In South Asia, a region facing rapid economic growth, immense population pressure, and high climate vulnerability, the circular economy (CE) has become a critical imperative for sustainable development. This study provides a comparative overview of the CE landscape across eight South Asian countries: Afghanistan, Bangladesh, Bhutan, India, Maldives, Nepal, Pakistan, and Sri Lanka. The analysis reveals the CE transition is nascent region-wide, though India has advanced its policy landscape through a comprehensive suite of rules and missions and Pakistan is developing a national policy. The primary focus remains on waste management, evidenced by programs like Bhutan’s ‘Zero Waste by 2030’ vision, the Maldives’ Single-Use Plastic Phase-Out Plan, and Sri Lanka’s Clean Sri Lanka Programme. While Extended Producer Responsibility (EPR) is emerging for plastics and e-waste in India, Bangladesh, Sri Lanka, and Pakistan, a significant “policy-practice gap” persists, undermined by weak enforcement and governance fragmented across priority sectors like plastics, food systems, and textiles. Most major CE initiatives are catalyzed by international development partners, with regional programs playing a key role in funding innovation. Finally, while the informal sector is the backbone of material recovery, ensuring a just transition that improves working conditions and secures livelihoods remains a critical challenge. The absence of a cohesive regional framework limits collaboration. Scaling the circular economy in South Asia requires integrated national strategies, prioritizing a just transition for the informal sector, and establishing a regional platform for policy harmonization to create self-sustaining system through multi-sectoral involvement, including the business sector.

Abstract CLIPPIRs (Cullinan-like, large, inclusion-poor, pure, irregular, resorbed) are the rarest and most exceptional gem-quality diamonds, but their occurrence is reported in few kimberlites. Despite their light carbon isotopic composition indicating a genetic link with subducted slabs, the nature of their growth substrate is poorly constrained. Using olivine geochemistry as a proxy of the composition and depth of entrained mantle wall-rock, we show that CLIPPIRs are predominantly associated with Fe-rich kimberlites sampling vertically extensive, Fe-rich domains at the base of the lithosphere. These domains have light oxygen and heavy iron isotopic signatures, consistent with hydrothermally-altered oceanic crust. The geographic association and Fe-C-O isotopic affinity between CLIPPIR and other sub-lithospheric diamonds with these Fe-rich domains suggests a common origin. Partial retrogression of majorite inclusions is consistent with a model in which subducted CLIPPIR substrate was accreted to the lithosphere by buoyant mantle upwelling, following temporary stalling within the mantle transition zone. Subsequent interaction between early kimberlitic melts and these domains produced megacrysts at the base of the lithosphere. These megacrysts were then sampled along with CLIPPIR and other sub-lithospheric diamonds by ascending kimberlite melts. Beyond providing the largest diamonds, these Fe-rich, isotopically anomalous domains contribute to the isotopic heterogeneity of intraplate magmas globally. Similar content being viewed by others Diamond preservation in the lithospheric mantle recorded by olivine in kimberlites Article Open access 02 November 2023 Cubic Fe-bearing majorite synthesized at 18–25 GPa and 1000 °C: implications for element transport, subducted slab rheology and diamond formation Article Open access 22 September 2023 Primordial neon and the deep mantle origin of kimberlites Article Open access 06 April 2025 Data availability The olivine geochemistry and kimberlite bulk-rock Fe-isotope data generated in this study have been deposited in the Figshare database under the https://doi.org/10.6084/m9.figshare.30801557 References Smith, E. M. et al. Large gem diamonds from metallic liquid in Earth’s deep mantle. Science 354, 1403–1405 (2016). Google Scholar Motsamai, T., Harris, J. W., Stachel, T., Pearson, D. G. & Armstrong, J. Mineral inclusions in diamonds from Karowe Mine, Botswana: super-deep sources for super-sized diamonds? Mineral. Petrol. 112, 169–180 (2018). 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Google Scholar Download references Acknowledgements Samples for this study were sourced from the John J. Gurney Mantle collection housed at the University of Cape Town with additional samples collected by AG with thanks to Petra diamonds and Rio Tinto. GHH acknowledges funding from the DSI-NRF Center of Excellence (CoE) for Integrated Mineral and Energy Resource Analysis (DSI-NRF CIMERA) towards this research is hereby acknowledged. Opinions expressed and conclusions arrived at, are those of the author(s) and are not necessarily to be attributed to the CoE. JL acknowledges funding from the National Natural Science Foundation of China (No. 42425302). Christian Reinke is thanked for help with microprobe analyses at the University of Johannesburg. Emma Bullock is thanked for help with EPMA analyses at Carnegie. Riana Rossouw is thanked for help with laser ablation analyses at the University of Stellenbosch. Discussion with several colleagues including Peng Ni, Graham Pearson, Steve Shirey, Evan Smith, Thomas Stachel, Suzette Timmermann, Mike Walter and Qiwei Zhang substantially improved the contents of this work even though they do not reflect the opinions of these colleagues. Author information Author notes These authors contributed equally: Geoffrey H. Howarth, Andrea Giuliani. Authors and Affiliations Department of Geological Sciences, University of Cape Town, Rondebosch, South Africa Geoffrey H. Howarth & Merrily M. Tau Earth and Planets Laboratory, Carnegie Institution for Science, Washington DC, USA Andrea Giuliani State Key Laboratory of Geological Processes and Mineral Resources, and Frontiers Science Center for Deep-time Digital Earth, China University of Geoscience, Beijing, China Ronghua Cai & Jingao Liu School of Natural Sciences, 12 Wally’s Walk, Macquarie University, Sydney, Australia Ronghua Cai Research School of Earth Sciences, Australian National University, Canberra, Australia Ronghua Cai Authors Geoffrey H. Howarth View author publications Search author on:PubMed Google Scholar Andrea Giuliani View author publications Search author on:PubMed Google Scholar Merrily M. Tau View author publications Search author on:PubMed Google Scholar Ronghua Cai View author publications Search author on:PubMed Google Scholar Jingao Liu View author publications Search author on:PubMed Google Scholar Contributions G.H.H. and A.G. contributed equally to this paper including conceptualization and writing the original and revised drafts. G.H.H., A.G., and M.T. collected EPMA and laser ablation data for olivine. J.L. and R.C. were responsible for Fe isotope data collection. G.H.H. drafted all figures and compiled online datasets. All authors contributed to the writing, editing, and reviewing the manuscript drafts. Corresponding authors Correspondence to Geoffrey H. Howarth or Andrea Giuliani. Ethics declarations Competing interests The authors declare no competing interests. Peer review Peer review information Nature Communications thanks Emma Tomlinson and the other, anonymous, reviewers for their contribution to the peer review of this work. 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Nat Commun (2026). https://doi.org/10.1038/s41467-026-72060-0 Download citation Received: 12 June 2025 Accepted: 08 April 2026 Published: 19 April 2026 DOI: https://doi.org/10.1038/s41467-026-72060-0 Share this article Anyone you share the following link with will be able to read this content:Get shareable link Sorry, a shareable link is not currently available for this article. Copy shareable link to clipboard Provided by the Springer Nature SharedIt content-sharing initiative Subjects Economic geology Petrology

Abstract The bostonite dikes in the studied area of Egypt are one of the most radioactive felsic intrusions found in the South Eastern Desert due to their elevated levels of natural occurring radionuclides and the radiological hazards associated with them. This study presents an integration of geochemical signatures and gamma-ray spectrometry data to quantify the activity concentrations of 238U, 232Th, and 40K found in bostonite samples. Geochemical characterization was performed using ARL X-ray fluorescence, while radioactivity was measured using a calibrated sodium iodide (NaI(Tl)) gamma-ray spectrometer. The geochemical signatures of the investigated bostonite dikes from El Sela-Qash Amir area reveal that the analyzed samples fall in trachyte field, calc-alkaline affinity. They are distinguished by remarkable higher concentrations in large-ion lithophile elements (LILEs) and high field strength elements (HFSEs). Gamma-ray investigations have revealed significant and variable levels (Mean ± standard deviation) of 238U (150 ± 47 Bq kg− 1), 232Th (103 ± 17 Bq kg− 1), and 40K (1379 ± 182 Bq kg− 1) compared to average global crustal values. The statistical results of multivariate analysis (including Pearson’s correlation coefficient, hierarchical cluster analysis, and principal component analysis) indicated that 238U and 40K were the most significant contributors to the variation observed in radiological hazard parameters across the bostonite. Based on the radiological hazard parameters calculated, samples of bostonite near their highest acceptable limits and ELCR calculations indicate that long-term exposure may have a detrimental health impact. These results demonstrate that bostonite disturbances have significant radiological importance and warrant future monitoring and regulation due to the health effects of the bostonite rocks at studied area. 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Hanfi Department of Physics, Dogus University, Dudullu-Ümraniye, 34775, Istanbul, Türkiye Mohamed Y. Hanfi Authors Ahmed E. Abdel Gawad View author publications Search author on:PubMed Google Scholar Reham M. Abd El Rahman View author publications Search author on:PubMed Google Scholar Mohamed Y. Hanfi View author publications Search author on:PubMed Google Scholar Contributions A.E.A.G.: Conceptualization, data curation, formal analysis, investigation, methodology, software, validation, visualization, writing-original draft, writing-review and editing. R.M.A.E.R.: Conceptualization, data curation, formal analysis, investigation, methodology. M.Y.H.: Conceptualization, data curation, formal analysis, investigation, methodology, software, visualization, writing-original draft, writing-review and editing. Corresponding author Correspondence to Ahmed E. Abdel Gawad. Ethics declarations Competing interests The authors declare no competing interests. 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To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. Reprints and permissions About this article Cite this article Gawad, A.E.A., El Rahman, R.M.A. & Hanfi, M.Y. Radiological risk assessment and geochemical signatures of calc-alkaline bostonite dikes. Sci Rep (2026). https://doi.org/10.1038/s41598-026-45855-w Download citation Received: 04 May 2025 Accepted: 23 March 2026 Published: 19 April 2026 DOI: https://doi.org/10.1038/s41598-026-45855-w Share this article Anyone you share the following link with will be able to read this content:Get shareable link Sorry, a shareable link is not currently available for this article. Copy shareable link to clipboard Provided by the Springer Nature SharedIt content-sharing initiative Keywords Bostonite Radiological hazards Geochemical signatures Gamma-ray spectrometry Multivariate statistical analysis Subjects Environmental sciences Natural hazards

Abstract Rice husk ash (RHA), a silica-rich by-product from rice husk combustion, serves as an eco-friendly partial cement replacement, contributing to reduced greenhouse gas emissions and sustainable construction practices. This study develops a practical predictive optimization framework for Rice Husk Ash Concrete (RHAC) targeting compressive strength (CS) alongside CO2 and SO2 emission reductions. Two ensemble learning strategies, voting and stacking, integrate Histogram Gradient Boosting (HGB) and Light Gradient Boosting (LGB) models, complemented by a Dempster–Shafer-based ensemble for enhanced prediction accuracy. Multi-objective optimization is performed using the Artificial Protozoa Optimizer (APO) and Electric Eel Foraging Optimization (EEFO) to explore trade-offs between mechanical and environmental performance. The Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) supports final decision-making, identifying balanced RHAC mixture designs. The proposed approach delivers high predictive accuracy and effective optimization, offering a robust pathway toward greener and more sustainable concrete production. Data availability Dataset sources has been provided in the Appendix A. Abbreviations RHA: Rice Husk Ash USDA: United States Department of Agriculture SCM: supplementary cementing material RHAC: Rice Husk Ash Concrete HGB: Histogram Gradient Boosting APO: Artificial Protozoa Optimizer HGEF: HGB+EEFO HGAP: HGB + APO HGLG: HGB + LGB DS: Damesper-Shafer \(\:{ST}_{HGLG}^{AP}\) : Stacking of APO + HGB+LGB \(\:{VO}_{HGLG}^{EF}\) : Voting of APO + HGB+LGB \(\:{DS}_{HGLG}^{EF}\) : Damesper-shafer of APO + HGB+LGB VOHGLG : Voting of HGB + LGB DSHGLG : Damesper-Shafer of HGB + LGB SI: Scatter Index U95: 95% uncertainty CO2 : Carbon Dioxide C: cement GWP: Global Warming Potential OPC: Ordinary Portland Cement CS: Compressive Strength OPC: Ordinary Portland Cement EEFO: Electric Eel Foraging Optimization APO: Artificial Protozoa Optimizer LGB: Light Gradient Boosting EEFO: Electric Eel Foraging Optimization LGEF: LGB+EEFO LGAP: LGB + APO ST: Stacking VO: Voting \(\:{ST}_{HGLG}^{EF}\) : Stacking of EEFO + HGB+LGB \(\:{VO}_{HGLG}^{AP}\) : Voting of EEFO + HGB+LGB \(\:{DS}_{HGLG}^{AP}\) : DS of EEFO + HGB+LGB STHGLG : Stacking of HGB + LGB R2 : Correlation of determination RMSE: Root Mean Square Error ML: Machine Learning SO2 : Sulfur Dioxide w/c: water-to-cement ratio RHA/C: ratio of RHA to cement AP: Acidification Potential References Nadgouda, P. 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Ben Seghier, 9Investigation of performance metrics in regression analysis and machine learning-based prediction models. in 8th European Congress on Computational Methods in Applied Sciences and Engineering (ECCOMAS Congress 2022) (2022). Download references Author information Authors and Affiliations Department of Civil Engineering, Department of Building Materials, Faculty of Engineering and Architecture, Kırşehir Ahi Evran University, Kırşehir, Turkey Hakan Çaglar Authors Hakan Çaglar View author publications Search author on:PubMed Google Scholar Contributions Hakan Çaglar conceived and designed the study, developed the methodological framework, and supervised the overall research. He carried out data analysis, implemented the machine learning models and multi-objective optimization techniques, and interpreted the results. He also prepared the original draft of the manuscript and performed critical revisions. The author read and approved the final version of the manuscript. Corresponding author Correspondence to Hakan Çaglar. Ethics declarations Competing interests The authors declare no competing interests. Additional information Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. Supplementary Information Below is the link to the electronic supplementary material. Supplementary Material 1 (download DOCX ) Supplementary Material 2 (download XLSX ) Rights and permissions Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. Reprints and permissions About this article Cite this article Çaglar, H. Sustainable mixture design of rice husk ash cement based concrete: performance optimization through data driven modeling and multi objective analysis. Sci Rep (2026). https://doi.org/10.1038/s41598-026-47921-9 Download citation Received: 29 December 2025 Accepted: 03 April 2026 Published: 19 April 2026 DOI: https://doi.org/10.1038/s41598-026-47921-9 Share this article Anyone you share the following link with will be able to read this content:Get shareable link Sorry, a shareable link is not currently available for this article. Copy shareable link to clipboard Provided by the Springer Nature SharedIt content-sharing initiative Keywords Rice Husk Ash Cement-Based Materials Sustainable Concrete Supplementary Cementitious Materials Mixture Design Compressive Strength Environmental Performance Subjects Engineering Environmental sciences Mathematics and computing

Abstract Unravelling a reliable timing of past earthquakes through luminescence dating of fault gouge depends on sufficient frictional heat during a co-seismic event to fully reset the luminescence signal. Laboratory fault-gouge production using a rotary shear apparatus has attracted interest as a method for probing the degree of signal resetting in quartz during friction experiments. However, natural fault gouges are complex, exhibiting a mixture of minerals that are specific to the host rocks. Here, we employed a host rock sample from the Alborz Mountains (Iran) and subjected it to a friction experiment without any chemical treatment, after being reset and irradiated with a known gamma dose. We performed a medium-slip velocity friction experiment with a slip velocity of 0.05 m/s and a normal stress of 12 MPa, while the temperature evolution of the gouge zone was recorded using an infrared camera. The thermographic images show a transient temperature of approximately 296 °C, with the luminescence signal resetting at a small, extremely localised slip patch, confirming the challenges involved in identifying the best spot for signal resetting. However, we identified a high-temperature signal enhancement in the thermoluminescence (TL) curves that might serve as a marker for fault-gouge formation. Data availability Raw and partially processed data are available at Zenodo: https://doi.org/10.5281/zenodo.16904960 References McCalpin, J. (Ed.): Paleoseismology, 2nd ed., Academic Press, Burlington, MA, 613 pp. (2009). Tagami, T. Thermochronological investigation of fault zones. Tectonophysics 538–540, 67–85. https://doi.org/10.1016/j.tecto.2012.01.032 (2012). Google Scholar Vrolijk, P., Pevear, D., Covey, M. & LaRiviere, A. Fault gouge dating: History and evolution. Clay Miner. 53, 305–324. https://doi.org/10.1180/clm.2018.22 (2018). 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Google Scholar Download references Acknowledgements We thank the Research Institute for Earth Sciences and the Geological Survey of Iran (GSI) for their support in accessing sites and shipping the samples. We are grateful to Daniel Leyrer, Christian Naber, and Dr Stefan Heise from the irradiation facility at the Karlsruhe Institute of Technology (KIT) for their invaluable support. We thank Dr Hans-Peter Meyer and Dr Alexander Varychev from the Institute of Earth Sciences at Heidelberg University for performing the REM analyses. The Research Institute for Earth Sciences of the Geological Survey of Iran handled the permissions that were required to collect the rock samples for this study. We thank the two anonymous reviewers for their constructive comments on the earlier version of this manuscript. Funding Open Access funding enabled and organized by Projekt DEAL. MH received funding from the Alexander von Humboldt Foundation (#FRA 1221685 HFST-P) and the German Science Foundation (DFG grant #507272784), and the research stay at Utrecht University and facility access to the rotary shear apparatus were supported by the EPOS-NL (Earth Plate Observing System-Netherlands). SK was funded through the DFG Heisenberg programme (#505822867). AN acknowledges support by the NAM (Netherlands Aardgas Maatschappij) for the acquisition of the IR system, and C–C H was supported by NWO (Dutch Research Council) DEEP-NL grant 2018.040. Author information Authors and Affiliations Institute of Earth and Environmental Sciences, University of Freiburg, Albertstr. 23B, 79104, Freiburg, Germany Maryam Heydari & Frank Preusser Institute of Geography, Heidelberg University, Im Neuenheimer Feld 348, 69120, Heidelberg, Germany Maryam Heydari & Sebastian Kreutzer LIAG Institute for Applied Geophysics, Stilleweg 2, 30655, Hanover, Germany Maryam Heydari, Sebastian Kreutzer & Sumiko Tsukamoto HPT Laboratory, Department of Earth Sciences, Utrecht University, Utrecht, The Netherlands Chien-Cheng Hung & André Niemeijer Research Institute for Earth Sciences, Geological Survey of Iran, Azadi Square, Meraj Avenue, P.O. Box 131851494, Tehran, Iran Mohammad R. Ghassemi Institute for Geology, University of Innsbruck, Innsbruck, Austria Loïc Martin Department of Geosciences, University of Tübingen, Schnarrenbergstr. 94-96, 72076, Tübingen, Germany Sumiko Tsukamoto Authors Maryam Heydari View author publications Search author on:PubMed Google Scholar Sebastian Kreutzer View author publications Search author on:PubMed Google Scholar Chien-Cheng Hung View author publications Search author on:PubMed Google Scholar Mohammad R. Ghassemi View author publications Search author on:PubMed Google Scholar Loïc Martin View author publications Search author on:PubMed Google Scholar Sumiko Tsukamoto View author publications Search author on:PubMed Google Scholar Frank Preusser View author publications Search author on:PubMed Google Scholar André Niemeijer View author publications Search author on:PubMed Google Scholar Contributions M.H. conceived the project and its funding, prepared the first manuscript, and conducted and organised laboratory experiments in Utrecht and Freiburg. S.K. carried out the TL and spectrometry measurements at Heidelberg University and, in part, the related data analysis. C-C.H. performed the friction experiments at Utrecht. M.R.G. organised the field work and supported the geological analysis in the field. L.M. performed the simulations required for the gamma-irradiation. S.T. advised on the fault gouge luminescence measurements. F.P. was the host of the Humboldt project and supported the research. A.N. organised and performed the friction experiments, produced friction simulation data, and acquired the funding for these experiments. All authors reviewed and approved the final manuscript. Corresponding author Correspondence to Maryam Heydari. Ethics declarations Competing interests The authors declare no competing interests. Additional information Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. Rights and permissions Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. Reprints and permissions About this article Cite this article Heydari, M., Kreutzer, S., Hung, CC. et al. Unveiling earthquakes: thermoluminescence signal resetting of a natural polymineral sample in laboratory-produced fault gouge. Sci Rep (2026). https://doi.org/10.1038/s41598-026-47125-1 Download citation Received: 20 August 2025 Accepted: 30 March 2026 Published: 19 April 2026 DOI: https://doi.org/10.1038/s41598-026-47125-1 Share this article Anyone you share the following link with will be able to read this content:Get shareable link Sorry, a shareable link is not currently available for this article. Copy shareable link to clipboard Provided by the Springer Nature SharedIt content-sharing initiative Subjects Natural hazards Solid Earth sciences

Abstract CLIPPIRs (Cullinan-like, large, inclusion-poor, pure, irregular, resorbed) are the rarest and most exceptional gem-quality diamonds, but their occurrence is reported in few kimberlites. Despite their light carbon isotopic composition indicating a genetic link with subducted slabs, the nature of their growth substrate is poorly constrained. Using olivine geochemistry as a proxy of the composition and depth of entrained mantle wall-rock, we show that CLIPPIRs are predominantly associated with Fe-rich kimberlites sampling vertically extensive, Fe-rich domains at the base of the lithosphere. These domains have light oxygen and heavy iron isotopic signatures, consistent with hydrothermally-altered oceanic crust. The geographic association and Fe-C-O isotopic affinity between CLIPPIR and other sub-lithospheric diamonds with these Fe-rich domains suggests a common origin. Partial retrogression of majorite inclusions is consistent with a model in which subducted CLIPPIR substrate was accreted to the lithosphere by buoyant mantle upwelling, following temporary stalling within the mantle transition zone. Subsequent interaction between early kimberlitic melts and these domains produced megacrysts at the base of the lithosphere. These megacrysts were then sampled along with CLIPPIR and other sub-lithospheric diamonds by ascending kimberlite melts. Beyond providing the largest diamonds, these Fe-rich, isotopically anomalous domains contribute to the isotopic heterogeneity of intraplate magmas globally.

Abstract Self-assembled molecule (SAM) layers have significantly enhanced the efficiency of inverted perovskite solar cells (PSCs). However, SAM aggregation leads to non-uniform interfacial contact, limiting further improvements in efficiency and stability. Here we employ perfluoro-2-propoxypropanoic acid (PFA) to construct a molecular confinement structure on the surface of the NiOx substrate. This confinement structure enables uniform embedding of SAMs within the PFA sub-monolayer and prevents their vertical stacking. Together, PFA and SAM form a complete interlayer that enhances the interface contact and reduces defects between NiOx and perovskite. Moreover, PFA molecules in the confinement structure interact with the buried perovskite interface via hydrogen bonding and dipolar interaction, further stabilizing the structure. These enhancements enable PSCs to achieve an efficiency of 26.84% (certified value of 26.79%) with a high fill factor of 86.61%. And the device exhibits excellent operational stability, retaining 94.6% of its initial efficiency after 800 hours of 1-sun maximum power point tracking under the ISOS-L-1 protocol.

When you’re thinking about urban infrastructure, the first things that come to mind are probably related to transportation, utilities, communications and public services. Shade is probably not on that list. But if you’re a mile closer to the sun, as Denver is, it should be, according to an expert in environmental health and urban greenness. “As the climate changes, many cities have increased their focus on studying sun exposure,” said Sara Tabatabaie, an assistant teaching professor of environmental design. “But they’re doing so mainly from a heat mitigation standpoint, and not necessarily for skin cancer prevention.” Earlier this year, Tabatabaie received a third grant to continue studying how Denver, and other cities, can engage in sun safety planning and shade design to make the outdoors a less hazardous place for your skin. Worldwide, skin cancer is the most common form of cancer; in Colorado, it is a rising problem, per the National Cancer Institute. Creating novel guidelines It’s such a novel consideration for designers and public health officials that Tabatabaie’s work really had to start at the beginning. In the early phases of this project—a partnership between the Colorado Department of Public Health and Environment and the Community Engagement, Design and Research Center—she developed an intensive methodology to assess ultraviolet exposure in different urban environments, or typologies. From there, she proposed design guidelines—customized for different public space typologies—to help neighborhoods hit appropriate sun safety thresholds. “This work incorporates lived experiences of shade and place into real design guidelines,” she said. To do so effectively, she and student researchers from CEDaR completed extensive surveys—audits, observation, environmental modeling and parametric simulation—to establish design guidelines that could improve UV safety for each typology as the sun moves through the sky during the day. Sara Tabatabaie’s research looks at sun mitigation from the standpoint of UV protection. Other research has mostly focused on heat prevention. Photo by Nathan Thompson. Project visualizations illustrate the placement of shade structures related to play areas. This one shows shade at Scott Carpenter Park, in Boulder, in the afternoon. The current phase of the project is translating her evidence-based findings into actionable strategies that can guide policy and transform neighborhoods for sun safety. Tabatabaie hopes that, through this work, CDPHE can craft stronger urban forestry initiatives, improve streetscape requirements and invest in neighborhoods that lack sun protection. “In this next phase, I’ll be investigating the institutional and political pathways for shade interventions, so we understand how to integrate these findings into urban policies, regulatory codes and planning frameworks,” she said. She also plans to perform a cost-benefit analysis of shade. “We want to be able to share the cost of implementing shade against the health benefits that shade offers to residents,” she said. “We know cost will be an important consideration for helping people understand the value of introducing shade into these typologies.” Jota Samper In the first phase of the project, the team—Tabatabaie; Jota Samper, associate professor and co-director of CEDaR; and a team of environmental design students—surveyed six different neighborhoods throughout the city to assess shade and sun risk. The orientation of streets, walkability and sidewalk types were shown to directly affect the sun risk index; the survey also revealed neighborhoods with a higher percentage of children provided limited shade—problematic, as children are more susceptible to sun damage than adults. “What I found fascinating about Sara is that she took tools that are used in other fields”—like Rhino, a versatile 3D modeling tool, and related applications like Grasshopper and Ladybug—“and applied them to her interest in research,” Samper said. “It was amazing to see how she implemented them not just to measure sun exposure, but to show how different modalities of design could have different impacts, and help us visualize and understand that in a more complex way.” The work may seem simple on its face, but there are a number of quirks that become apparent the more you look at shade. Cover from trees, for instance, is variable on windy days and mostly disappears in the winter. Meanwhile, surfaces designed to reflect sunlight, and protect from heat, may reflect those UV rays back at people. “Until now, shade thresholds have not been consistently defined across all typologies, which has made it more difficult to design sun-safe places,” Tabatabaie said. “Community engagement, and using people’s lived experience, is so important in the design process. Because if people don’t believe in the design, they won’t use it.” Sara Tabatabaie, assistant teaching professor, environmental design All this is happening against the backdrop of cities embracing the outdoors and encouraging residents to spend time outside by investing in parks, multiuse trails and micromobility options. But based on average UV levels in Denver, more than 20 minutes of direct sun exposure is not recommended, especially for fair-skinned people. Balancing more time outdoors with more awareness of sun risk is something Tabatabaie takes seriously in her work. “Community engagement, and using people’s lived experience, is so important in the design process. Because if people don’t believe in the design, they won’t use it,” she said. “We can’t just design something that looks great. We have to observe how people behave and interact with a design to ensure we’re creating something people want to use.” Student research impact That’s a lesson she imparted to the students working alongside her on the project. Gabby Rodriguez, a senior majoring in landscape architecture, studied urban trail systems to help guide recommendations for that typology. “Looking at the climate we live in today demonstrates that smart landscape architecture projects are more needed than ever—especially at a time when everything is changing so rapidly,” said Rodriguez, who hopes to do more public-oriented projects after graduating this spring. “But the challenging part is definitely putting the scientific processes and methodologies into terms that the general public can understand, so you can convey that importance to people.” The work is especially important to Rodriguez, who—like many native Coloradans—never turns down an opportunity to be outdoors. “It’s exciting to see a project like this come to the surface,” she said. “I loved the opportunity to work with Sara, who is one of the most intelligent people I’ve known and is focused on cultivating a good space to bring design solutions for important problems to light.” Tabatabaie’s gift for encouraging her students to become passionate about these issues speaks to her teaching ability, Samper said. “The rigor Sara brings to her research really rubs off on her students,” he said. “The students understood the stakes were high, that this was a real client with a serious issue, and that their research was really going to impact policy in Colorado. That elevated the whole output of the students, which was really wonderful.” Joe Arney covers research and general news for the college.