Building evidence regarding nature-based solutions indicators and their implications for policy – the case of air quality

Exposure to fine particulate matter (PM2.5) has been associated with increased risk of heart disease,1 insulin resistance (IR),2 and diabetes,3 all conditions that are characterized by inflammation.4 Experimental data suggest a high-fat diet2 may exacerbate the health effects of inhaled PM2.5; obese people also appear to be at increased risk.1 In this issue of EHP, investigators tease out some of the complex cellular mechanisms that could explain how PM2.5 may work with a high-fat diet to cause IR.5 Some of the authors previously reported that mice breathing PM2.5 and eating a high-fat diet developed IR, systemic inflammation, and increased abdominal fat, compared with mice eating the same diet but breathing filtered air.2 For the current study, the investigators focused on CCR2, a protein that recruits innate immune cells to insulin-sensitive tissues such as visceral fat and the liver, where it induces the inflammation characteristically seen in animal models of obesity and type 2 diabetes.6 They compared wild-type mice that produce CCR2 with “knockout” (CCR2–/–) mice that don’t. All the mice were fed a high-fat diet and then for 17 weeks were exposed to either filtered air or air containing 117 µg/m3 of PM2.5. Among the key findings, PM2.5 exposure was associated with increased IR and increased levels of liver lipids in the wild-type mice. The elevated liver lipids resulted from a rise in SREBP-1c activity5; this protein helps regulate fatty acid synthesis.7 In contrast, liver lipid levels and SREBP-1c activity in CCR2–/– mice were equivalent whether the mice were exposed to PM2.5 or breathing filtered air.5 IR is also characterized by abnormal insulin signaling through the AKT pathway. Reduced phosphorylation of this enzyme is associated with inflammation.8 The researchers found that phosphorylation of AKT was reduced in wild-type mice exposed to PM2.5 but unchanged in CCR2–/– mice. PM2.5 exposure also was associated with higher levels of inflammatory F4/80 macrophages in visceral fat stores, but only in wild-type mice.5 The important message in all these findings is that PM2.5 recruits inflammatory cells via CCR2-dependent mechanisms. “This mechanism directly ties a known inflammatory mechanism in the pathogenesis of type 2 diabetes to exposure to environmental air pollution,” says study leader Sanjay Rajagopalan, division head for cardiology at the University of Maryland Medical Center. The protein CCR2 is involved in the inflammation that characterizes animal models of obesity and type 2 diabetes. Rajagopalan says the inflammatory damage likely creates a vicious cycle that can also contribute to cardiovascular disease and obesity. “We should look more closely at these kinds of associations in human epidemiological studies,” he says. PM2.5 is generated by vehicle exhaust, burning wood and coal, and industrial processes.9 Annual PM2.5 levels in cities in China, India, and Latin America can average 100–150 µg/m3, comparable to the PM2.5 exposure in this study.2 “It’s long been suspected that the immune system played a major role in ‘carrying’ the toxicity of air pollutants beyond the lung,” says Matthew Campen, an associate professor at the University of New Mexico College of Pharmacy, who was not involved in the study. The results by Rajagopalan’s team strongly support the role of the innate immune system in mediating PM2.5 toxicity in tissues far from the lung. The results, Campen says, also suggest that PM2.5 pollution could worsen cardiometabolic syndromes brought on by an unhealthy diet and lifestyle. “This public health burden may be offset by anti-inflammatory drugs or healthy diets,” he says. Alternatively, Rajagopalan proposes, “A practical solution would be to lower levels of PM2.5.” As Campen wryly points out, “These differing approaches may reflect the backgrounds of an environmental health scientist who understands the challenges entailed in further reductions in air pollution levels, compared with a cardiologist who understands how difficult it is to change human behavior.”

Many national governments have incorporated nature‐based solutions (NbS) in their plans to reduce net greenhouse gas emissions. However, uncertainties persist regarding both feasibility and consequences of major NbS deployment. Using the United Kingdom as a national‐level case study, we examined the potential contribution of three terrestrial NbS: peatland restoration, saltmarsh creation and woodland creation. While there is substantial political and societal interest in these three NbS, they also have strong potential for competition with other land uses, which will be a critical barrier to substantial deployment. We conducted a national mapping exercise to assess the potential area available for woodland creation. We then assessed the combined climate change mitigation potential to 2100 for the three NbS options under a range of ambition levels. In line with the most ambitious targets examined, 2 Mha of land is potentially available for new woodland. However, climate change mitigation benefits of woodland are strongly dependent on management choices. By 2100, scenarios with a greater proportion of broadleaved woodlands outsequester non‐native conifer plantations, which are limited by regular timber harvesting. Peatland restoration offers the greatest mitigation per unit area, whilst the contribution from saltmarsh creation is limited by the small areas involved. Overall, the contribution of these NbS to the United Kingdom’s net zero emissions target is relatively modest. Even with the most ambitious targets considered here, by 2100, the total cumulative mitigation from the three NbS is equivalent to only 3 years' worth of UK emissions at current levels. Policy implications. Major deployment of nature‐based solutions (NbS) is possible in the United Kingdom but reaching ‘net zero’ primarily requires substantial and sustained reductions in fossil fuel use. However, facilitating these NbS at the national scale could offer many additional benefits for people and biodiversity. This demands that policy‐makers commit to a UK‐wide strategic approach that prioritises the ‘nature’ aspect of NbS. In the push to reach ‘net zero’, climate change mitigation should not be used to justify land management practices that threaten biodiversity ambitions.

The paper empirically examines the causal relationship between human development and air pollutants incorporating with energy consumption and electricity consumption within the panel vector of autoregression with a strongly balanced panel data set for 59 countries covering the annual period 1990-2012. The findings validate that there is a negatively causal relationship between human development and three types of pollutants, implying that increasing human development results in lower emissions in developing countries. However, all air pollutants do not cause human development. Additionally, while results reveal that improving human development leads to increased carbon emissions, nitrous oxide emissions and greenhouse gas emissions in Asia, it has a negative causal effect on nitrous emissions and greenhouse gas emissions in Latin America and the Caribbean and Africa. The incorporation of energy consumption and electricity consumption suggests that they are not preconditioned to improve human development but they might cause higher carbon emissions. This paper also explores causal relationships among the variables based on panel Granger causality models. Besides, the policy implications from these results are suggested.

Nature-Based Solutions (NBS) offer multiple and diverse benefits for both nature and society as they could simultaneously address a spectrum of environmental, social, and economic aspects. The need to upscale urban environments via NBS has resulted in an ever-increasing demand for structured methodologies and easy-to-implement urban design tools to facilitate their adaptation in standard urban policies and modern practices. Within this context, an innovative multi-dimensional, indicator-based NBS assessment framework for enabling a first-order site-specific selection of NBS has been developed herein. The proposed two-step simple, yet systematic, methodological framework enables urban planners to rank a set of candidate NBS, considered for a site of interest, on the basis of multi-dimensional measurable criteria, instead of founding their decision on a purely subjective interpretation of the potential NBS benefits in view of past good practices.The first step of the proposed methodology exploits readily available data and expert knowledge to eventually deliver an initial site screening through estimating appropriate indicators that monitor site performance in a set of concerns associated with the following categories: (a) Public Health and Well Being, (b) Urban, (c) Environment, (d) Social, and (e) Economic. In particular, urban planners initially perform a qualitative site assessment to evaluate site performance across a list of concerns, representing critical issues identified within each of the aforementioned categories, that could potentially be mitigated via NBS interventions. Although the severity assessment of a particular concern (e.g. air quality, overweight population) is offered in a descriptive form (i.e. High/Moderate/Low/Not a problem/Not a concern), specific thresholds are recommended for each concern to guide stakeholders’ decisions with regards to the transition from one severity state to the other. The second step involves assessing the capacity for each of the NBS identified for the site of interest to mitigate the most pressing site-specific concerns. This NBS impact assessment, likewise the site screening, is performed in a qualitative manner. Hence, based on available literature, past experience and expert opinion, urban planners specify whether a specific NBS could have a Direct/Indirect/No mitigating impact on a particular site concern.Following the input phase, the information related to the severity of the concerns (step 1) is convolved with the ability of an NBS to impact them (step 2) to produce a ranked list of the site-specific candidate NBS on the basis of their efficiency to address the most pressing site concerns. To facilitate this, a score is assigned to each of the qualitative descriptions in both steps. Through multiplying the two step scores per concern and then summing them, a total score per NBS is computed reflecting the overall NBS site-specific score. Supplementary factors could be accommodated by the proposed framework, to account for other aspects that are likely to affect NBS selection, e.g. budget or other constraints.The proposed innovative methodology is also offered in the form of an online application, to serve as a decision-assisting tool for undertaking a first-order NBS selection and consequently prioritising further investigation and detailed modelling to appropriate interventions prior to their implementation.

(Barely) living in smog: China and air pollution

PurposeWomen entrepreneurs face several challenges in creating and running ventures, especially in emerging and developing countries. In this sense, by aiming to generate inputs capable of helping overcome them, this study aims to categorize the policy, managerial and practical implications of articles whose empirical research was in one or more of the 155 emerging and developing countries. Further, although scholars have addressed female entrepreneurship in developed economies, there is scant literature in the context explored here. This article provides suggestions for new studies, helping academics fill gaps in the literature.Design/methodology/approachThis article adopts a systematic literature review approach, performing content analysis and bibliometric description for the sample. The study comprises 77 articles selected from the Scopus and Web of Science databases.FindingsResearch concentrates on Asian countries, with lower incidences in Latin America and Africa. The policy implications focus mainly on the executive rather than legislative spheres. The practical implications focus mainly on entrepreneurial development agencies and women entrepreneurs. Among the suggestions for novel studies, those focusing on methodological choices and female enterprises stand out.Practical implicationsThis paper maps and categorizes the policy, managerial and practical implications, helping to raise governments’, policymakers’ and practitioners’ awareness of the preferred strategies to overcome the challenges of female entrepreneurship.Originality/valueThis paper emphasizes reflections of mutual interest to researchers, policymakers and practitioners, filling gaps in studies that prioritize an academic audience. Regarding the academic audience, this paper contributes to innovatively categorizing suggestions for future research and building an extensive research agenda capable of guiding research in this area.

Purpose: The aim of this paper is to explore the potential of nature-based solutions (NBS) in Sudan’s post-war reconstruction, with a focus on how these solutions can foster long-term sustainability, resilience, and environmental recovery. Design/Methodology/Approach: A comprehensive analysis of global best practices, Sudan’s ecological potential, and relevant institutional frameworks for implementing NBS was conducted. Case studies and policy reviews were employed to examine the effectiveness of NBS in addressing environmental challenges and supporting the recovery process. Findings: NBS, including ecosystem restoration, sustainable agriculture, climate-adaptive infrastructure, and green urban planning, proves effective in enhancing climate resilience, restoring livelihoods, reducing disaster risks, and promoting inclusive, low-carbon development. However, challenges such as limited funding, weak governance, and gaps in technical expertise remain. Originality/Value: A unique perspective is offered regarding the integration of NBS into Sudan’s reconstruction process, highlighting policy recommendations and implementation strategies. The role of NBS in promoting environmental sustainability and socio-economic stability in post-conflict contexts is emphasised, addressing a gap in the existing literature on Sudan’s recovery. Research Limitations/Implications: Limitations include the availability of data on Sudan’s specific ecological conditions post-conflict, as well as potential gaps in local technical expertise and institutional capacity. Additionally, the research relies on global case studies; these may not always be directly applicable to Sudan’s unique context. Practical Implications: Practical guidance is provided for policy-makers, development agencies, and stakeholders involved in Sudan’s reconstruction. Strategic investment in NBS can enable Sudan to transition towards a low-emission economy, ensuring food security, water management, and socio-economic stability while tackling urgent environmental challenges. Keywords: Ecosystem Restoration, Climate Resilience, Sustainable Land Management, Biodiversity Conservation, Green Infrastructure, Community-led Adaptation. Citation: Shazali, H.S. and Adam, Y.O. (2025): Nature-Based Solutions for Sudan’s Reconstruction: A Roadmap to Sustainability and Resilience. International Journal of Sudan Research (IJSR), Vol 12, No. 2, pp. 103-129.

Impacts of nature-based solutions on the urban atmospheric environment: a case study for Eindhoven, The Netherlands

The objectives of the study were to: consider the potential health impacts in Australia and the region arising from changes in air quality occurring as a result of climate change, identify vulnerable groups and potential adaptation measures and discuss the implications for policy. The authors provide an overview of international and national information on the potential health impacts of air pollutants that would most likely be affected by climate change and a discussion of the policy implications. Climate change is likely to have an impact on levels of ozone and possibly particulates, both of which are associated with increased mortality and a range of respiratory and cardiovascular health effects. One of the implications is therefore a possible increase in adverse health effects due to air pollutants. Regional health impact assessments of climate change should address the issue of air quality, consider current coping capacity, and determine the need for adaptation, particularly for vulnerable groups. Implications for policy include the need for improved modeling and forecasting of air pollutant levels, increased efforts to reduce emissions of air pollutants, continued monitoring of air pollutant levels, and monitoring of the incidence of health effects associated with air pollutants in all countries in the region.

Nature‐based Solutions to tackle climate change and restore biodiversity

Air pollution and environmental injustice: Are the socially deprived exposed to more PM2.5 pollution in Hong Kong?

Introduction Nature-based solutions (NbS) involve working with and enhancing nature to address social challenges, aiming to protect, manage and restore natural ecosystems. While recognition of their benefits and cost-effectiveness is improving, there remain challenges to their adoption. Since they are often multi-stakeholder problems and aim to achieve multiple objectives, Multiple Criteria Decision Analysis (MCDA) is a good methodology to assist with their planning and implementation. In addition, software tools that support the MCDA process while evaluating NbS help manage varying stakeholder preferences and facilitate collaboration between them. They also make complex information about NbS problems easier to visualise, express and interpret. Current analyses of NbS either do not focus on MCDA or when they do, they do not examine how software can support the implementation of MCDA in evaluating NbS. Methods This study thus conducted a systematic literature review via Web of Science and Google Scholar to analyse a sample of software that assess NbS using methods that support any part of the MCDA process. We analysed the technical aspects of the software, their scope of analysis and their capability to support complex decision-making for NbS selection, implementation and management. Results and discussion We found that the software assess a wide variety of scopes and often include a spatial GIS component too. They cater to different users, among which are public officials, private-sector businesses and consultants. They mainly assist with the planning and design of NbS, rather than their management. The software assess many different co-benefits of NbS—the most common ones being hydrology, carbon uptake, air quality and socio-economic factors. By suggesting NbS alternatives and describing their performance, they also support decisions by making NbS benefits more understandable and streamlined to decision-makers. Most of the software only allow the assessment of one alternative at a time, rather than supporting the comparison of multiple NbS. Software developers should justify and align their weighting and aggregation methods in documentation and should broaden the scope of their software's analysis in the future to include biodiversity, non-urban NbS and enhancement of stakeholder engagement and cooperation during the whole MCDA process, from problem formulation to provision of a decision recommendation.

In this paper, we reflect on the implications for science, policy and practice of the recently introduced concept of Nature-Based Solutions (NBS), with a focus on the European context. First, we analyse NBS in relation to similar concepts, and reflect on its relationship to sustainability as an overarching framework. From this, we derive a set of questions to be addressed and propose a general framework for how these might be addressed in NBS projects by funders, researchers, policy-makers and practitioners. We conclude that: To realise their full potential, NBS must be developed by including the experience of all relevant stakeholders such that 'solutions' contribute to achieving all dimensions of sustainability. As NBS are developed, we must also moderate the expectations placed on them since the precedent provided by other initiatives whose aim was to manage nature sustainably demonstrates that we should not expect NBS to be cheap and easy, at least not in the short-term.

Since almost half of the world’s population lives in cities and another third in settlements with similar characteristics, the current and future impacts of climate change in cities is of greatest importance. The characteristics of urban environments (reduced long-wave emissions towards the sky due to the blockage effect of the surrounding buildings, construction materials, anthropogenic heat production, lack of green and blue infrastructure) further increase ambient temperatures and cause urban heat islands. Nature-based solutions (NbS) have widely been investigated as a remedy to this challenge, which is quickly worsening due to the combined effects of climate change and the rapid densification of urban settlements. NbS cover a wide scope of measures such as planting roadside trees, greening facades or roofs, re-naturalizing rivers or unsealing of parking spaces to allow rainwater to penetrate and enable evapotranspiration. Yet, the widespread implementation of NbS often meets political, social, legal, financial or spatial barriers. In the presented study we combine interdisciplinary expertise from natural to social and economic sciences and a wide range of methods to evaluate and illustrate, exemplarily for the city of Vienna, how urban areas can implement NbS and overcome the aforementioned barriers. Therefore, (1) a list of possible NbS is compiled; (2), their performance is quantified through numerical micro-climate simulations, (3) their impact and potential trade-offs applying a socio-spatial analysis and survey, (4) individual preferences and willingness to pay are analyzed for a representative sample of 2,181 Viennese residents using a choice experiment, and finally, (5) a consolidated list of NbS is validated within policy workshops.Using this approach we find that substantially transforming an existing quarter by implementing green and blue infrastructure, as well as technical solutions (e.g. sun blinds) may reduce the ambient air temperature by up to 2°C and the mean radiant temperature on some surfaces by up to 45°C, with natural measures being more effective than technical ones. Implementing these measures within the whole city of Vienna may yield a similar temperature effect. The socio-spatial vulnerability assessment identifies few areas where a strong overrepresentation of vulnerable age groups, low-income residents and housing vulnerabilities coincide.  In the city of Vienna, green gentrification owing to rising housing prices for already vulnerable groups thus seems to be very limited, especially as long-standing social housing policies and a rather strict regulation of the private housing markets lead to comparatively stable rent levels. The choice experiment shows a substantial willingness to pay for NbS, suggesting that Viennese citizens would financially support the implementation and maintenance of extensive greening measures. However, the politicians fear the conflicts with the citizens and other political parties as well as stakeholders. Stakeholders from the city authorities map potential physical and legal barriers for local implementation, such as building codes, administrative procedures for permits and inspections, or conflicts over scarce public space.

Impact of the emergency response to COVID-19 on air quality and its policy implications: Evidence from 290 cities in China