UNICEF - REACH Framework

Applying Behavioural Science to Address Environmental Health Threats Affecting Children Framework REACHFrameworkREACH 5 6 The REACH Framework was developed by Ukasha Ramli and Lisa Tanaka, social and behavioural scientists at UNICEF, with the support from the Healthy Environments for Healthy Children global programme, particularly Abheet Solomon and Katelyn Greer . The REACH Framework was informed by a social community listening study called Perception to Action. The authors would like to extend their sincere appreciation to UNICEF country offices that contributed feedback and supported piloting of the REACH materials. Their insights, experiences and commitment were instrumental in shaping and refining this framework. Disclaimer All reasonable precautions have been taken by UNICEF to verify the information contained in this publication. However , the published material is being distributed without warranty of any kind, either expressed or implied. The responsibility for the interpretation and use of the material lies with the reader . In no event shall UNICEF be liable for damages arising from its use. Acknowledgements © United Nations Children’s Fund (UNICEF) June 2026

Suggested citation: United Nations Children’s

Fund, REACH Framework: Applying Behavioural Science to Address Environmental Health Threats Affecting Children , UNICEF, New York, June 2026. https://ceh.unicef.org/events-andresources/knowledge-library/reach-guideapplying-behavioural-science-environmental Social and Behaviour Change Climate & Environment Global Practice UNICEF Global Programme Division www.unicef.org www.sbcguidance.org Cover photos: 1. © UNICEF/UNI912240/Pouget 2. © UNICEF/UNI828059/Phiennachit 3. © UNICEF/UNI692356/Ijazah 4. © UNICEF/UNI907174/Rojas 5. © UNICEF/UNI925371/Bortkevych 1 2 34 5 iiAcknowledgements ii Acronyms and abbreviations iv Executive summary 1 The challenge 4

4. © UNICEF/UNI907174/Rojas 5. © UNICEF/UNI925371/Bortkevych

1 2 34 5 iiAcknowledgements ii Acronyms and abbreviations iv Executive summary 1 The challenge 4 1.1 Environmental health threats as a crisis for children 4 Characteristics of environmental threats that 6 inhibit responses 2.1 Threat characteristics 6 2.2 From characteristics to response 8 Responses to environmental health threats 10 3.1 Monitoring 11 3.2 Protective action 12

REACH Framework: A behavioural lens for 15 message re-design 4.1 Recognize 16

Making the invisible visible 4.2 Engage 20 Motivation and priority 4.3 Act 24 Enabling protective behaviour 4.4 Context 30 Conditions for delivery and impact 4.5 Habit 35 Conditions for sustained behaviour How to use the REACH Framework 39 Conclusion 45 References 46 1 2 3 4 5 6

Contents Cover photos: 1. © UNICEF/UNI912240/Pouget 2. © UNICEF/UNI828059/Phiennachit 3. © UNICEF/UNI692356/Ijazah 4. © UNICEF/UNI907174/Rojas 5. © UNICEF/UNI925371/BortkevychFrameworkREACH

AJPH American Journal of Public Health CCT Cultural Cognition Theory COM-B capability, opportunity, motivation – behaviour model ECO ecological-social model EPA Environmental Protection Agency HBM health belief model HEPA high-efficiency particulate air HAP heat action plan HAPIN Household Air Pollution Intervention Network IAP indoor air pollution LPG liquefied petroleum gas NO₂ nitrogen dioxide ORS oral rehydration solution PM2.5 particulate matter ≤2.5 micrometres PMT protection motivation theory

HAP heat action plan HAPIN Household Air Pollution Intervention Network IAP indoor air pollution LPG liquefied petroleum gas NO₂ nitrogen dioxide ORS oral rehydration solution PM2.5 particulate matter ≤2.5 micrometres PMT protection motivation theory PMUY Pradhan Mantri Ujjwala Yojana (India LPG Programme) PPE personal protective equipment SBC social and behaviour change SMS short message service TSCA Toxic Substances Control Act UNICEF United Nations Children’s Fund WHO World Health Organization XRF X-ray fluorescence Acronyms and abbreviations ivEnvironmental health threats are exposures and conditions where children live, learn and play that increase the risk of disease, injury or impaired development. They include air pollution from household cooking fuels, traffic, industry and waste-burning; lead and other toxic substances in food, water , soil and consumer products; extreme heat and climate-driven hazards such as floods and wildfires; and chemical contaminants from pesticides, industrial processes and informal recycling. Children face disproportionate risk because they have a higher metabolic rate than adults and eat more than adults relative to body weight, some of their detoxification systems may be immature, and their bodies and brains are undergoing rapid development when environmental exposures can cause irreversible damage. Nearly 92 per cent of pollution-related child deaths occur in lowand middle-income countries, and the populations most heavily exposed are often those with the fewest resources to respond. Despite their diversity, these threats share key characteristics: • imperceptibility • delayed effects (months or years) • indirect causal pathways • perceived lack of individual control • competition with immediate daily pressures These factors make them systematically difficult to respond to from a behavioural perspective. Protective responses fall into two categories: • monitoring (detecting and tracking threats through environmental measurement, biological testing, and symptom recognition) • protective action (reducing contact with hazards through avoidance behaviours, physical barriers and, ideally, through regulatory interventions).

Protective responses fall into two categories: • monitoring (detecting and tracking threats through environmental measurement, biological testing, and symptom recognition) • protective action (reducing contact with hazards through avoidance behaviours, physical barriers and, ideally, through regulatory interventions). These are components of a feedback system rather than independent activities: monitoring generates the information that guides protective action, and the outcomes of protective action can be assessed through ongoing monitoring. Executive summary

© UNICEF/UNI789749/Mukut

1 FrameworkREACHFrameworkREACH Executive summary The approach is organized around the REACH Framework: When exposure occurs, health-seeking behaviours become necessary. Because many environmental health harms are irreversible once they occur , upstream action to reduce exposure takes precedence. A persistent gap exists between the availability of protective behaviours and their successful, sustained adoption. Regulations exist to reduce lead exposure, but enforcement is inconsistent and industries continue to pollute. Programmes subsidize clean cookstoves, but some families prefer traditional methods for culturally valued dishes. 1,2 Workers understand the risks of heat exposure but cannot prioritize rest breaks when income depends on continuous labour . This guide provides a structured approach to diagnosing the behavioural and structural barriers that produce these gaps, and to designing interventions that address them. It draws examples from across environmental health challenges, including air pollution, lead contamination, extreme heat, pesticide exposure and water contamination. Recognize addresses the detection, understanding and interpretation of invisible threats through sensory enhancement, causal understanding and risk calibration. Engage creates personal relevance and emotional connection for environmental health protection through competing daily priorities using personalization, value-aligned framing and social influence. Act enables consistent protective behaviour through capability-building, confidence and collective efficacy. Context addresses the structural and contextual conditions that determine intervention effectiveness. Habit ensures protective behaviour persists through routines, cues and environmental design that sustain automatic responses.

framing and social influence. Act enables consistent protective behaviour through capability-building, confidence and collective efficacy. Context addresses the structural and contextual conditions that determine intervention effectiveness. Habit ensures protective behaviour persists through routines, cues and environmental design that sustain automatic responses. 2The guide concludes with a three-phase application process: 1. understanding the situation through a diagnostic assessment of each REACH component 2. deciding where to focus, based on the severity of barriers and the leverage available 3. designing an integrated intervention that sequences individual-facing and structural approaches. A worked example (lead contamination near a battery recycling site) illustrates the process throughout. The framework does not prescribe a fixed sequence. The entry point and emphasis depend on the specific pattern of barriers in each context, and the guide is designed to support that judgment rather than replace it. Figure 1 The REACH Framework Executive summary Making the invisible visible Conditions for delivery and impact Conditions for sustained behaviour Motivation and priority Enabling protective behaviour Interventions Conditions for delivery and sustainability Recognize Context Habit Engage Act 3 FrameworkREACHFrameworkREACH Environmental health threats as a crisis for children 1.1 Environmental health threats are exposures and conditions in the environments where children live, learn and play that increase the risk of disease, injury or impaired development. They range from pollutants circulating invisibly through air , water , soil, food and consumer products, to climatedriven hazards such as extreme heat, floods and wildfires. These threats are not evenly distributed: nearly 92 per cent of pollution-related child deaths occur in lowand middle-income countries, and the populations most heavily exposed are often those with the fewest resources to respond. The Children’s Environmental Health Collaborative provides comprehensive information on the full landscape of risks. The categories below establish the scope and character of the threats addressed in this guide and the behavioural challenges they pose. Pollution Air pollution is the single greatest environmental health threat to children. Two thousand children aged under five years die each day from air

provides comprehensive information on the full landscape of risks. The categories below establish the scope and character of the threats addressed in this guide and the behavioural challenges they pose. Pollution Air pollution is the single greatest environmental health threat to children. Two thousand children aged under five years die each day from air pollution-related health impacts, accounting for 15 per cent of all global child deaths.3 Sources include polluting household cooking fuels, traffic and industrial emissions, waste-burning (including plastics), and wildfires and dust storms. Fine particulate matter penetrates deep into developing lungs and crosses into the bloodstream, with exposure during pregnancy linked to preterm birth and stillbirth, and early childhood exposure linked to lasting cognitive, behavioural and social impairments. Lead, toxic substances and chemical contaminants represent a second major pollution pathway. Around one in three children globally has blood lead levels high enough to cause harm,4 with exposure entering through contaminated food, spices, cosmetics, cookware and poorly regulated waste and recycling operations, including informal battery or e-waste processing near residential areas. Lead is one of a broader set of hazards, including mercury, arsenic, pesticides and industrial chemicals, whose effects are cumulative, often invisible, and may only become apparent years after exposure. Housing conditions such as deteriorating lead paint, inadequate sanitation and proximity to industrial sites further shape children’s baseline exposure. Climate change Climate change is intensifying hazards that directly threaten children’s health. Extreme heat is an escalating risk: young children generate more internal heat relative to body mass, and depend on caregivers to manage their exposure, making them susceptible to dehydration, heat exhaustion and heatstroke.5 Wildfires, floods and extreme weather are increasing in frequency and severity, destroying critical infrastructure, contaminating water supplies and producing dangerous air pollution far from the event itself. Weather-related disasters have displaced at least 43 million children over a sixyear period.6 Unlike most forms of pollution, many

are increasing in frequency and severity, destroying critical infrastructure, contaminating water supplies and producing dangerous air pollution far from the event itself. Weather-related disasters have displaced at least 43 million children over a sixyear period.6 Unlike most forms of pollution, many climate-driven threats are sudden-onset and time limited, demanding rapid preparedness and response rather than sustained avoidance.

1. The challenge

© UNICEF/UNI956992/Rasnat 4Why children are uniquely vulnerable Across both categories, children face disproportionate risk. Young children have a higher metabolic rate than adults and inhale a greater amount of air relative to their body weight, meaning that, for a given concentration of airborne pollutant, a child’s effective dose is higher .7 They eat and drink more per kilogram of body mass than adults, amplifying ingestion of contaminants in food and water . Hand-to-mouth behaviour in early childhood, a normal and necessary part of sensory exploration, can be a direct route of exposure when dust, soil or household surfaces carry toxic residues. A young child in a lead-contaminated environment may ingest soil and dust dozens of times per day, each instance delivering a small but cumulative dose.8 Children’s bodies process toxicants differently than adults’ bodies. Some detoxification enzymes in the liver are functionally immature in the first years of life, reducing the body’s capacity to metabolize and excrete certain substances.9 The blood-brain barrier , which in adults provides partial protection against some toxicants, is not fully matured and more fragile in infants with different permeability properties. The gastrointestinal tract absorbs a greater fraction of ingested metals; children absorb approximately 40 to 50 per cent of dietary lead, compared with 3 to 10 per cent in adults. 10 The most consequential vulnerability, however , is developmental. More than 90 per cent of brain architecture is established in the first five years of life, a period of rapid neuronal proliferation, migration and synapse formation. Environmental

compared with 3 to 10 per cent in adults. 10 The most consequential vulnerability, however , is developmental. More than 90 per cent of brain architecture is established in the first five years of life, a period of rapid neuronal proliferation, migration and synapse formation. Environmental exposures during these critical windows can redirect developmental trajectories entirely. Lead exposure in early childhood provides an illustration. There is no safe level of lead exposure for children. 11 Blood lead concentrations as low as 5 μg/dL are associated with measurable reductions in IQ, and each additional microgram of exposure can cause greater harm at lower concentrations than at higher ones.12 Some cognitive deficits can persist into adulthood, affecting educational attainment, earning potential and impulse regulation decades after the original exposure. The lungs tell a similar story. Children’s airways are narrower and still developing alveolar structures well into adolescence. Prenatal exposure to fine particulate matter (PM2.5) is associated with reduced forced expiratory volume in the first second of life, a deficit of approximately 55 millilitres per 10 micrograms per cubic metre of exposure.13 Postnatal exposure during the first years compounds this: children growing up in highly polluted areas show measurably stunted lung growth, a deficit they carry into adulthood as reduced respiratory reserve.14 Ambient air pollution contributes to an estimated 15.6 per cent of lowbirth-weight deliveries globally,15 with consequences that cascade through infancy and beyond. What makes these vulnerabilities urgent rather than merely concerning is their irreversibility. Unlike many adult health effects, for which the body can partially compensate once exposure ceases, developmental damage sustained in the early years may be permanent. A child whose neural development is disrupted by lead at age two does not recover that lost capacity at age

10. A child whose lungs fail to reach full growth potential by adolescence, enters adulthood with diminished respiratory function that no subsequent intervention can fully restore. This is

early years may be permanent. A child whose neural development is disrupted by lead at age two does not recover that lost capacity at age

10. A child whose lungs fail to reach full growth potential by adolescence, enters adulthood with diminished respiratory function that no subsequent intervention can fully restore. This is the fundamental asymmetry that distinguishes environmental health threats to children from those facing adults: the damage may not be proportional to the dose, sometimes it is not reversible, and it is not confined to the period of exposure. It can shape an entire life.

1. The challenge

5 FrameworkREACHFrameworkREACH

2. Characteristics of environmental threats that inhibit responses Threat characteristics2.1

Sensory imperceptibility and normalization Many of the most dangerous environmental health threats cannot be detected by human senses. Fine particulate matter (PM2.5) is invisible to the naked eye. Lead contamination in water , soil, food and consumer products is tasteless, odourless and invisible. Many toxic chemicals in household products and building materials give no sensory warning. Even threats that produce some sensory signal often fail to communicate their true danger: air that smells clean may carry dangerous concentrations of pollutants, and water that appears clear may contain harmful levels of dissolved metals. This imperceptibility creates a fundamental behavioural problem. Human protective instincts evolved to respond to perceivable dangers. Threats that cannot be seen, smelled, tasted or felt do not trigger the automatic alarm responses that drive the avoidance of visible hazards. Without sensory evidence of danger , people systematically Environmental health threats affecting children are shaped by common characteristics that make effective responses particularly challenging. Understanding these characteristics explains why awareness campaigns and conventional health messaging frequently fail to produce protective behaviour . Where a visible, immediate and clearly caused threat like a venomous snake triggers automatic protective instincts, environmental health threats systematically undermine the psychological foundations on which protective behaviour depends. underestimate risk. This means that, even where

and conventional health messaging frequently fail to produce protective behaviour . Where a visible, immediate and clearly caused threat like a venomous snake triggers automatic protective instincts, environmental health threats systematically undermine the psychological foundations on which protective behaviour depends. underestimate risk. This means that, even where people are aware in principle that a threat exists, they lack the moment-to-moment perceptual feedback needed to guide protective decisions. A related but distinct problem affects threats that are perceptible but constant. Extreme heat, persistent smog or chronic noise pollution may be experienced daily, yet their very ubiquity can cause them to fade into the background of ordinary life. When a whole community shares the same exposure, as during a prolonged heat wave or in a neighbourhood with persistently poor air quality, there is no contrast against which to recognize the abnormality of the situation. The threat becomes normalized: acknowledged in the abstract but no longer treated as something requiring a response. This normalization differs from invisibility but produces a similar behavioural outcome. People may not act on dangers they have come to regard as part of the fabric of daily life and may struggle to take appropriate precautions when conditions have crossed from uncomfortable to genuinely dangerous. © UNICEF/UNI972847/Palazón 6Temporal disconnection For many environmental health threats, the interval between exposure and harm is measured in months, years or decades. Lead exposure in early childhood produces neurodevelopmental damage that may not become apparent until a child reaches school age. Chronic air pollution exposure contributes to respiratory and cardiovascular disease that develops over years. Accumulated exposure to pesticides or industrial chemicals may only manifest as illness long after the period of contact. This temporal gap breaks the feedback loop that normally sustains health-protective behaviour . When a person touches a hot surface, the immediate pain teaches them to avoid it in future. When exposure to a pollutant produces no perceptible consequence for years, the connection between action and outcome becomes invisible. This disconnection undermines

normally sustains health-protective behaviour . When a person touches a hot surface, the immediate pain teaches them to avoid it in future. When exposure to a pollutant produces no perceptible consequence for years, the connection between action and outcome becomes invisible. This disconnection undermines motivation for sustained protective effort, because it is difficult to maintain vigilance against a danger that produces no immediate evidence of harm. The temporal dimension also operates in reverse. Some threats, such as extreme heat events, wildfires or acute pollution episodes are sudden-onset and require rapid response. The challenge in these cases is the compressed decision-time rather than delayed consequences; preparedness and response behaviours must already be in place before the event occurs, because the window for action is narrow. Causal complexity and uncertainty The pathways from environmental exposure to health outcome are often indirect, multi-causal and difficult to verify from personal experience. A child’s developmental delay may have multiple contributing factors, of which lead exposure is only one. A respiratory illness may reflect the combined effects of indoor air pollution, outdoor air quality, occupational exposure and individual vulnerability. This causal complexity makes it difficult for individuals to attribute health problems to environmental causes, even when the epidemiological evidence is clear . Uncertainty operates at multiple levels. At an individual level, exposure does not produce identical outcomes in all people, and this is especially the case for children at different ages. Some individuals and children exposed to the same concentration of a pollutant will develop illness while others will not, making it easy to dismiss the risk as inapplicable. In particular , younger children are at higher risk due to their immature body systems and rapid development. At community level, the uneven and unpredictable (probabilistic) nature of environmental health harm means that even welldocumented tragedies, such as mass lead poisoning events, have only become apparent when entire populations showed disproportionate rates of illness or developmental problems. Moreover , conflicting messages from different sources about the severity

uneven and unpredictable (probabilistic) nature of environmental health harm means that even welldocumented tragedies, such as mass lead poisoning events, have only become apparent when entire populations showed disproportionate rates of illness or developmental problems. Moreover , conflicting messages from different sources about the severity of threats can create confusion that is easily resolved by inaction. Perceived controllability Many environmental health threats appear to originate from sources beyond the control of individuals and households. Air pollution comes from many sources, such as traffic, industry and waste-burning. Water contamination may reflect infrastructure failures or upstream industrial discharge. Chemical exposures may stem from unregulated manufacturing or supply-chain contamination. When the source of a threat seems systemic, people may conclude that personal or household action is futile, leading to a sense of helplessness that suppresses protective behaviour even where meaningful individual-level actions exist. This perception has some basis. Some environmental health challenges require policy, regulatory or infrastructure responses that individuals cannot provide. A household cannot regulate factory emissions or reform a contaminated water supply. But the conclusion that personal action is therefore pointless is a behavioural trap. Household and individual actions, such as using water filters, choosing safer products, timing outdoor activities or wearing protective equipment, can meaningfully reduce exposure even while systemic problems persist. The challenge for intervention design is to support individual

2. Characteristics of environmental threats that inhibit responses

7 FrameworkREACHFrameworkREACH protective action without implying that systemic change is unnecessary, or that the burden of protection should fall on those least responsible for the hazard. Additionally, in some circumstances, citizen action can also be an effective way to move towards obtaining government regulations to deal with polluters. Competing priorities Environmental health threats rarely exist in isolation from other pressures. Households facing poverty, food insecurity or lack of employment must allocate scarce time, money and attention across competing demands. An invisible, slow-acting environmental

towards obtaining government regulations to deal with polluters. Competing priorities Environmental health threats rarely exist in isolation from other pressures. Households facing poverty, food insecurity or lack of employment must allocate scarce time, money and attention across competing demands. An invisible, slow-acting environmental hazard will almost always lose this competition against visible, immediate needs. A mother may understand that indoor smoke from cooking harms her children. If the alternative fuel is unaffordable or unavailable, that knowledge cannot translate into action. A family living near an informal recycling operation recognizes the health risks while depending on that income for their livelihood. This competition reflects structural conditions (poverty, inadequate infrastructure, weak regulation, gender dynamics and limited access to alternatives) that constrain available choices, not only individual prioritization. The populations most heavily exposed to environmental health threats are often those with the fewest resources to respond. Communities in informal settlements near industrial sites, workers in hazardous occupations without adequate protection, and families relying on contaminated water supplies face disproportionate exposure and disproportionate barriers to action. Where exposure is highest, the conditions for behaviour change are most often absent. From characteristics to response2.2 These characteristics interact and compound the problem. A threat that is both imperceptible and temporally disconnected is harder to respond to than one that is merely invisible but produces immediate symptoms. A hazard that appears uncontrollable and competes with more pressing survival needs generates even less protective motivation than one that is invisible but within perceived control. The cumulative effect is a set of threats that are systematically biased against behavioural response; the features that would normally trigger and sustain protective action are absent. These characteristics also explain why conventional health communication approaches are often insufficient. Awareness campaigns that inform people about the existence of a threat do not solve the perception problem if the threat remains invisible or normalized in daily experience. Messaging that emphasizes severity can produce fatalism rather than action if people

are absent. These characteristics also explain why conventional health communication approaches are often insufficient. Awareness campaigns that inform people about the existence of a threat do not solve the perception problem if the threat remains invisible or normalized in daily experience. Messaging that emphasizes severity can produce fatalism rather than action if people feel unable to control the source. Information about protective behaviours is ineffective if structural barriers make those behaviours inaccessible. The following section describes some categories of protective behaviour that can reduce harm from environmental health threats: monitoring (detecting and tracking threats) and protective action (reducing contact with hazards). The REACH Framework in Section 4 then provides a structured approach to designing interventions that address the behavioural and structural barriers to adopting and maintaining these behaviours.

2. Characteristics of environmental threats that inhibit responses

8Environmental health threat Figure 2 Environmental threats: Why they are so difficult to tackle

2. Characteristics of environmental threats that inhibit responses You see the snake. Fear response is automatic. No technology or training needed to detect the danger .

A snakebite causes instant pain. The cause-effect link is unmissable. Avoidance learning is rapid. Snake bite pain illness. One cause, one pathway, no ambiguity. Move away f