Framing
The ozone layer protects all life on Earth by absorbing ultraviolet radiation produced by the Sun before it reaches Earth's surface. It prevents adverse health and environmental impacts, such as increased rates of skin cancer, cataracts, and ecosystem damage. Beginning in the mid-20th century certain chemicals now known as ozone-depleting substances (ODSs, including chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs)) began to be manufactured in large quantities for industrial and consumer use. Triggered by UV light, these chemicals cause catalytic reactions that deplete stratospheric ozone. The international Montreal Protocol on Substances that Deplete the Ozone Layer established phase-out schedules for ODS production and consumption. 197 countries, including the United States, have signed onto the Montreal Protocol and successfully reversed the global trends in ozone layer depletion through the phaseout of ODSs. The protocol is enforced in California by the US EPA through the Clean Air Act Title VI. The Kigali Amendment to the protocol added phase-out schedules for HFCs.
Policy spotlight
* The US Clean Air Act Title VI of 1990 established limits on the production and import of ODS and authorized the EPA to create and enforce an ODS phaseout plan. * CA SB 605 of 2014 directed CARB to develop a comprehensive strategy to reduce HFC emissions, and SB 1383 of 2016 directed CARB to approve and begin implementing this strategy. SB 1383 also established a target to reduce HFC emissions by 40% below 2013 levels by 2030.
Justice lens
* Depletion of the ozone layer impacts all people across the globe. However, production and consumption of ODSs have historically occurred primarily in developed countries. In recognition of this, the Montreal Protocol established different phaseout timelines for developed and developing countries, with more time allotted to developing countries with low rates of ODS consumption. The Montreal protocol also established a multilateral fund to provide financial assistance for developing countries to meet the phaseout requirements. Additionally, it established committees and panels (MCTOC, MBTOC, TEAP) which provide assistance and technical expertise on phasing out ODSs and introducing newer compounds.
Source & citation
Content on this page draws from The California Doughnut Snapshot and Report, used under CC-BY 4.0.
Aritza, A. and Kraus-Polk, J. et al. (2025). The California Doughnut Snapshot and Report. Zenodo. https://doi.org/10.5281/zenodo.17540639