Mental health is central to global health and sustainable development. It is shaped both by individual experiences and by access to services, and by broader societal and environmental factors. Laws, policies, governance systems and institutions influence how environmental hazards, damage, services and resources are distributed, affecting people’s livelihoods, safety, opportunities and quality of life¹.

Children and adolescents are particularly vulnerable because exposures to environmental hazards can coincide with sensitive periods of development. Early exposure to mercury, lead and persistent organic pollutants can impair cognitive and behavioural development and increase the risk of mental-health conditions later in life.

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For adults and older people, exposure to heavy metals, air pollution, contaminated water and poor-quality environments can lower their sense of well-being and worsen depression and anxiety. For individuals who rely on natural resources and their communities, depletion of the animal and plant species they depend on and disruptions to traditional ways of life and livelihoods are associated with poor mental-health outcomes².

Yet, global treaties, conventions and international-policy instruments treat mental health and the environment as separate domains. Mental health is rarely built into the reporting requirements, national implementation plans, financing criteria or accountability mechanisms of environmental conventions.

And environmental change is framed in treaties as a risk factor rather than as a core area of mental-health governance. For example, the 2013–30 agenda of the World Health Organization’s mental-health action plan recognizes that climate stability, healthy ecosystems, pollution control and sustainable land use shape the conditions in which people live, work and maintain their health³. But planning and monitoring systems for both domains remain disconnected. The Sustainable Development Goals (SDGs), too, lack indicators that integrate environmental and mental-health outcomes.

As a result, the implementation of environmental treaties is rarely considered to be part of measures that prevent mental-health conditions, and mental-health outcomes are seldom used to assess the success of environmental policies. What is needed is a practical bridge between these agendas: shared indicators, financing incentives, implementation guidance and accountability mechanisms that connect environmental governance to the prevention of mental-health conditions.

Here, we argue that environmental treaties such as the United Nations Framework Convention on Climate Change should be recognized as upstream policy instruments that shape mental health and psychosocial well-being before clinical intervention is needed⁴. The UN high-level political declaration recognizing the widespread burden of non-communicable diseases, including mental-health conditions, can become a basis for further action⁵.

To show the interconnected pathways, we propose, as a first step, a tiered policy framework that differentiates between environmental conventions according to their relevance for mental health and their readiness for indicator-based evaluation (see Supplementary information).

Making connections

To explore the relevance of global environmental conventions to mental health, we identified treaties across six related domains: chemicals and waste, biodiversity, climate and land, atmospheric protection, disaster-risk reduction and human rights.

For each convention, we assessed five dimensions: core governance objectives and regulatory mechanisms; plausible pathways to mental-health outcomes; the feasibility of tracking convention outcomes using existing mental-health and SDG indicators; the level of development and institutionalization; and the effectiveness of ratification and implementation.

Conventions were then grouped into three tiers on the basis of their core mandates’ alignment to mental-health outcomes and pathways to action (see ‘Global environmental conventions relevant to mental health’). A fourth, the cross-cutting tier, is linked to human rights.

Our aim is to encourage policymakers, programme developers and researchers to identify the cases for which mental-health integration into environmental governance is most actionable, and those for which further evidence, methods and accountability mechanisms are needed.

Tier 1: chemicals and hazardous waste. Conventions underpinning chemicals and hazardous waste have the clearest and most direct relevance to mental health. They regulate, for instance, neurotoxic chemicals, hazardous pesticides and toxic waste streams. These treaties have implications for neurodevelopment, cognitive function and suicide risk.

Tier 1 includes the Stockholm convention on pollutants, the Minamata Convention on Mercury, the Rotterdam convention on hazardous chemicals and pesticides, and the Basel Convention on the Control of Transboundary Movements of Hazardous Wastes and Their Disposal.

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Reducing exposure to mercury, lead, persistent organic pollutants and hazardous waste helps to protect brain development in young children. This protection is likely to result in long-term benefits for mental health, cognitive functioning and overall development⁶. Restricting hazardous pesticides also reduces access to lethal means for self-poisoning; evidence indicates that pesticide bans and restrictions can reduce pesticide-related suicides^7,8.

Tier-1 regimes are relatively well developed and widely ratified, with clear implementation mechanisms such as bans, phase-outs, emissions controls and waste-handling rules. The potential for developing paired indicators for mental health and chemicals or hazardous waste is high: rates of mortality from suicides, hospital admissions of people with poisoning, developmental delay and neurodevelopmental disability are measured widely and could serve as downstream indicators of treaty progress, provided that data are attributed and the data quality is maintained appropriately.

Tier 2: Rio conventions and disaster-risk reduction. These conventions focus on climate change (reducing greenhouse-gas emissions, conserving biodiversity and addressing desertification). The links to mental health are often more indirect than they are for chemical exposure. However, biodiversity- and climate-change-related issues have serious consequences at a population level.

Climate change, drought, land degradation, biodiversity loss and ecosystem disruption affect mental health by increasing people’s exposure to disasters, chronic stress and food insecurity, and raising their risk of being forced to migrate or losing their livelihood. Communities often don’t just value the world in terms of money; they might consider cultural values, sacred sites, human rights, health and ecological integrity — by valuing place, culture and nature⁹. For children and adolescents, environmental hazards lead to disrupted schooling, stressed families and carers, child-protection risks, displacement, loss of peer and community networks, and reduced access to health care, education and social services.

Tier 2 is anchored in the three Rio treaties — the Paris climate agreement, the UN Convention to Combat Desertification and the Convention on Biological Diversity — and complemented by the Sendai Framework for Disaster Risk Reduction. These are relevant to mental health mainly through psychosocial and livelihood-mediated pathways. The evidence base is substantial but more heterogeneous than it is for tier 1.

The Rio conventions have strong global legitimacy and broad ratification, yet implementation remains uneven. Related commitments provide platforms for action, for instance, through the Paris agreement’s Nationally Determined Contributions for emissions reductions, the UN’s plans to combat desertification and countries’ national adaptation plans, national biodiversity strategies and action plans. But nations’ ambition and efforts to follow through vary considerably⁴.

The potential for paired indicators is moderate: many relevant mental-health outcomes are already captured in existing data sets, but they are not routinely linked to environmental governance. Moreover, some are better suited to evaluating learning and programme performance than to accounting for treaty outcomes.

Tier 3: atmospheric protection. These conventions affect mental health indirectly and over the long term. By protecting the ozone layer and contributing to climate stability, the Vienna convention and Montreal Protocol might generate mental-health benefits through improved physical health, greater environmental security and more-stable social and economic conditions.

However, these effects are rarely conceptualized in mental-health outcomes, and current indicators do not allow for straightforward attribution. Some efforts have started to create links, but greater understanding is still needed.

Cross-cutting tier: promoting human rights. The conventions on the rights of children and people with disabilities provide an accountability framework for preventing mental-health conditions linked to the environment, ensuring equitable access to care and support and protecting people’s rights to development, participation in decision-making processes, education, health and not being discriminated against. This is especially important for children, adolescents, older people, individuals with disabilities, populations displaced by disasters, war or other hazards and communities facing cumulative environmental and social risks.