Report on Urban Air Pollution Patterns in India and Implications for Sustainable Development Goals

Introduction: Air Pollution as a Barrier to Sustainable Development

Air pollution represents a critical global challenge, directly impeding progress towards multiple Sustainable Development Goals (SDGs). As the second leading health risk globally in 2021, it poses a significant threat to SDG 3 (Good Health and Well-being). The situation is particularly acute in India, where rapid urbanisation challenges the targets of SDG 11 (Sustainable Cities and Communities). In 2019, air pollution was linked to 1.67 million deaths in the country, constituting nearly 18% of total fatalities. This report analyses recent research on urban pollution distribution across India, highlighting its complex nature and the need for revised mitigation strategies aligned with the 2030 Agenda for Sustainable Development.

Analysis of Urban Aerosol Islands in India

A comprehensive study conducted by the Indian Institute of Technology (IIT) Bhubaneswar provides new insights into the phenomenon of “urban pollution islands,” where aerosol concentrations differ between urban centres and their surrounding non-urban areas. The findings reveal a significant geographical divergence in these patterns across India.

Methodology and Scope

The research was based on an analysis of satellite data collected over 141 Indian cities between 2003 and 2020. The primary metric used was Aerosol Optical Depth (AOD), which measures the concentration of atmospheric aerosols and serves as a proxy for air pollution levels.

Key Findings: A North-South Dichotomy

The study identified two distinct and opposing patterns of urban pollution distribution, with profound implications for achieving SDG 11:

• Urban Aerosol Pollution Islands (UAPIs): In many cities across southern and southeastern India, aerosol levels were found to be higher directly over urban areas compared to their surroundings. This indicates that locally generated pollution is the dominant factor, becoming trapped over the city.
• Urban Aerosol Clean Islands (UACIs): Conversely, cities in the northern Indo-Gangetic Plain (IGP) frequently exhibit a counterintuitive pattern where the air within the city is relatively cleaner than the highly polluted surrounding region. It is critical to note that a UACI designation does not imply clean air in absolute terms; rather, it signifies that the extreme pollution in the surrounding rural and semi-urban areas exceeds that within the city’s core. The absolute pollution levels in these cities remain a severe threat to SDG 3.

Drivers of Pollution Patterns and Implications for SDGs

The Urban Wind-Stilling Effect

The formation of both UAPIs and UACIs is largely attributed to the “urban wind-stilling effect,” where dense urban infrastructure slows down wind speeds. This phenomenon acts as a barrier with a dual effect:

1. In southern cities with lower background pollution, the barrier traps locally generated emissions, creating a UAPI.
2. In northern cities, which are situated in a region with high background pollution, the same barrier impedes the entry of external pollutants, resulting in a UACI.

The Critical Role of Regional Pollutants

The research underscores the dominant influence of regional and long-range transported aerosols, especially dust from sources like the Thar Desert. This high level of background pollution in the IGP is the primary driver of the UACI effect. This finding links urban air quality directly to broader environmental management, including efforts related to SDG 15 (Life on Land), as land degradation and desertification can exacerbate regional dust events. Furthermore, understanding these aerosol loading patterns is vital for climate science and achieving SDG 13 (Climate Action), as they significantly impact urban climate, temperature, and precipitation.

Conclusion and Policy Recommendations for Achieving SDGs

The study’s primary conclusion is that city-centric air pollution mitigation strategies are insufficient for India. The significant contribution of regional and transported pollutants necessitates a broader, more integrated approach.

Strategic Recommendations

To effectively combat air pollution and advance the Sustainable Development Goals, the following strategic shifts are recommended:

1. Adopt a Regional Mitigation Framework: Policies must transcend municipal boundaries to address transboundary pollution from sources like dust and biomass burning. This requires enhanced cooperation between state and local governments, embodying the principles of SDG 17 (Partnerships for the Goals).
2. Integrate Air Quality into Urban and Regional Planning: The findings challenge conventional urban planning. To build truly sustainable cities under SDG 11, planners must account for regional pollution dynamics and the barrier effects of urban morphology.
3. Enhance Monitoring and Research: Continued investment in research is needed to understand the complex interplay between local emissions, regional transport, and urban climate. This knowledge is fundamental to designing effective interventions that protect public health (SDG 3) and promote climate resilience (SDG 13).

Analysis of Sustainable Development Goals in the Article

1. Which SDGs are addressed or connected to the issues highlighted in the article?

   • SDG 3: Good Health and Well-being

     The article directly connects to this goal by framing air pollution as a major health crisis. It opens by calling it a “silent, invisible killer” and states that in 2021, it was the “second deadliest health risk globally.” The specific impact on India is quantified with the statistic that “air pollution was responsible for approximately 1.67 million deaths in India” in 2019.

   • SDG 11: Sustainable Cities and Communities

     This is a central theme of the article. The entire study focuses on air pollution patterns within urban environments, discussing “Urban Aerosol Pollution Islands (UAPIs)” and “Urban Aerosol Clean Islands (UACIs).” The article highlights the challenge of “rapid urbanisation” in India and concludes by emphasizing that understanding these pollution patterns is vital for creating “healthier and more sustainable cities for everyone.”

   • SDG 13: Climate Action

     The article establishes a link to climate action by noting that aerosol loading patterns have broader environmental consequences. It states that understanding these patterns is “vital for predicting their impact on urban climate, temperature, and even rainfall.” This connects the issue of air pollution directly to local and regional climate phenomena.

   • SDG 15: Life on Land

     This goal is relevant due to the article’s identification of regional pollution sources. It explicitly mentions that pollution is influenced by “dust storms from the Thar Desert or smoke from biomass burning.” These sources are related to land use, land degradation, and desertification, which are key concerns of SDG 15.

2. What specific targets under those SDGs can be identified based on the article’s content?

   • Target 3.9: By 2030, substantially reduce the number of deaths and illnesses from hazardous chemicals and air, water and soil pollution and contamination.

     The article’s core focus on the mortality caused by air pollution aligns perfectly with this target. The mention of “1.67 million deaths in India” due to air pollution directly addresses the problem that this target aims to solve.

   • Target 11.6: By 2030, reduce the adverse per capita environmental impact of cities, including by paying special attention to air quality and municipal and other waste management.

     The study’s investigation into urban air quality, using Aerosol Optical Depth (AOD) to measure pollution levels in 141 Indian cities, is a direct examination of the environmental impact of cities, with a special focus on air quality as mandated by this target.

   • Target 11.b: By 2020, substantially increase the number of cities and human settlements adopting and implementing integrated policies and plans towards inclusion, resource efficiency, mitigation and adaptation to climate change, resilience to disasters…

     The article’s conclusion strongly advocates for this target. It criticizes “city-centric” efforts and calls for “synergistic regional and local measures to mitigate aerosol pollution,” which is a form of integrated policy and planning for mitigation.

   • Target 15.3: By 2030, combat desertification, restore degraded land and soil, including land affected by desertification, drought and floods, and strive to achieve a land degradation-neutral world.

     This target is relevant because the article identifies “dust storms from the Thar Desert” as a significant contributor to regional pollution. Combating desertification, as per this target, would be a crucial long-term strategy to reduce this source of aerosol pollution.

3. Are there any indicators mentioned or implied in the article that can be used to measure progress towards the identified targets?

   • Indicator for Target 3.9: Mortality rate attributed to ambient air pollution (Indicator 3.9.1).

     The article explicitly provides data for this indicator by stating that air pollution caused “approximately 1.67 million deaths in India, accounting for nearly 18% of the country’s total fatalities that year.”

   • Indicator for Target 11.6: Annual mean levels of fine particulate matter (e.g. PM2.5 and PM10) in cities (Indicator 11.6.2).

     The article uses a specific scientific proxy for this indicator. The study “analysed satellite data… primarily used Aerosol Optical Depth (AOD) data, a measurement… that essentially tells us how much sunlight is blocked by tiny particles (aerosols) in the atmosphere.” AOD is presented as the key metric for measuring air pollution concentration in cities throughout the article.

   • Indicator for Target 11.b: Existence of integrated regional and local mitigation strategies.

     While not a formal UN indicator, the article implies this as a measure of progress. The text points out that “Current efforts in India are often city-centric” and then “strongly advocates for synergistic regional and local measures.” The adoption of such integrated strategies would be a direct indicator of progress based on the article’s recommendations.

   • Indicator for Target 15.3: Proportion of land that is degraded over total land area (Indicator 15.3.1).

     This indicator is implied. The article identifies “dust storms from the Thar Desert” as a major pollution source. The frequency and intensity of these dust storms, which are a result of land degradation and desertification, serve as an indirect measure of the problem described in Target 15.3 and its impact on air quality.

4. Table of SDGs, Targets, and Indicators

   SDGs	Targets	Indicators Identified in the Article
   SDG 3: Good Health and Well-being	Target 3.9: Substantially reduce deaths and illnesses from air pollution.	Mortality rate from air pollution: The article cites “1.67 million deaths in India” in 2019 due to air pollution.
   SDG 11: Sustainable Cities and Communities	Target 11.6: Reduce the adverse per capita environmental impact of cities, paying special attention to air quality.	Aerosol Optical Depth (AOD): The study uses AOD as a primary measure of air pollution levels in 141 Indian cities.
   SDG 11: Sustainable Cities and Communities	Target 11.b: Increase the number of cities implementing integrated policies for mitigation.	Existence of integrated regional and local mitigation strategies: The article advocates for these as a necessary shift from current “city-centric” policies.
   SDG 15: Life on Land	Target 15.3: Combat desertification and restore degraded land.	Impact of land degradation: Implied through the identification of “dust storms from the Thar Desert” as a major regional pollution source.

Source: researchmatters.in