THE CASE FOR ACTION ON TROPOSPHERIC OZONE

The report highlights that tropospheric ozone is a potent greenhouse gas and air pollutant responsible for approximately 0.23°C of present-day warming and nearly 500,000 premature deaths annually. It is not emitted directly but forms from precursors like methane, nitrogen oxides (NOx), non-methane volatile organic compounds (NMVOCs), and carbon monoxide (CO). The document identifies a significant gap in global climate strategies, noting that tropospheric ozone is largely absent from the Paris Agreement and most Nationally Determined Contributions (NDCs). It provides sector-specific policy levers—ranging from methane capture in oil and gas to electric vehicle adoption in transport—and presents case studies from Los Angeles, Mexico City, Beijing, and Europe to demonstrate the effectiveness of targeted pollution control. The report concludes with recommendations for policymakers to adopt multi-pollutant approaches, for scientists to fill knowledge gaps in regional climate effects, and for funders to increase the currently insufficient international development funding for outdoor air pollution.

• Tropospheric ozone is a significant driver of global warming, contributing approximately 0.23°C to present-day temperature increases since 1750.
• The pollutant causes severe public health crises, with nine out of ten people exposed to levels exceeding WHO guidelines, leading to nearly 500,000 premature deaths and $500 billion in annual economic costs.
• Tropospheric ozone reduces global food security by damaging staple crops such as wheat, soybean, and maize; projected economic losses for these crops could reach $35 billion annually by 2030.
• Tropospheric ozone is not directly emitted but is formed by the interaction of sunlight with precursor pollutants: methane, nitrogen oxides (NOx), non-methane volatile organic compounds (NMVOCs), and carbon monoxide (CO).
• There is a critical gap in international climate governance, as tropospheric ozone is not included in the Paris Agreement and is rarely mentioned in Nationally Determined Contributions (NDCs), with exceptions such as Tunisia and Micronesia.
• Reducing super pollutants, including tropospheric ozone, offers a faster route to climate mitigation than decarbonisation alone, potentially mitigating warming nearly four times faster by 2050.
• Case studies show that while cities like Los Angeles and Mexico City achieved significant ozone reductions through targeted precursor controls, progress has recently stalled due to factors like climate-driven heat waves and wildfires.
• International development funding for outdoor air pollution is severely inadequate, receiving less than 1% of all such funding between 2018 and 2022.

APA

Blanco, K. J., Cruzado, A., Espinosa, M., Franco, J. F., Klakamp, J., Lacy, R., Bending, S. M., Betancourt, R. M., Suarez, L. G. R., Sosa, Z. T., Garson, A., Grylls, T., Roy, A., & Hunter, R. (n.d.). THE CASE FOR ACTION ON TROPOSPHERIC OZONE. Clean Air Task Force. https://cdn.catf.us/wp-content/uploads/2024/11/19120324/troposheric-report.pdf

Chicago

Blanco, Karen Johanna, Alberto Cruzado, Mónica Espinosa, Juan Felipe Franco, Juliana Klakamp, Rodolfo Lacy, Stephanie Montero Bending, et al. THE CASE FOR ACTION ON TROPOSPHERIC OZONE. Clean Air Task Force, n.d. https://cdn.catf.us/wp-content/uploads/2024/11/19120324/troposheric-report.pdf.

Wikipedia

{{cite report |last1=Blanco |first1=Karen Johanna |last2=Cruzado |first2=Alberto |last3=Espinosa |first3=Mónica |last4=Franco |first4=Juan Felipe |last5=Klakamp |first5=Juliana |last6=Lacy |first6=Rodolfo |last7=Bending |first7=Stephanie Montero |last8=Betancourt |first8=Ricardo Morales |last9=Suarez |first9=Luis Gerardo Ruiz |display-authors=etal |title=THE CASE FOR ACTION ON TROPOSPHERIC OZONE |publisher=Clean Air Task Force |url=https://cdn.catf.us/wp-content/uploads/2024/11/19120324/troposheric-report.pdf |access-date=23 October 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{blancondcase, author = {Blanco, Karen Johanna and Cruzado, Alberto and Espinosa, Mónica and Franco, Juan Felipe and Klakamp, Juliana and Lacy, Rodolfo and Bending, Stephanie Montero and Betancourt, Ricardo Morales and Suarez, Luis Gerardo Ruiz and Sosa, Zitely Tzompa and Garson, Anna and Grylls, Tom and Roy, Arindam and Hunter, Ross}, title = {{THE CASE FOR ACTION ON TROPOSPHERIC OZONE}}, institution = {Clean Air Task Force}, url = {https://cdn.catf.us/wp-content/uploads/2024/11/19120324/troposheric-report.pdf}, urldate = {2026-10-23}, note = {Indexed by Climate Insights Directory} }