Clean Air Coalition Research Articles

The politics of knowledge in black carbon mitigation: Policy entrepreneurship of Finnish actors and the Climate and Clean Air Coalition

Mitigation of black carbon (BC) is a potent short-term measure for climate and environmental policy due to the short lifetime of BC particles in the atmosphere. Fewer BC emissions would decelerate warming especially in the Arctic and bring significant co-benefits particularly in populous countries owing to BC’s negative public health, food security and socio-economic effects. However, scientific knowledge on BC remains uncertain regarding the measurement, monitoring and precise effects of BC while the respective global policy framework is fragmented. To address this situation, we scrutinize the science/policy nexus in BC mitigation on the regional level where some promising openings exist. For this end, our new analytical framework focuses on policy entrepreneurs, their interests and cognitive frames, and the structural environment. Utilising content analysis of expert interviews and document data, three cases are covered with significant policy entrepreneurship on BC. First, we examine Finland ‘s high-profile BC initiative, finding it to frame BC pollution as an Arctic climate threat. Second, Finland’s research, development and innovation cluster, which has substantial expertise on air pollution, frames BC as a public health hazard, and scopes prospects for policy frameworks helping to open markets for mitigation technologies and solutions. Third, the Climate and Clean Air Coalition approaches BC with a wide multipollutant frame, driven by broad socio-economic and developmental interests. The Finnish initiative’s potential is found to suffer from insufficient coordination with the RDI cluster. Both Finland’s BC specific and the CCAC’s wider multipollutant frame can in different ways contribute to abatement.

The UNEA 6 Resolution on Air Quality acknowledges the Integrated Assessment of Air Pollution and Climate Change for Sustainable Development in Africa

In a major boost to air quality and sustainable development in Africa, a new UNEA 6 Resolution on Air Quality has acknowledged the Integrated Assessment of Air Pollution and Climate Change for Sustainable Development in Africa. The new development came in 2023, when the Integrated Assessment of Air Pollution and Climate Change for Sustainable Development in Africa (UNEP, 2023), was published by a partnership of the African Union, Climate and Clean Air Coalition and the United Nations Environment Programme. The assessment was developed with contributions from over 100 authors across Africa, in a process supported by the Stockholm Environment Institute (Kaudia et al. 2022). The Assessment recommended for an Africa Clean Air Program (ACAP) to provide a key rallying point for African multilateral institutions, the Regional Economic Communities (RECs) and Member States, and development partners to work collaboratively to implement the recommendations from the assessment and deliver multiple benefits of clean air for Africa.

Ocean-based Climate Action and Human Rights Implications under the International Climate Change Regime

Abstract After drawing attention to the crucial role of marine biodiversity, including that of deep-sea ecosystems, in current scientific understanding of the ocean-climate nexus, this article highlights the limited extent to which the international climate change regime has so far addressed the ocean. The focus then shifts to how the international climate change regime could contribute to the protection of marine biodiversity as part of mitigation, adaptation and finance, taking into account human rights impacts and standards, drawing a comparison with REDD+. The article concludes with an original proposal, inspired by the Climate and Clean Air Coalition, to develop urgent, synergistic approaches to ocean- and human rights-based climate action through a multi-actor coalition, including different international treaties and United Nations bodies, to ‘protect and restore the ocean’s contributions to climate regulation, human well-being and planetary health’.

Learning by Doing: Co-Benefits Drive National Plans for Climate and Air Quality Governance

What drives countries to realize more integrated policymaking? The co-benefits concept highlights the win–win situations that can arise if one policy measure addresses two or more policy goals, e.g., air quality and health benefits resulting from a climate policy. Scholars have suggested that decision makers, if confronted with the evidence of co-benefits, would update their beliefs and adopt stronger or more ambitious climate policies. In other words, a learning process takes place. This paper looks at the policy processes in two countries, Mexico and Nigeria, as part of the Supporting National Action and Planning (SNAP) initiative under the Climate and Clean Air Coalition (CCAC). The SNAP initiative supports governments with policymaking and implementation for a reduction in short-lived climate pollutants (SLCPs). This paper seeks to reveal how learning processes and their outcomes are influenced by co-benefits as a specific type of information. Looking at an example of how the co-benefits concept is applied in political practice offers valuable insights into how learning is part of the policymaking process and can shape its outcomes, such as national (climate) action plans.

Preparing the playing field: climate club governance of the G20, Climate and Clean Air Coalition, and Under2 Coalition

International climate policy is increasingly shaped by alternative forms of governance. Coalitions of national, subnational, and/or non-state actors have the potential to address the global challenge of climate change beyond the United Nations Framework Convention on Climate Change (UNFCCC) process. While initially such “clubs” spurred hope that they could be an option to achieve climate action more effectively than the UNFCCC, more recently, their role has been seen as preparing and orchestrating climate policy. In spite of its conceptual proliferation, literature on climate clubs stops short in examining practical evidence and conducting analyses beyond categorization and labelling of climate clubs. This article aims at contributing to filling this gap with a comparative perspective on three specific governance initiatives that act on different governance levels: the G20, the Climate and Clean Air Coalition (CCAC), and the Under2 Coalition. What contribution do these club-like initiatives make to global climate governance and how does it relate to existing structures such as the Paris Agreement and the UNFCCC process? Our paper applies central aspects of clubs research, namely, membership, public goods, and the provision of additional benefits as an analytical framework to examine the three cases. We find that these club initiatives, though highly diverse in their origin and membership, make a similar contribution to international climate governance. Their largest contribution lies in preparing emissions reductions through raising awareness, orchestrating different actors and actions, and establishing a large cooperation network. They complement the UNFCCC and especially the Paris Agreement.

Quantification of climate change mitigation potential at Novi Sad landfill

Unsanitary landfills and inadequate waste management system represent the 3rd largest global anthropogenic source of methane emissions in the environment. Waste management system in Novi Sad, the second largest city in Serbia, significantly contributes to the national carbon footprint. Unsanitary Municipal solid waste landfill in Novi Sad receives and deposits mixed waste without any treatment, thus causing the organic waste to biodegrade within the landfill body, and produce and emit the landfill gas (mostly CH4 and CO2) in the environment. Other potential sources of greenhouse gas emissions from waste management system include vehicles used for waste collection, machinery used at the landfill and landfill fires. The purpose of this study is to determine total baseline emissions of relevant greenhouse gases from the waste management system in Novi Sad, and to estimate and quantify the emission reduction potential for defined organic waste treatment scenario. The potential scenarios for organic waste diversion and treatment from the landfill include composting, anaerobic digestion, mechanical biological treatment, waste to energy, etc. Quantification of baseline emissions and climate change mitigation potential are estimated using the Solid Waste Emissions Estimation Tool, the model developed by Climate and Clean Air Coalition.

Facility level measurement of offshore oil and gas installations from a medium-sized airborne platform: method development for quantification and source identification of methane emissions

Abstract. Emissions of methane (CH4) from offshore oil and gas installations are poorly ground-truthed, and quantification relies heavily on the use of emission factors and activity data. As part of the United Nations Climate & Clean Air Coalition (UN CCAC) objective to study and reduce short-lived climate pollutants (SLCPs), a Twin Otter aircraft was used to survey CH4 emissions from UK and Dutch offshore oil and gas installations. The aims of the surveys were to (i) identify installations that are significant CH4 emitters, (ii) separate installation emissions from other emissions using carbon-isotopic fingerprinting and other chemical proxies, (iii) estimate CH4 emission rates, and (iv) improve flux estimation (and sampling) methodologies for rapid quantification of major gas leaks. In this paper, we detail the instrument and aircraft set-up for two campaigns flown in the springs of 2018 and 2019 over the southern North Sea and describe the developments made in both the planning and sampling methodology to maximise the quality and value of the data collected. We present example data collected from both campaigns to demonstrate the challenges encountered during offshore surveys, focussing on the complex meteorology of the marine boundary layer and sampling discrete plumes from an airborne platform. The uncertainties of CH4 flux calculations from measurements under varying boundary layer conditions are considered, as well as recommendations for attribution of sources through either spot sampling for volatile organic compounds (VOCs) ∕ δ13CCH4 or using in situ instrumental data to determine C2H6–CH4 ratios. A series of recommendations for both planning and measurement techniques for future offshore work within marine boundary layers is provided.

A Conversation

A Conversation

El cosmopolitismo urbano: la ciudad ante el orden postliberal

El artículo estudia la sucesión de cambios en la estructura política internacional ante la reconfiguración de las fuentes de poder. Establece tres vertientes en las bases teóricas del cosmopolitismo urbano. La primera indica cuáles deberían ser los fundamentos de una elaboración teórica. La ciudad internacional contribuye a la reconfiguración de la estructura y el ejercicio del poder interestatal ocupando o creando nuevos espacios que contribuyen a la pluralidad de las Relaciones Internacionales. El segundo aspecto que se analiza es el crecimiento de la ciudad como unidad de medida en la economía global. Los flujos de capital circulan y operan sobre una base local con destinos globales. Son las ciudades y sus extensiones metropolitanas quienes se benefician del sistema económico. Aparecen grandes bolsas de desigualdad interna y, sobre todo, con una ruptura entre ciudades dentro y fuera del orden económico, incluyendo aquí la desigualdad relacional que se genera en los territorios menos poblados. Por último, se incide en la razón antropocénica, esto es, el impacto de la acción humana en las condiciones naturales y sus consecuencias en el orden mundial. El cambio climático cambia el sustrato principal de las Relaciones Internacionales, que es el medio físico y la geografía. Sobre estas dos dimensiones tangibles, se ordenan las bases del poder y la teoría básica de los estudios internacionales. Al cambiar el tablero estratégico, la ciudad conquista posiciones de poder no coercitivo, lo que facilita la colaboración mediante redes y estructuras. El aspecto militar y de seguridad no es relevante para la diplomacia urbana, que se centra en aspectos de poder económico y social. Los resultados indican que el nuevo cosmopolitismo tiene bases urbanas y ofrece un marco de interpretación de las tensiones entre centro y periferia de la acción exterior, la globalización económica y las nuevas políticas públicas en la lucha contra el cambio climático. El cosmopolitismo urbano emerge como referencia teórica en el orden postliberal.

A club\u2019s contribution to global climate governance: the case of the Climate and Clean Air Coalition

Not only is the climate changing, but so is global climate governance. Climate policy initiatives have proliferated within and beyond the United Nations Framework Convention on Climate Change (UNFCCC) regime in a polycentric pattern. Nevertheless, promised action under the Paris Agreement (PA) is far from being sufficient to achieve its targets of keeping global warming below 2 °C. A special research focus has emerged on international ‘climate clubs’, referring to a smaller group’s greater ability to make progress in international climate policy compared to large global forums. Against this background, our paper reflects on the club functions of the Climate and Clean Air Coalition (CCAC), a transnational partnership that aims at slowing the rate of near-term global warming through the reduction of short-lived climate pollutants (SLCPs). How does the CCAC contribute to global climate governance and how does this relate to existing structures, such as the UNFCCC process and the PA? Researchers have generally found that climate clubs can raise ambition, produce emissions reductions, and/or enhance cooperation, while generating additional benefits for its members. However, their specific governance contribution remains rather opaque, for example, how emissions reductions are achieved. There is a lack of analytical application, knowledge of the political practice and of in-depth case studies of the clubs concept. This paper contributes to filling this gap by applying central aspects of clubs research, namely membership and size, public goods, and the provision of additional benefits as an analytical framework in one in-depth case study of a governance initiative that has not yet been the subject of academic scrutiny: the CCAC. The results are based on expert interviews and the analysis of strategic and academic documents. Overall, this research finds that the CCAC’s largest contribution to global climate governance lies in preparing SLCP emissions reductions through raising awareness, orchestrating different actors and actions related to SLCPs, and establishing a large technical cooperation network. To some degree it also directly implements SLCP reduction projects. Ultimately, it complements the UNFCCC and especially the Paris Agreement. Members are part of the CCAC because its benefits go beyond climate change mitigation. Its large transnational membership constellation both supports and challenges its governance contribution.

A Maritime Emission Control Area for the Mediterranean Sea? Technological Solutions and Policy Options for a ‘Med ECA’

Proposals to create a maritime Emission Control Area for the Mediterranean (‘Med ECA’) are on the agendas of national governments, local governments, port authorities, international organizations, and nongovernmental organizations. Previous studies have contributed much data and analysis about maritime emissions and their impacts in the Mediterranean region. The present paper reviews the results of these studies and evidence from existing ECAs in other regions in order to inform analyses of issues regarding the design and implementation of a Med ECA. There are diverse issues and options concerning technologies and policies that need to be addressed. The potential for applying remote sensing technology and digital ledger technology to compliance verification and enforcement processes is assessed. The following international institutions are especially appropriate for addressing these issues and facilitating the development of a Med ECA: the International Maritime Organization and its affiliated body the Regional Marine Pollution Emergency Response Centre for the Mediterranean Sea, the Climate and Clean Air Coalition at the UN Environment Programme, the World Bank, and the UN Conference on Trade and Development, which prepares an annual review of maritime transport that includes information about recent policy and technology developments. The paper concludes that the public health, food production, climate change and economic benefits of a Med ECA would be significant for the more than 200 million people living in Mediterranean coastal areas.

Reduction of greenhouse gases (GHGs) and short-lived climate pollutants (SLCPs) from municipal solid waste management (MSWM) in the Philippines: Rapid review and assessment

Municipal solid waste management (MSWM) is considered one of the serious environmental issues in the Philippines, with corresponding linkages to the climate change and Sustainable Development Goals (SDGs). However, methane (CH4) linked with indiscriminate dumping of municipal solid waste has received the much attention with regard to public health and climate change. The impacts of black carbon (BC) are less documented and understood. This paper aims to review the status of MSWM in the Philippines and makes efforts to assess the scale of short-lived climate pollutants (SLCPs), including both CH4, and BC, associated with the country’s waste sector. Utilising available national level data and following a life-cycle assessment (LCA) approach, the paper offers preliminary projections of SLCP emissions resulting from present MSWM practices. In addition, it examines model mitigation scenarios based on priority actions identified within the country’s national policy on waste management, Republic Act 2003 (RA 9003). Data analysis was conducted using an Emission Quantification Tool (EQT) developed by the Institute for Global Environmental Strategies (IGES) through its work under the Climate and Clean Air Coalition (CCAC) – Municipal Solid Waste Initiative (MSWI). Following a summary of key findings, the paper affirms that control of methane from disposal practices and of BC from waste collection and open burning requires urgent attention in the Philippines. Continued awareness raising, institutionalising regulatory policies on SLCPs, and further enhancing data collection and capacity building on waste-related BC emissions remain key priorities for the country.

Incomplete cooperation and co-benefits: deepening climate cooperation with a proliferation of small agreements

Case study and model results lend some optimism for the potential of small coalitions with partially excludable public goods to substantially deepen international cooperation on energy and climate issues. Drawing motivation from other issue areas in international relations ranging from nuclear non-proliferation, transboundary air pollution and liberalized trade, we use an evolutionary-game-theoretic model to analyze regimes that yield domestic incentives to contribute to public goods provision (co-benefits). Co-benefits may be limited, but can create a nucleus for formation of coalitions that grow while deepening provision of global public goods. The Climate and Clean Air Coalition (CCAC) is a prime example of an agreement that employs partially excludable club benefits to deepen cooperation on non-CO2 greenhouse gases. Our game-theoretic results support two important insights for the building blocks approach to addressing climate change: sustained cooperation in club agreements is possible even when public goods are not entirely excludable and some members of the population free-ride; and second, cooperation in small club configurations yields larger non-excludable public goods benefits than cooperation in more inclusive forums. This paper lends positive support that a proliferation of small agreements under a building blocks approach at the UNFCCC may be more effective (not just more likely) for deepening climate change cooperation than a fully inclusive approach.

Incomplete Cooperation and Co-Benefits: Deepening Climate Cooperation with a Proliferation of Small Agreements

Case study and model results lend some optimism for the potential of small coalitions with partially excludable public goods to substantially deepen international cooperation on energy and climate issues. Drawing motivation from other issue areas in international relations ranging from nuclear non-proliferation, transboundary air pollution and liberalized trade, we use an evolutionary-game-theoretic model to analyze regimes that yield domestic incentives to contribute to public goods provision (co-benefits). Co-benefits may be limited, but can create a nucleus for formation of coalitions that grow while deepening provision of global public goods. The Climate and Clean Air Coalition (CCAC) is a prime example of an agreement that employs partially excludable club benefits to deepen cooperation on non-CO2 greenhouse gases. Our game-theoretic results support two important insights for the building blocks approach to addressing climate change: sustained cooperation in club agreements is possible even when public goods are not entirely excludable and some members of the population free ride; and second, cooperation in small club configurations yields larger non-excludable public goods benefits than cooperation in more inclusive forums. This paper lends positive support that a proliferation of small agreements under a building blocks approach at the UNFCCC may be more effective (not just more likely) for deepening climate change cooperation than a fully inclusive approach.

Methane emissions from oil and gas transport facilities – exploring innovative ways to mitigate environmental consequences

Climate change impacts are increasingly becoming more evident e.g. through heavy rainfall episodes and subsequent flooding. Methane is a significant greenhouse gas that has been linked to these impacts and the oil and gas industry is a major source of anthropogenic methane emission. Recent studies have suggested that the tropical region hold some unexpectedly high methane concentration and that the recent changes in the global methane burden are poorly understood. To address this research gap, we present a first effort to quantify methane emissions from one of the most vulnerable oil and gas infrastructures in Nigeria (a tropical country). A combination of the Intergovernmental Panel on Climate Change tier-1 approach and an adapted Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation model was used to estimate methane emissions from the system 2C transport pipeline. We then tested the hypothesis of no significant change in methane emissions trend from the pipeline using the between group t-test inferential analysis. Key findings include: (a) a crude oil throughput of 55,143 to 1,500,500 barrels (8767 to 238,561 m3) emitted methane ranging from 0.04734 to 1.288MT (± 50 to 200%) respectively, and (b) surprisingly, methane emissions along the system 2C pipeline seem to have continued without significant change between 2005, and 2008 to 2012 despite the low crude oil throughput in 2009. This indicates the likelihood of continuous but rising methane emissions from the pipeline network over a six-year period; and only further research can ascertain if similar trend can be observed elsewhere in the tropical region. These findings are unique and contribute to the current global debate on methane emissions from the largely unmonitored tropical region. Therefore, we recommend that stakeholders should set up a study plan for the identification and continuous monitoring of methane emissions from the key oil and gas infrastructure and explore opportunities for geoengineering applications as part of climate change mitigation. Coordinated engagement in international schemes such as the Natural Gas STAR program, Climate and Clean Air Coalition, Global Methane Initiative amongst others would promote strategic and measurable methane reduction plans in Nigeria and other countries within/outside the tropical region.

Russian policy on methane emissions in the oil and gas sector: A case study in opportunities and challenges in reducing short-lived forcers

Methane is a potent greenhouse gas, 21 times as powerful as carbon dioxide in contributing to climate change on a ton-for-ton basis. Methane, along with other short-lived forcers such as black carbon and tropospheric ozone, could play an important role in addressing global climate change. This stems both from their overall effect on climate systems, and from their concentrated impact in the short term. Because reducing emissions of such short-lived pollutants may have a large near-term impact in slowing climate change, the United States and other countries have come together to cooperate under the Climate and Clean Air Coalition to Reduce Short-Lived Climate Pollutants, and other partnerships such as the Global Methane Initiative. For global impact, the success of such partnerships depends on their ability to scale up project-specific emission reductions.This paper assesses options and challenges for scaling based on a case study of Russia's oil and gas sector. We examine the challenges to achieving far-reaching emission reductions, successes of companies to date, how Russia has sought to influence methane emissions through its environmental fine system, and options for helping companies achieve large-scale emission reductions in the future through simpler and clearer incentives.

Modernizing Artisanal Brick Kilns: A Global Need

The city of Cusco in southeastern Peru is a World Heritage Site and a tourist attraction for those drawn by the Inca ruins nearby. But anyone who lives in or visits Cusco has to contend with its heavily polluted air. Trucks and buses belch clouds of diesel exhaust, and on the outskirts of town hundreds of family-run artisanal brick kilns send plumes of oily black smoke into the sky. Brick makers near Cusco fire their traditional kilns mainly with coal, but they also have a long history of burning plastic trash, used motor oil, and discarded tires. “They produce huge air quality problems,” says Jon Bickel, a Swiss development expert based in Lima. Most of the bricks that are made in Peru and other low-income countries are fired in artisanal kilns that pump greenhouse gases and other pollutants into the atmosphere, posing a health threat to brick workers, their surrounding communities, and even farther afield. And since brick production keeps pace with population growth, its environmental health impacts are likely growing throughout the developing world, says Jie Li, an energy and environmental specialist with the World Bank’s South Asia Region in Washington, DC. Workers cut firewood to light a brick kiln in Kabul, Afghanistan. The few health studies that have been conducted on kiln workers typically reveal musculoskeletal effects and health effects similar to those seen in other smoky, dusty occupations. A number of both small-scale and multinational development groups coordinated by the World Bank, the United Nations, and other organizations are now turning their attention to this important but poorly characterized industrial sector. Leading the charge in Latin America, Bickel directs a Swiss-funded group known by its Spanish acronym, EELA (for Eficiencia Energetica en Ladrilleras Artesanales) that aims to modernize artisanal brick making in Peru, Argentina, Brazil, Bolivia, Ecuador, Colombia, Nicaragua, Honduras, and Mexico. Bickel says EELA’s long-term goal is to reduce kiln emissions by 30–50%. But achieving that goal won’t be easy. Throughout Latin America and other countries in the developing world, artisanal kiln operators comprise an informal industry; they rarely pay taxes or obtain operating permits, and because of that, they often lack access to the financial credit and capital needed to purchase cleaner technology. Many also lack electricity (required for newer types of mechanized production) and access to roads and other infrastructure that could help in the modernization effort. Some are unwilling to change age-old manufacturing processes. Pakistani families prepare bricks at a fixed-chimney Bull’s trench kiln on the outskirts of Islamabad. Under debt bondage, an entrenched custom in South Asia, families can work at kilns for years paying off loans from the owners. Still, the associated benefits of modernization justify the effort, Li says. In addition to the environmental health impacts associated with artisanal brick kilns, these operations employ “the poorest of the poor, including, in many instances, women and children,” Li says. “So by promoting more efficient kilns and manufacturing, we can also address related development problems, such as poverty, child labor, and women’s issues.”

17. New Zealand

In 2012, New Zealand announced its decision not to sign up to a second commitment period under the Kyoto Protocol but, instead, to set its emission reduction target under the United Nations Framework Convention on Climate Change (UNFCCC). New Zealand also joined the Climate and Clean Air Coalition, began a joint study with South Korea to investigate linking the two countries’ emissions trading schemes, and decided to fund a solar plant in the Islamic Republic of Afghanistan. At the United Nations Conference on Sustainable Development (Rio + 20), New Zealand focused upon improving the environmental management of oceans and fossil fuel subsidy reform, signed up to the global partnership on oceans, and supported Australia’s launch of the World Indigenous Network. New Zealand and the United States submitted a joint proposal for a Ross Sea marine protected area at the annual Commission for the Conservation of Antarctic Marine Living Resources...

Media Activism: Bantay Kalikasan in the Passage of the Clean Air Act

This case study examines the role of media in the enactment of the Clean Air Act of 1999 (CAA). Through the intervention of the Bantay Kalikasan (Nature Watch), the environmental advocacy arm of ABS-CBN (the largest broadcasting network of the Philippines), the clean air discourse became a public issue. It not only campaigned actively for the law by initiating roadside information teams, but it also initiated the 5M–signature campaign in support of the CAA’s enactment into law. Most of all, it amplified the discursive health and moral debates popularized by the Clean Air coalition concerning incinerator. Environment is not exactly a mainstream issue in the Philippines, but the media possess the essential resources to make any dire environmental issue a public concern. As soon as the media realize their discursive power to popularize any technical environmental concern, the more realizable the future will be for a more viable and more continuous environmental policy not only for clean air.

Media Activism: Bantay Kalikasanin the Passage of the Clean Air Act

This case study examines the role of media in the enactment of the Clean Air Act (CAA) of 1999. Through the intervention of the Bantay Kalikasan (Nature Watch), the environmental advocacy arm of the ABS-CBN, the largest broadcasting network of the Philippines, the clean air discourse became a public issue. It not only campaigned actively for the law by initiating roadside information teams, but it also initiated the 5M–signature campaign in support of the CAA’s enactment into law. Most of all, it amplified the discursive health and moral debates popularized by the Clean Air coalition concerning incinerators. Environment is not exactly a mainstream issue in the Philippines, but the media possess the essential resources to make any dire environmental issue a public concern. As soon as the media realize their discursive power to popularize any technical environmental concern, the more realizable the future will be for a more viable and more continuous environmental policy not only for clean air.