air Programme (NCAP)

• India’s National Clean Air Programme, launched in 2019, aims to reduce PM10 and PM2.5 concentrations by 20-30% by 2024.

• It includes interventions to reduce vehicular pollution, promote public transport, address industrial emissions, manage waste, monitor air quality, and control paddy stubble burning.

Health Impacts

• Air pollution plays a crucial role in the development of chronic diseases and cancer.
• It leads to health consequences such as cancer, cardiovascular disease, respiratory diseases, diabetes, obesity, and various neurological and immune system disorders.
• A significant portion of stroke, lung cancer, and heart disease deaths is attributed to air pollution.

Vulnerability of Children

• Children are particularly vulnerable to air pollution due to their developing lungs, limited ability to detoxify pollutants, and exposure to neurotoxic compounds.
• Babies born to mothers exposed to air pollution during pregnancy are more likely to be premature and have low birth weight.

Social Gradient in Air Quality

Contrary to the belief that air pollution affects everyone equally, studies in the UK and Europe indicate that air quality often exhibits a social gradient, with higher deprivation indices linked to higher pollutant levels. These disparities in exposure lead to differences in morbidity and mortality, highlighting the need for more stringent air quality standards.

Long-Term Measures and Odd-Even Scheme

• While the odd-even scheme has been implemented in Delhi as a temporary measure during severe air pollution conditions, experts believe it may not be a viable long-term solution.

• Studies show limited reductions in PM2.5 and PM1.0 levels with this scheme. Similar experiences from other megacities like Beijing, Jakarta, and Mexico City suggest that air quality is not significantly improved.

One Health Approach and Airshed-Centric Management

• The One Health approach has traditionally focused on infectious diseases but now acknowledges that human, animal, and ecosystem health is directly impacted by land, air, sea, and freshwater use.

• Transitioning from city-centric to airshed-centric air quality management is recommended, acknowledging the impact of local topography and meteorology on pollutant dispersion.

• India’s NCAP should leverage these approaches to address pollution comprehensively.

Conclusion

The growing air pollution crisis in Delhi and India necessitates a multi-pronged approach, including stricter air quality standards, comprehensive policies, and a focus on long-term solutions. Acknowledging the health impacts, especially on children, and transitioning to more holistic approaches like the One Health model and airshed-centric management can contribute to better air quality and public health.