Some argue that complementing climate change mitigation measures with solar radiation management (SRM) might prove a last resort to limit global warming to 1.5 °C. To make a socially responsible decision on whether to use SRM, it is important to consider also public opinion, across the globe and particularly in the Global South, which would face the greatest risks from both global warming and SRM. However, most research on public opinion about SRM stems from the Global North. We report findings from the first large-scale, cross-cultural study on the public opinion about SRM among the general public (N = 2,248) and students (N = 4,583) in 20 countries covering all inhabited continents, including five countries from the Global South and five ‘non-WEIRD’ (i.e. not Western, Educated, Industrialised, Rich, and Democratic) countries from the Global North. As public awareness of SRM is usually low, we provided participants with information on SRM, including key arguments in favour of and against SRM that appear in the scientific debate. On average, acceptability of SRM was significantly higher in the Global South than in the ‘non-WEIRD’ Global North, while acceptability in the ‘WEIRD’ Global North was in between. However, we found substantial variation within these clusters, especially in the ‘non-WEIRD’ Global North, suggesting that countries do not form homogenous clusters and should thus be considered individually. Moreover, the average participants’ views, while generally neither strong nor polarised, differed from some expert views in important ways, including that participants perceived SRM as only slightly effective in limiting global warming. Still, our data suggests overall a conditional, reluctant acceptance. That is, while on average, people think SRM would have mostly negative consequences, they may still be willing to tolerate it as a potential last resort to fight global warming, particularly if they think SRM has only minor negative (or even positive) impacts on humans and nature.

Throughout the world, climate change, rapid population growth, and urbanisation raise the need for reducing freshwater consumption. One solution are on-site systems that treat wastewater for non-potable reuse near its source of generation, for example within a building. Policies mandating their installation can effectively increase installation rates and have been implemented in several cities. Yet, such policies have the potential to impair distributive fairness in society and therefore also policy acceptance, because usually they cover only part of the population, which then has to carry most costs and risks. On the example of Bengaluru, India, where such a policy exists, this online study (N = 350) analysed whether policy acceptance can be explained by the perceived policy outcome for different groups of society (i.e. the distribution of the policy's costs, risks, and benefits among these groups), and whether this relation is mediated by perceived fairness. We further investigated whether these relations differed between participants covered and those not covered by the policy, since being personally affected may influence perceptions. Specifically, the outcomes for the following six groups were included: 1) participants themselves, 2) people covered by the policy, 3) people with a low income who are covered by the policy, 4) people vulnerable to water insecurity who are covered by the policy, 5) all inhabitants of Bengaluru taken together, and 6) the environment and future generations. A moderated mediation analysis showed that higher acceptance of the policy was explained by a higher perceived fairness, which, in turn, was explained by a better perceived outcome of the policy for different groups of society. Covered and non-covered participants differed with regard to which groups of society they considered for evaluating fairness. While a better perceived outcome for residents covered by the policy (compared with the outcome for those not covered) explained perceived fairness among all participants, it explained acceptance only among participants not covered by the policy. Further, and only among participants covered by the policy, perceived fairness was additionally explained by better perceived outcomes for the environment and future generations, which also explained higher acceptance among covered participants. It is discussed whether in the specific context, collective considerations may be more relevant than self-centred considerations to the perception of fairness and acceptance of the policy.

Value similarity – the extent to which people think institutions managing risks hold different or similar values to themselves, affects trust in those institutions and as such, plays a critical role in the public acceptability of energy projects and policies. Yet, we do not know what constitutes value similarity. How do people judge the level of similarity between their own values and the values of an institution? What role do different values play in theses judgments? And to what extent can these perceived similarities actually increase trust in institutions? To explore this, we decomposed the construct of value similarity into one's personal values and the perceived values of an institution, and explored if their congruence led to higher ratings of perceived value similarity and trust in institutions. We studied these relationships for three institutions playing important roles in the energy sector in the Netherlands, in current and future energy systems. Overall, response surface analyses (RSA) showed that people see their own values and the values of an institution as more similar and trust the institution more when they both endorse biospheric values more strongly. Further, perceived value similarity and trust in institutions are higher when people perceive institutions to have stronger biospheric values than themselves and when they expect institutions to be less egoistic than themselves. We discuss these findings reflecting on what they suggest regarding the role of shared values in increasing trust in relevant institutions and acceptability of energy risks.

Phasing out fossil fuels is inherent to sustainable energy transitions, but implementing energy policies related to phasing out processes involves risks that may affect their public support. Trust in institutions responsible for handling these risks is crucial for public acceptability, as it serves as a heuristic for risk assessment. In the current study, using the Dutch energy scenario, we examine how trust in institutions relates to public support for phasing out natural gas in the Netherlands. We build from previous research by examining this for the two types of trust most commonly distinguished in the literature, namely competence- and integrity-based trust, and for institutions operating at both national and local levels. Results showed that trust depends on the type of trust people evaluate and on the institution’s level of operation. Locally, institutions are seen as more honest and transparent, while nationally, they’re perceived as more skilled and having more knowledge. Further, integrity-based trust in both local and national institutions better explained public support for phasing out natural gas than competence-based trust. We discuss these results in terms of their implications for energy policy, suggesting policymakers consider trust dynamics and tailor strategies based on trust dimensions and institutional levels to facilitate phasing out processes.

Decentralized water treatment technologies could help in addressing global key water issues. Their successful implementation, however, depends on users' positive valuation and, depending on the technology, 'passive' use (rooted in acceptance), 'engaged' use (rooted in support) or 'active' use (rooted in behaviour change). Although users' valuation of a technology is contingent on its characteristics, positive valuation and use usually also require supporting promotion activities. Here we review the literature on psychological determinants of use as well as change techniques to promote use, and propose a user-focused theory of change to guide promotions. Our review highlights a lack of (conclusive) evidence on both psychological determinants and effective change techniques. We call on environmental and health psychologists to intensify their research on 'passive', 'engaged' and 'active' use of decentralized water treatment technologies and encourage engineers, practitioners and psychologists to intensify collaboration to ensure that technologies, implementation and promotions are optimally integrated.

In dealing with water pollution and freshwater scarcity, on-site treatment and reuse of domestic wastewater has shown to be a promising solution. To increase on-site wastewater treatment and reuse, some cities, among them Bengaluru in India, have mandated the installation and use of the necessary technology in certain building types. However, even with a mandate, a successful and sustainable implementation of the technology, including reliable operation, monitoring, and maintenance, depends on the acceptance (i.e. positive valuation) of the technology and its use by the (prospective) users. Literature on technology acceptance indicates perceived costs, risks, and benefits of the respective technology as key predictors of acceptance. Therefore, the present online study assessed this relationship for on-site systems in Bengaluru. The relation was analysed separately for mandated users of on-site systems (N = 103) and current non-users (i.e. potential prospective users, should the mandate be expanded; N = 232), as the perceptions might differ between the two groups, due to the personal experience with the technology among users. The results show that for mandated users and non-users, acceptance of on-site systems is explained by perceived benefits only, namely a positive image of users, environmental benefits, and, only for non-users, also financial benefits for the city. The findings suggest that interventions aimed at promoting on-site systems should include emphasis on the benefits of on-site systems. Whenever possible, interventions should be tailored to the target group's individual cost, risk, and benefit perception.

Public acceptability of energy production does not only depend on people's opinions of energy projects but also on whether people trust those who are in charge of regulating them. Indeed, research shows that trust in regulating institutions is positively related to public acceptability of energy production, and more generally, to public acceptability hazard-prone activities. Most evidence for this relationship, however, stems from correlational and cross-sectional studies and therefore causal inferences regarding its directionality cannot be made. That is, is not clear whether trust is an antecedent of public acceptability (the causal model of trust) or whether trust is rather a consequence of it (the associationist model of trust). In this study, we aimed to fill this gap by studying longitudinally the association between trust in two relevant regulating institutions associated with energy production in the Netherlands and public acceptability of natural gas extraction. Overall, results provided (partial) support to the causal model of trust –that is, trust in one of studied regulating institutions influenced subsequent acceptability ratings in 2 (out of 5) measurement waves. Further, both trust and public acceptability tended to be stable over time. Results are discussed in relation to the literature on trust in institutions and its effects on the acceptability of hazard-prone activities.

Emotions may play an important role in how citizens respond to public policies, and energy policies in particular. Yet, little insights exist into causes of those emotions. This study investigates ethical concerns as the basis of emotions. We test whether people perceive an unequal distribution of negative outcomes of a local energy project as more unfair than an equal distribution thereof and, in turn, experience stronger negative emotions (hypothesis 1) and whether these effects depend on whether the project has personal consequences or not (i.e. the self-relevance of the project; hypothesis 2). In an experiment with a 2 (equal vs. unequal distribution) by 2 (self-relevant vs. not self-relevant) design (N = 282), we find support for hypothesis 1, but not 2. Furthermore, we find that perceived total amount of harm, an ethical concern about the total amount of negative outcomes bestowed on all people together, is also (marginally significantly) affected by the unequal distribution and relates to the emotions. We argue that justified ethical concerns are at the root of emotions about renewable energy projects and therefore emotions and their underlying ethical concerns should be considered for socially responsible as well as successful energy policy making.

Public resistance to sustainable innovations is oftentimes accompanied by strong negative emotions. Therefore, it is essential to better understand the underlying factors of emotions toward sustainable innovations to facilitate their successful implementation. Based on the Value-Innovation-Congruence model of Emotional responses (VICE model), we argue that positive and negative emotions toward innovations reflect whether innovations are congruent or incongruent with (i.e., support or threaten) people's core values. We tested our reasoning in two experimental studies (N = 114 and N = 246), by asking participants to evaluate innovations whose characteristics were either congruent or incongruent with egoistic values (study 1) or with biospheric values (study 1 and study 2). In line with the VICE model, we found overall that the more an innovation was perceived to have characteristics congruent with these values, and biospheric values in particular, the stronger positive and the weaker negative emotions they experienced toward the innovation, especially the more strongly people endorsed these values. Emotions, in turn, were related with acceptability of innovations. Our findings highlight that emotions toward innovations can have a systematic basis in people's values that can be addressed to ensure responsible decision-making on sustainable innovations.

Policies that mandate the adoption of renewable energy innovations could ensure their widespread adoption. Yet, such policies may not be implemented if they face strong opposition from the public, especially when strong negative emotions are at the core of opposition. In a field experiment (N = 97), we investigated people's emotional responses to two policy options aimed at increasing the adoption of heat pumps in a neighbourhood in the city of Groningen: a campaign promoting the voluntary adoption of heat pumps versus a regulation that mandates the adoption of heat pumps. In line with reactance theory, the policy option mandating the adoption of heat pumps was perceived to threaten people's freedom more and, in turn, caused stronger negative and weaker positive emotions than the policy option promoting voluntary adoption. Yet, emotions towards the policy options were also related to people's values, providing partial support for the Value-Innovation-Congruence model of Emotional responses. Stronger egoistic values were related with stronger negative emotions, particularly towards the policy option mandating adoption, while stronger biospheric values were related with stronger positive emotions, but only towards the policy option promoting voluntary adoption. Emotions, in turn, were related with acceptability of the policy options. Our findings imply that measures aimed at increasing positive emotions and reducing negative emotions towards policies aimed at increasing the adoption of energy innovations could profit from considering people's core values.

Increasing demands on ecosystems, decreasing biodiversity, and climate change are among the most pressing environmental issues of our time. As changing weather conditions are leading to increased vector-borne diseases and heat- and flood-related deaths, it is entering collective consciousness: environmental issues are human health issues. In public health, the field addressing these issues is known as environmental health. This field addresses both the effects people have on their environment as well as the effects of the environment on people. Psychology, as a discipline concerned with explaining, predicting, and changing behavior has much to contribute to these issues because human behavior is key in promoting environmental health. To date, however, an integrative view of environmental health in psychology is lacking, hampering urgently needed progress. In this paper, we review how the environment and human health are intertwined, and that much can be gained through a systemic view of environmental health in psychology. Based on a review of the literature, we suggest that psychologists unite efforts to promote an integrative science and practice of environmental health psychology, and jointly address environmental-health related behavior. The research agenda for this field will include integrating behavior change theory and intervention approaches. Thereby, psychology can potentially make an important contribution to sustained environmental health for generations to come.

Background: Products made from recycled organic materials are an important part of a circular economy, but the question is whether they will be adopted by the public. Such products can elicit strong emotional responses and public resistance. As a case in point, we studied products made from sewage waste, such as recycled toilet paper, which can serve as material alternative to wood and plastic when making household items (e.g., tables). In an experimental study, we investigated the role of values in emotional responses to such wastewater products, and whether emotional responses were influenced by value-tailored messages. We expected that people would experience positive emotions towards products that supported their values, especially when the messages emphasised the benefits of these products for their values (e.g., when the products were presented as good for the environment). We presented participants with one of two messages describing wastewater products as having positive implications for either biospheric values (i.e. positive consequences for the environment) or hedonic values (i.e. positive consequences for personal enjoyment). We predicted that the relationship between values and positive emotions would be stronger when the messages emphasised the positive implications of wastewater products for one's core values. Additionally, we predicted that emotions would be associated with acceptability and intentions to purchase the products.
Results: The more strongly people endorsed biospheric values, the more positive emotions they reported towards wastewater products. As expected, this relationship was stronger when the environmental benefits of products were emphasised. Hedonic values were significantly but weakly associated with more negative and more positive emotions, and this did not depend on the message framing. However, we found that emphasising pleasurable benefits of wastewater products reduced positive emotions in people with weaker hedonic values. Positive and negative emotions were significantly associated with higher and lower acceptability of the products and intentions to purchase the products, respectively.
Conclusions: Our findings have implications for the effective marketing of wastewater products. For people with strong biospheric values, emphasising the positive environmental consequences may promote wastewater products. Such biospheric messages do not seem to make the products less (or more) appealing for people with strong hedonic values, who do not generally have strong emotional responses to these products. We discuss the theoretical implications of our findings and avenues for future research.

Environmental frames are widely used in an effort to increase public support for energy sources in the sustainable energy transition. Research suggests that environmental frames are most effective when they are congruent with people's biospheric values. Yet, this value-congruence account has been mainly tested for promoting behaviors, policies or products that have clear environmental benefits. But what if they do not? For example, what if energy sources are promoted as green but are not seen as such by the public? We extend the value-congruence account by proposing that besides the congruence between the frames and biospheric values, it is important to consider how much the products themselves are congruent with environmental frames and biospheric values. We tested this novel value-frame-product account by evaluating the effectiveness of environmental frames (vs. financial frames) on the acceptability of energy sources that are typically seen as high, moderate, and low in environmental friendliness, and depending on how strongly people endorse biospheric values. Overall, the results supported none of the congruence accounts, suggesting that matching frames (and products) with people's values might be less effective in enhancing acceptability of products than previously thought. Instead, environmental framing increased the acceptability of all energy sources, independent of people's biospheric values and the perceived environmental friendliness of those energy sources. Moreover, highly environmentally friendly energy sources were more acceptable and evaluated more positively, especially among people who strongly endorsed biospheric values. We discuss the theoretical and practical implications of our study.

Unsafe sanitation practices are a major source of environmental pollution and are a leading cause of death in countries of the Global South. One of the most successful campaigns to eradicate open defecation is "Community-Led Total Sanitation" (CLTS). It aims at shifting social norms towards safe sanitation practices. However, the effectiveness of CLTS is heterogeneous. Based on social identity theory, we expect CLTS to be most effective in communities with stronger social identification, because in these communities individuals should rather follow social norms. We conducted a cluster-randomized controlled trial with 3,216 households in 132 communities in Ghana, comparing CLTS to a control arm. Self-reported open defecation rates and social identification were assessed pre-post. Generalized Estimating Equations showed that CLTS achieved lower open defecation rates compared to controls. This effect was significantly stronger for communities with stronger average social identification. The results confirm the assumptions of social identity theory. They imply that pre-existing social identification needs to be considered for planning CLTS, and strengthened beforehand if needed.

Unsafe water consumption is the environmental risk factor in sub-Saharan Africa contributing most to premature death. In urban slums and dispersed rural communities, where access to safe water is especially limited, water kiosks are a relevant safe water source. However, irregular use challenges their operational viability and may cause discontinuation. The present study investigated collective psychological ownership for the kiosk as a potential factor to increase regular kiosk use. Data were collected cross-sectionally in one urban and two rural kiosk sites through interviews in study households (N = 205) and analyzed by path analysis. Involvement in decision-making related to the kiosks explained collective psychological ownership for the kiosks. Collective psychological ownership, in turn, explained self-reported kiosk use through social-cognitive factors. The results emphasize the importance of community involvement in decisions related to kiosk installation and maintenance because it may contribute to regular kiosk use.

Improved hand hygiene efficiently prevents the major killers of children under the age of five years in Ethiopia and globally, namely diarrhoeal and respiratory diseases. Effective handwashing interventions are thus in great demand. Evidence- and theory-based interventions, especially when matched to the target population's needs, are expected to perform better than common practice. To test this hypothesis, we selected two interventions drawing on a baseline questionnaire-study that applied the RANAS (Risk, Attitudes, Norms, Abilities, Self-regulation) approach and focused on the primary caregivers of households in four rural, water-scarce kebeles (smallest administrative units of Ethiopia) in southern Ethiopia (N=462). The two interventions were tested in combination with a standard education intervention in a quasi-experiment, as follows: kebele 1, education intervention, namely an f-diagram exercise, (n=23); kebele 2, education intervention and public-commitment (n=122); kebele 3, education intervention and tippy-tap-promotion (i.e. handwashing-station-promotion; n=150); kebele 4, education intervention, public-commitment and tippy-tap-promotion (n=113). In kebeles 3 and 4, nearly 100% of the households followed the promotion and invested material and time to construct for themselves a tippy-tap. Three months after intervention termination, the tippy-taps were in use with water and soap being present in up to 83% of the households (kebele 4). Pre-post data analysis on self-reported handwashing revealed that the population-tailored interventions, and especially the tippy-tap-promotion, performed better than the standard education intervention. Tendencies in observed behaviour and a recently developed implicit self-measure pointed to similar results. Changing people's hand hygiene is known to be a challenging task, especially in a water-scarce environment. The present project suggests not only to apply theory and evidence to improve handwashing interventions' effectiveness, but also emphasizes the relevance of tailoring interventions to the target population.

Each year, around 2 million children younger than five years die due to acute respiratory infections and diarrhoeal diseases. The two diseases are not only the global leading causes of under-five mortality but also major killers in humanitarian disasters. Handwashing with soap at key times is the best preventive measure against diarrheal diseases and an effective barrier to acute respiratory infections. In developing countries, where the death tolls are highest, regular handwashing is rarely habitual. Accordingly, promotion of handwashing should be a priority in development and emergency programs. There is a need and a demand for effective handwashing interventions but rigorous evaluations of handwashing interventions in development and emergency aid are scarce. Evaluation of handwashing interventions are challenging due to the lack of a valid behaviour measure which is at the same time efficiently collected. Consequently, the effectiveness of regularly applied handwashing interventions is uncertain and evidence-based programming an exception. Behaviour change interventions are assumed to be especially effective when they are theory-based, i.e. when they address and thus modify the social-cognitive determinants of a behaviour and consequently change the behaviour itself. [...]

Background: Diarrheal disease kills around 760,000 infants every year. Many of these deaths could have been prevented by handwashing with soap. However, the whole range of psychological factors encouraging handwashing is not yet identified and handwashing campaigns are often limited to awareness-raising and education. The purpose of this article was to identify the psychological determinants of handwashing in Haiti (study 1) and Ethiopia (study 2).
Methods: Data were collected cross-sectionally by administering face-to-face interviews with the primary caregiver in a participating household (N_Haiti = 811; N_Ethiopia = 463). Hierarchical multiple regression analyses were performed on self-reported handwashing.
Results: In both countries, risk factors—meaning awareness and health knowledge—accounted for only 11%-19% of variance in handwashing and were not consistently associated with handwashing. The inclusion of additional factor-groups, namely attitude, norm, ability, and self-regulation factors, led to significant increases in explained variance (P ≤ .01), accounting for 25%-44% of additionally explained variance. The attitude factor disgust, the norm factor, the ability factors motivational self-efficacy and perceived impediments, and the self-regulation factors coping planning and commitment emerged as especially relevant.
Conclusions: Handwashing campaigns should focus especially on attitudes and norms and not only on risk.

Handwashing interventions are a priority in development and emergency aid programs. Evaluation of these interventions is essential to assess the effectiveness of programs; however, measuring handwashing is quite difficult. Although observations are considered valid, they are time-consuming and cost-ineffective; self-reports are highly efficient but considered invalid because desirable behaviour tends to be over-reported. Socially desirable responding has been claimed to be the main cause of inflated self-reports, but its underlying factors and mechanisms are understudied. The present study investigated socially desirable responding and additional potential explanatory factors for over-reported handwashing to identify indications for measures which mitigate over-reporting. Additionally, a script-based covert recall, an alternative interview question intended to mitigate recall errors and socially desirable responding, was developed and tested. Cross-sectional data collection was conducted in the Borena Zone, Ethiopia, through 2.5-hour observations and 1-hour interviews with the primary caregivers in households. A total sample of N = 554 was surveyed. Data were analysed with correlation and multiple regression analyses and dependent t-tests. Over-reporting of handwashing was associated with factors assumed to be involved in (1) socially desirable responding, (2) encoding and recall of information, and (3) dissonance processes. The latter two factor groups explained over-reported handwashing beyond socially desirable responding. The alternative interview question—script-based covert recall—reduced over-reporting compared to conventional self-reports. Although the difficulties involved in measuring handwashing by self-reports and observations are widely known, the present study is the first to investigate the factors which explain over-reporting of handwashing. This research contributes to the limited evidence base on a highly important subject: how to evaluate handwashing interventions efficiently and accurately.

Handwashing with soap effectively prevents diarrhoea, a leading cause of death in infants. Theory-based interventions are expected to promote handwashing more successfully than standard approaches. The present article investigates the underlying change processes of theory-based handwashing interventions. A nonrandomised field study compared a standard approach to two theory-based interventions that were tailored to the target population, the inhabitants of four villages in southern Ethiopia (N = 408). Data were collected before and after interventions by structured interviews and analysed by mediation analysis. In comparison to the standard approach (i.e., education only), education with public commitment and reminder was slightly more effective in changing social-cognitive factors and handwashing. Education with an infrastructure promotion and reminder was most effective in promoting handwashing through enhancing social-cognitive factors. The results confirm the relevance of testing interventions' underlying change processes.

Aim. In a disaster context, where risk for diarrhoeal disease is elevated, personal hygiene, i.e. handwashing with soap, is especially relevant. However, to date, the promotion of hygiene in an emergency context has not been adequately addressed in the literature. The aim of the present study is to evaluate the effectiveness of hygiene promotions in post-earthquake Haiti.
Subject and Methods. Cross-sectional data was collected by means of structured interviews in camps and neighbourhoods in which three affiliates of a well-known relief organisation had conducted hygiene promotions. Primary caregivers were targeted. A total sample of 811 was obtained. Data was analysed using multiple linear regression and mediation analysis. Results. Analysis revealed six promotional channels with positive associations with handwashing behaviour: hygiene radio spots, radio programs with experts answering listener's questions, material distributions with instructions for use, information from friends or neighbours, hygiene theatres, and community clubs. However, five of the promotional channels were negatively related with handwashing. Respondents who experienced a focus group, stickers, posters and paintings, hygiene songs, special hygiene days and home visits tended to wash their hands less often.
Conclusions. By revealing positive but also negative associations between hygiene promotions and handwashing behaviour, the study underlines the need to apply theory-driven emergency hygiene promotions which are subjected to in-depth evaluation. Only through doing this, is it ensured that effective hygiene promotions are implemented for the most vulnerable people — those affected by a humanitarian disaster.