Lifting the ‘constant black cloud’: how a smog-bound city cut dangerous levels of air pollution – The Guardian

 

Report on Air Quality Improvement in Santiago, Chile and its Alignment with Sustainable Development Goals

This report details the significant progress made by Santiago, Chile, in reducing atmospheric pollution. The sustained, multi-decade effort aligns with several key United Nations Sustainable Development Goals (SDGs), particularly those concerning health, sustainable cities, and clean energy.

Progress in Urban Air Quality Management: Achieving SDG 11

Santiago’s long-term strategy to combat air pollution serves as a model for SDG 11 (Sustainable Cities and Communities), specifically Target 11.6, which aims to reduce the adverse per capita environmental impact of cities, including air quality.

Policy Implementation and Outcomes

The city’s success is the result of consistent, long-term policies. Over nearly three decades, the following measures have been implemented:

• Modernization and electrification of the public transportation system.
• Seasonal vehicle restrictions based on license plate numbers to reduce traffic during periods of poor air quality.
• Bans on the use of wood-burning heaters during winter months.
• Suspension of agricultural burning during environmental alerts.

Quantitative Improvements in Air Quality

The policies have yielded measurable results, contributing directly to a healthier urban environment. Recent data indicates:

• A 66% reduction in hours of exposure to high levels of pollution over the last decade.
• The most recent year was the third-best on record for the fewest hours of critical pollution episodes since 1997.
• During the May-August period, there were only 23 critical episodes, a drastic reduction from the 915 hours of critical episodes recorded for the same pollutant in 2015.
• Violations of the wood-burning ban fell by 88% compared to the previous year.

Contribution to Public Health and Well-being (SDG 3)

The reduction in air pollutants like fine particulate matter (PM2.5) has had a direct positive impact on the health of Santiago’s 7.5 million residents, advancing SDG 3 (Good Health and Well-being).

Public Health Impact

Improved air quality has led to tangible health benefits. Residents report fewer cases of respiratory viruses, particularly among children, resulting in fewer hospital visits compared to previous years. This demonstrates a clear link between environmental policy and public health outcomes.

Overcoming Geographical Challenges

Santiago’s progress is particularly noteworthy given its challenging geography. The city is situated in a valley surrounded by the Andes mountains, creating a “pressure cooker” effect that traps pollutants. This is exacerbated by winter temperature inversions, which limit air circulation. The success in mitigating these natural disadvantages underscores the effectiveness of the implemented policies.

Advancing Sustainable Energy and Infrastructure (SDG 7)

The city’s strategy emphasizes a transition towards cleaner energy sources in transportation and housing, in line with SDG 7 (Affordable and Clean Energy).

Modernization of Public Transportation

A key driver of progress has been the electrification of public transport. Currently, 30% of the city’s 9,000-unit bus fleet is electric. This initiative not only reduces peak pollution but also contributes to building sustainable urban infrastructure.

Challenges in Residential Energy Transition

The transition to clean energy in the residential sector faces obstacles. While policies discourage wood-burning, the electrification of home heating and cooking lags due to limited financial support. This highlights the challenge of “energy poverty,” where economic constraints limit the adoption of cleaner, albeit more expensive, technologies, thereby impeding the full realization of SDG 7.

Addressing Climate Action and Future Challenges (SDG 13)

While Santiago has made progress on winter pollution, new challenges linked to climate change are emerging, requiring continued focus on SDG 13 (Climate Action).

Emerging Pollutant Concerns

Experts warn that while winter PM2.5 levels are decreasing, another pollutant—tropospheric ozone—is increasing during the summer. This phenomenon is worsened by the climate crisis, indicating that air quality management must adapt to new environmental realities.

Risk of Public Complacency

A consequence of the improved air quality is the “normalization of pollution.” As severe pollution episodes become less frequent, the issue is no longer a primary topic of public discussion. This complacency could make it more difficult to implement further measures needed to achieve long-term sustainability and climate goals.

Conclusion and Recommendations

Santiago’s success in reducing winter air pollution is a testament to the power of sustained policy and citizen cooperation. It provides a valuable case study for achieving SDGs in a complex urban environment. To build on this momentum, the following actions are recommended:

1. Develop targeted financial support programs to address energy poverty and accelerate the transition to clean residential heating, fully aligning with SDG 7.
2. Launch public awareness campaigns to combat complacency and educate citizens on emerging threats like summer ozone pollution, reinforcing the importance of continued action for SDG 3 and SDG 11.
3. Continue investment in the electrification of both public and private transport to further reduce emissions and advance progress towards SDG 13.

Analysis of SDGs, Targets, and Indicators in the Article

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

The article on Santiago’s efforts to combat air pollution connects to several Sustainable Development Goals (SDGs). The primary focus is on urban environmental quality and public health, but it also touches upon sustainable transport and energy.

• SDG 3: Good Health and Well-being

  This goal is central to the article, as the primary motivation for reducing air pollution is to improve the health of Santiago’s 7.5 million residents. The text explicitly links past high pollution levels to overwhelmed hospitals and current improvements to better health outcomes, such as a resident noticing her daughter had “fewer cases of respiratory viruses.”

• SDG 11: Sustainable Cities and Communities

  The article is a case study in making a city more sustainable. It details Santiago’s long-term policies aimed at improving the urban environment by tackling a major issue: air quality. The discussion revolves around creating a healthier, more livable city through measures like modernizing public transportation and managing pollution sources.

• SDG 7: Affordable and Clean Energy

  This goal is relevant through the discussion of home heating methods. The policy to ban wood-burning heaters is a direct attempt to shift residents towards cleaner energy sources. The article also highlights the challenge of “energy poverty,” where economic factors cause people to revert to polluting fuels like wood, underscoring the need for energy solutions that are both clean and affordable.

• SDG 13: Climate Action

  While not the main focus, this goal is connected. The article mentions that the “climate crisis” worsens the problem of tropospheric ozone in the summer. Furthermore, many of the solutions discussed, such as electrifying public transport and moving away from burning wood, are mitigation measures that reduce greenhouse gas emissions in addition to local air pollutants.

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

Based on the policies and outcomes described, several specific SDG targets can be identified:

1. Target 11.6: Reduce the adverse per capita environmental impact of cities, including by paying special attention to air quality.

   This is the most direct target addressed. The entire article details Santiago’s nearly 30-year effort to reduce the environmental impact of air pollution on its citizens. The policies mentioned—vehicle restrictions, banning wood-burning heaters, and modernizing transport—are all aimed at improving urban air quality for its large population.

2. Target 3.9: Substantially reduce the number of deaths and illnesses from hazardous chemicals and air, water and soil pollution and contamination.

   The article directly supports this target by describing the successful reduction of “critical pollution episodes.” The mention that in the past, “hospitals would be overwhelmed” and the recent observation of a child being “healthier than last winter” with fewer respiratory viruses clearly links the reduction in air pollution to a decrease in related illnesses.

3. Target 11.2: Provide access to safe, affordable, accessible and sustainable transport systems for all.

   This target is addressed through the city’s policy of “modernising and electrifying public transport.” The article states that “30% of a 9,000-unit fleet is now electric,” which is a concrete step towards creating a more sustainable transport system that reduces pollution and serves the city’s residents.

4. Target 7.2: Increase substantially the share of renewable energy in the global energy mix.

   While the article focuses on “clean” rather than “renewable” energy, the principles align. The push to electrify home heating and ban wood-burning heaters is a move away from polluting, inefficient solid fuels towards cleaner energy sources. The challenge of “energy poverty” mentioned in the article directly relates to the need to make these cleaner options accessible and affordable to increase their share in the energy mix for residential heating.

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

Yes, the article provides several quantitative and qualitative indicators that can be used to measure progress:

• Indicator for Target 11.6 & 3.9: Annual mean levels of fine particulate matter (PM2.5).

  The article explicitly focuses on reducing fine particulate matter (PM2.5). It provides several metrics to track this:

  • A 66% fall in “hours of exposure to high levels of pollution” over the last decade.
  • A specific comparison of “critical episodes,” noting there were 23 this year (20 alerts and 3 pre-emergencies) compared to 915 hours of critical episodes in 2015.

• Indicator for Target 11.2: Share of the public transport fleet that is sustainable/electric.

  The article provides a clear metric: “30% of a 9,000-unit fleet is now electric.” This is a direct indicator of progress in modernizing public transport.

• Implied Indicator for Target 7.2: Reduction in the use of polluting fuels for heating.

  Progress is measured by compliance with the ban on polluting heating methods. The article states that “violations of the wood-burning ban fell sharply – 88% lower than in 2024.”

• Other Implied Indicators:

  • Compliance with vehicle restrictions: The article notes that “violations fell nearly 23%, from 1,900 to 1,600 per day,” indicating the effectiveness of the policy.
  • Reduction in agricultural burning: Progress is shown by “a 23.8% reduction in the number of fires and a 77% drop in the burned area.”
  • Public health outcomes: Though anecdotal, the mention of “fewer cases of respiratory viruses” and the historical context of “overwhelmed hospitals” serve as qualitative indicators of improved health due to cleaner air.

4. Table of SDGs, Targets, and Indicators

SDGs	Targets	Indicators
SDG 11: Sustainable Cities and Communities	11.6: Reduce the adverse per capita environmental impact of cities, paying special attention to air quality.	Annual mean levels of fine particulate matter (PM2.5). 66% decrease in hours of exposure to high pollution over a decade. Reduction in critical pollution episodes (23 this year vs. 915 hours in 2015).
SDG 3: Good Health and Well-being	3.9: Substantially reduce the number of deaths and illnesses from air pollution.	(Implied) Reduction in hospitalizations from respiratory illnesses (from “overwhelmed” to manageable). (Anecdotal) Reports of fewer cases of respiratory viruses in children.
SDG 11: Sustainable Cities and Communities	11.2: Provide access to sustainable transport systems for all.	Percentage of public transport fleet that is electric (30% of 9,000 units). 23% decrease in daily violations of vehicle restrictions.
SDG 7: Affordable and Clean Energy	7.2: Increase substantially the share of renewable energy in the global energy mix.	(Implied) Reduction in reliance on polluting heating fuels. 88% decrease in violations of the wood-burning ban.
SDG 13: Climate Action	13.2: Integrate climate change measures into national policies, strategies and planning.	Implementation of policies with climate co-benefits (e.g., transport electrification). 23.8% reduction in agricultural fires and 77% drop in burned area.

Source: theguardian.com