UNICEF - Noise and Children's Health

Executive summary Noise (defined as unwanted and/or harmful sound) is a preventable environmental health hazard that undermines children’s health and key protective factors for their development, including sleep, learning and emotional well-being. Children are particularly vulnerable to the impacts of noise owing to a combination of physiological, developmental and behavioural factors. Their auditory systems are still developing, and their ear canals may transmit sounds differently from those of adults. Children spend more time asleep than adults, and their sleep architecture is more easily disrupted. Young children rely heavily on clear and consistent auditory input to acquire language skills, interpret social cues, build meaningful connections with others and develop cognitive and social-emotional skills, particularly during sensitive periods of experiencedependent brain development, when neural circuits are shaped by environmental stimuli. Hearing loss is unlikely to occur from environmental noise exposure, but it can occur from leisure-related (recreational) noise exposure. Special attention should be paid to the effects of recreational noise exposure on children and adolescents; the World Health Organization (WHO) estimates that more than 1 billion young people risk hearing loss based on their listening habits. Hearing loss can negatively affect school achievement, contribute to social isolation and diminish long-term economic opportunities. Although environmental noise is unlikely to cause hearing loss, it has many other effects on health, and children across the globe, particularly those living in urban, industrial or low-income environments, are exposed to environmental noise levels that exceed health-based guidelines. WHO recommends that average noise levels in classrooms should not exceed 35 decibels, while night-time noise in residential areas should remain below 40 decibels to protect sleep. Daytime average exposure should not exceed 55 decibels in residential zones. Noise must be controlled at the source. Caregivers can limit children’s exposure to loud toys, devices and digital media. Communities can locate schools and childcare facilities away from major roads, airports, railways and industrial zones. Noise considerations can be

55 decibels in residential zones. Noise must be controlled at the source. Caregivers can limit children’s exposure to loud toys, devices and digital media. Communities can locate schools and childcare facilities away from major roads, airports, railways and industrial zones. Noise considerations can be incorporated into land use planning, transport policies and building regulations. Reducing excessive noise is essential not only for public health, but also for upholding children’s rights to clean, healthy and sustainable environments. Many noise reduction strategies, such as limiting traffic near schools or redesigning flight paths to avoid community public spaces and residential areas, also reduce air and light pollution. Because traffic-related noise and air pollution share common sources, coordinated action can yield broad public health and environmental benefits. Creating quieter , healthier environments for children is an investment in equity and the future. NOISE AND CHILDREN’S HEALTHIntroduction Noise is defined as unwanted and/or harmful sound (Fink, 2023) and is often dismissed as a minor environmental irritant. The effects of occupational noise on workers’ hearing have been known for centuries, but there is growing evidence of the effects of environmental and recreational noise on children. The World Health Organization (WHO) defines environmental noise as noise from all sources with the exception of workplace (occupational) noise. Leisure-related (recreational) noise is defined as noise that a person intentionally exposes themself to as part of recreational activities, such as listening to loud music or participating in other leisure pursuits that can lead to noise exposure (World Health Organization, 2022). This document focuses primarily on environmental noise, also known as 'noise pollution'. Chronic or excessive environmental noise is a serious threat to children’s health and development. Noise interferes with sleep, concentration, communication and emotional regulation, while also activating physiological stress responses (Balk et al., 2023). Therefore, noise exposure should be recognized as an urgent environmental child health issue at the individual,

threat to children’s health and development. Noise interferes with sleep, concentration, communication and emotional regulation, while also activating physiological stress responses (Balk et al., 2023). Therefore, noise exposure should be recognized as an urgent environmental child health issue at the individual, community and global levels. Children across the globe, particularly those living in urban, industrial or low-income environments, are exposed to environmental noise levels that exceed health-based guidelines. Among European children, transport noise is estimated to cause over half a million cases of reading difficulties, 63,000 cases of behavioural problems and about 272,000 cases of overweight (European Environment Agency, 2025). Classroom noise, especially in under-resourced schools near busy roads or with poor infrastructure, can further compound exposure during key learning periods. Sources of exposure Population growth, urbanization and technological development are the main driving forces of excessive environmental noise (World Health Organization, 1999). Rural areas also are affected by new sources of noise, such as large wind farms, industrial-scale farming and increased freight transport. Rural noise affects adults and children worldwide (Woudenberg & van Kamp, 2025). Moreover , human-made noise, such as traffic, can mask the beneficial effects of natural sounds like birdsong in reducing stress and anxiety (Gilmour et al., 2024). 2Noise affects children across multiple settings: • Home environments may be affected by ambient outdoor noise (e.g., from road traffic, neighbours, industry, railways, air traffic, wind turbines, building sites) and noise from indoor sources such as room acoustics or activities of other occupants (e.g., from televisions, loud appliances, overcrowding or domestic conflict) (World Health Organization, 2022). The nature and extent of these exposure pathways vary depending on building design and location (World Health Organization, 2009). • School settings often lack soundproofing and are frequently located near traffic corridors or other

domestic conflict) (World Health Organization, 2022). The nature and extent of these exposure pathways vary depending on building design and location (World Health Organization, 2009). • School settings often lack soundproofing and are frequently located near traffic corridors or other industrial/anthropogenic noise. Internal sources, such as overcrowded classrooms and poor acoustics, also contribute to noise. The European Environment Agency estimates that half a million schoolchildren suffer learning impairment in school because of noise (European Environment Agency, 2025). • Community environments, including playgrounds, streets and housing near transport infrastructure (aircraft, road and rail), can expose children to fluctuating and unpredictable noise levels. Neighbours operating machinery or playing loud music may elevate exposure in both the home and community settings. • Leisure activities, involving the use of personal devices such as headphones or toys that emit loud sounds, can expose even very young children to harmful recreational noise levels close to the ear canal. Children and adolescents may be exposed to excessively loud noises at celebratory, recreational, and, sports events. Young children must rely on adults to remove them from such situations. Exposure pathways Children are particularly vulnerable to the impacts of noise, owing to a combination of physiological, developmental and behavioural factors: • Children’s auditory systems are still developing, and their ear canals may transmit sounds differently from those of adults (Kruger , 1987). • Children spend more time asleep than adults, and their sleep architecture is more easily disrupted. • Young children rely heavily on clear and consistent auditory input to acquire language skills, interpret social cues, build meaningful connections with others and develop cognitive and social-emotional skills, particularly during sensitive periods of experience-dependent brain development, when neural circuits are shaped by environmental stimuli (Tierney & Nelson, 2009; Kuhl, 2010). • Children have different perceptions of noise from adults, cannot control their environment and

skills, particularly during sensitive periods of experience-dependent brain development, when neural circuits are shaped by environmental stimuli (Tierney & Nelson, 2009; Kuhl, 2010). • Children have different perceptions of noise from adults, cannot control their environment and may be more exposed to noise because of their exploratory behaviour (United Nations Children’s Fund & World Health Organization, 2024). The stress of chronic noise exposure can affect emotional regulation, leading to behavioural difficulties and diminished mental well-being. Hearing loss is unlikely to occur from environmental noise exposure, but it can occur from leisure-related (recreational) noise exposure. Special attention should be paid to the effects of recreational noise exposure on children and adolescents, since hearing loss can negatively affect school achievement, contribute to social isolation and diminish long-term economic opportunities (Roberts & Neitzel, 2018). Certain subgroups of children may be particularly at risk of harm from excessive noise exposure, including infants born prematurely; children with dyslexia, hyperactivity or autism spectrum disorder; and children given ototoxic medications (prescription drugs that affect the delicate structures of the inner ear) (World Health Organization, 2019). Children’s unique vulnerability 3The decibel (dB) is a measure of the intensity or loudness of sound. Decibels are used to express sound on a compressed, logarithmic scale in the human audible spectrum. WHO recommends that average noise levels in classrooms should not exceed 35 dB (World Health Organization, 1999), while night-time noise in residential areas should remain below 40 dB (World Health Organization Regional Office for Europe, 2009) to protect sleep. Daytime average exposure should not exceed 55 dB in residential zones. However , studies consistently find that many children are exposed to levels that far exceed these thresholds. In some classrooms and urban housing, noise levels regularly reach 70–80 dB, posing a significant risk to health and learning. Hearing can also be impacted

exposure should not exceed 55 dB in residential zones. However , studies consistently find that many children are exposed to levels that far exceed these thresholds. In some classrooms and urban housing, noise levels regularly reach 70–80 dB, posing a significant risk to health and learning. Hearing can also be impacted at these levels depending on the amount of time of exposure. Children and adolescents also are affected by leisure-related noise exposure; WHO estimates that more than 1 billion young people risk hearing loss based on their recreational listening habits (World Health Organization & International Telecommunication Union, 2019). Unlike traditional noise limits that focus solely on decibels, WHO’s health-based standards are grounded in evidence linking specific noise exposure pathways to adverse health outcomes. While decibel rules measure intensity, they often ignore factors such as exposure timing, duration, population vulnerability and nonauditory effects. WHO guidelines set lower thresholds based on systematic reviews of evidence linking noise exposure to adverse health effects in the general population, rather than focusing solely on noise nuisance. Reference values and guidelines WHO noise guidelines: Key points for policy and practice The WHO Environmental Noise Guidelines for the European Region (World Health Organization, 2018) provide recommended exposure levels and policy measures to protect populations – including children – from the harmful health effects of noise originating from various sources: transport (road traffic, railway and aircraft) noise, wind turbine noise and leisure-related noise. Older guidelines, such as the indoor values from the Guidelines for Community Noise (World Health Organization, 1999) and the Night Noise Guidelines for Europe (World Health Organization Regional Office for Europe, 2009), remain technically valid but should not be used in isolation. Readers are encouraged to consult the Environmental Noise Guidelines for the European Region (World Health Organization, 2018) for comprehensive guidance. When referencing guideline values, it is important to indicate the specific acoustic indicators used, as these can vary across jurisdictions. The 2018 Environmental Noise Guidelines for the European Region include a glossary of acoustic terms to support consistent interpretation.

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European Region (World Health Organization, 2018) for comprehensive guidance. When referencing guideline values, it is important to indicate the specific acoustic indicators used, as these can vary across jurisdictions. The 2018 Environmental Noise Guidelines for the European Region include a glossary of acoustic terms to support consistent interpretation.

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NOISE GUIDELINES for the European Region 4Europe: Aircraft noise and reading delays A cohort study of over 2,800 children aged 9 or 10 years across primary schools near Heathrow Airport (United Kingdom), Madrid-Barajas Airport (Spain) and Schiphol Airport (Kingdom of the Netherlands) found that chronic exposure to aircraft noise was significantly associated with delayed reading comprehension and impaired memory performance (World Health Organization, 2019). Each 5 dB increase in aircraft noise was linked to a two month delay in reading age among children in schools near Heathrow Airport in London and a one month delay in reading age among children in schools near Schiphol Airport in the Netherlands; there were no national data available for Spain. The effect was independent of socio-economic status or classroom noise (Stansfeld et al., 2005). The effects were consistent and dose dependent, underscoring the long-term cognitive costs of unmitigated environmental noise.

Policy insight: Strategic zoning, insulation and airport operation restrictions during school hours can protect learning outcomes for children in high-exposure areas.

Health impacts Direct damage and indirect health impacts from excessive noise exposure are modified by sound characteristics, including vibration, frequency, intensity, and duration (World Health Organization, 2019). Neurological and cognitive development Noise exposure, particularly in schools and densely populated areas, interferes with executive functioning and language processing. Chronic exposure is associated with poorer reading comprehension, delayed language acquisition and reduced academic achievement due to altered attention, concentration, and memory (Stansfeld et al., 2005; Clark & Paunovic, 2018). Neurodevelopmental effects may be especially pronounced when exposure occurs during sensitive windows of brain maturation, with some studies

delayed language acquisition and reduced academic achievement due to altered attention, concentration, and memory (Stansfeld et al., 2005; Clark & Paunovic, 2018). Neurodevelopmental effects may be especially pronounced when exposure occurs during sensitive windows of brain maturation, with some studies suggesting alterations in hippocampal and prefrontal cortex function (Basner et al., 2014). New York City, NY, USA: Classroom noise and learning inequity In a study of schools located adjacent to elevated subway lines in the Bronx (Bronzaft & McCarthy, 1975), children in classrooms facing a subway line had lower reading scores and higher rates of teacher-reported distraction than peers in quieter classrooms. The ambient subway noise exceeded 90 dB when subway trains passed, occurring approximately every 4.5 minutes. Once classrooms were fitted with acoustic insulation and soundproof windows, children’s reading scores improved to match those of children in unaffected classrooms (Bronzaft, 1981).

Policy insight: Environmental noise contributes to educational inequity. Infrastructure investment in soundproofing schools can reduce disparities in learning outcomes for low-income and marginalized students.

5Munich, Germany: Noise-induced behavioural problems Following the relocation of Munich’s airport, researchers conducted a natural experiment measuring children’s stress biomarkers and behaviour before and after the airport was moved (Evans et al., 1995). Children who lived near the old airport site showed decreased cortisol levels and fewer behavioural problems one year after the noise source was removed. Conversely, children who had recently become exposed to aircraft noise at the new site experienced increased stress levels, worsened sleep and elevated signs of hyperactivity and inattention.

Policy insight: Noise exposure is reversible – mitigation efforts such as relocation, insulation, and zoning can yield measurable improvements in children’s mental health within months.

Sleep health Noise disrupts both sleep duration and architecture, even when it does not cause full arousal. In children, disturbed sleep is linked to impaired memory consolidation, weakened immune response and poor emotional regulation (World Health Organization, 2018).

Sleep health Noise disrupts both sleep duration and architecture, even when it does not cause full arousal. In children, disturbed sleep is linked to impaired memory consolidation, weakened immune response and poor emotional regulation (World Health Organization, 2018). Emotional and behavioural regulation Prolonged exposure to noisy environments increases the risk of emotional and behavioural disturbances (Raess et al., 2022). Studies report higher rates of anxiety, aggression, irritability, and symptoms of hyperactivity among children living or learning in high-noise settings. (Crombie et al., 2011). For example, a systematic review of studies published across four different databases found that, for every 10 dB increase in road traffic noise, children’s risk of hyperactivity increases by 11 per cent (Schubert et al., 2019). These outcomes may be mediated by both direct activation of the body’s stress response systems and indirect effects such as sleep fragmentation and reduced coping capacity. Auditory health While most ambient noise levels do not cause immediate hearing loss, specific sources – including loud toys, personal listening devices, infant sleep machines ('white noise machines') (Hugh et al., 2014; Hong et al., 2021) and fireworks – can exceed safe thresholds. Sound-producing toys have been recorded at 85–100 dB at close range – levels that can damage the developing auditory system (noise-induced hearing loss) with prolonged or repeated exposure (Balk et al., 2023). Such exposure is particularly concerning in preverbal children, for whom hearing impairment can delay language development and social engagement (Balk et al., 2023). Cardiovascular and endocrine effects Noise acts as a chronic environmental stressor by activating the sympathetic-adrenal-medullary system and the hypothalamic-pituitary-adrenal axis. The technical report Biological Mechanisms Related to Cardiovascular and Metabolic Effects by Environmental Noise highlights the biological pathways that contribute to cardiovascular and metabolic diseases in adults

activating the sympathetic-adrenal-medullary system and the hypothalamic-pituitary-adrenal axis. The technical report Biological Mechanisms Related to Cardiovascular and Metabolic Effects by Environmental Noise highlights the biological pathways that contribute to cardiovascular and metabolic diseases in adults attributable to noise (World Health Organization Regional Office for Europe, 2018). Even in childhood, repeated noise exposure is associated with elevated cortisol levels, increased systolic blood pressure and reduced heart rate variability (Babisch, 2011). These early markers of physiological stress give rise to concerns about long-term risk for cardiometabolic diseases and underscore the importance of early-life prevention. Social and behavioural effects Excess noise disrupts children’s ability to communicate and engage socially. In both home and school settings, background noise can interfere with speech perception, making it difficult for children to follow conversations, respond appropriately and fully participate in group activities. 6Intervention and mitigation strategies Addressing noise as a children’s health issue requires coordinated action at multiple levels, from caregivers to national policymakers. Interventions should be grounded in children’s rights to a clean, healthy, and sustainable environment (United Nations General Assembly, 2022). Caregiver and household actions • Limit children’s exposure to loud toys, devices, and digital media. Discontinue or limit infants’ exposures to white noise machines. • Create quiet spaces for sleep, rest, learning, and play whenever possible. • Establish consistent, quiet bedtime routines to protect sleep quality. • Use soft materials (e.g., carpets, curtains, wall panels) to reduce ambient noise indoors. Communityand school-level solutions • Design and retrofit schools to reduce interior noise through sound-absorbing materials and better insulation. • Locate schools and childcare facilities away from major roads, airports, railways, and industrial zones. • Incorporate noise assessments into school health and safety inspections. • Advocate for community-wide quiet zones or

• Design and retrofit schools to reduce interior noise through sound-absorbing materials and better insulation. • Locate schools and childcare facilities away from major roads, airports, railways, and industrial zones. • Incorporate noise assessments into school health and safety inspections. • Advocate for community-wide quiet zones or traffic-calming measures near schools and residential areas.

Indicator definitions Lden (day-evening-night noise level) • What it means: Lden is used to measure the overall level of noise over a 24-hour period, but it gives extra weight to noise in the evening and at night because people are more sensitive to noise at these times. • Why it is used: It helps to understand how noise might affect people’s health and well-being throughout the day, including the disruptive impact of noise at night. Lnight (night-time noise level) • What it means: Lnight is used to measure the level of noise specifically at night (typically defined as 10 p.m. to 6 a.m.). Loud sounds at night can disrupt sleep and affect health. • Why it is used: It helps to assess how much night-time noise is disturbing people while they are trying to sleep, which is when they are most sensitive to noise. LAeq (average noise level) • What it means: LAeq is used to measure the average noise level over a certain period, adjusted to reflect how humans actually hear sound. Ears are less sensitive to very lowor very high-pitched sounds, so this measure ‘corrects’ for that. • Why it is used: It gives a good idea of how loud noise is over time, especially when the noise level changes (like in the case of traffic sounds or construction). It is often used to assess things like road or airport noise. Policy and regulatory framework The WHO Environmental Noise Guidelines for the European Region (World Health Organization, 2018) outline critical policy measures to protect populations (especially children) from the harmful health effects of noise pollution. While the guidelines emphasize setting exposure standards, they also highlight the importance

Policy and regulatory framework The WHO Environmental Noise Guidelines for the European Region (World Health Organization, 2018) outline critical policy measures to protect populations (especially children) from the harmful health effects of noise pollution. While the guidelines emphasize setting exposure standards, they also highlight the importance of implementing appropriate interventions and policies to achieve these standards. Establish health-based noise standards and policy measures 7The following recommendations (see also Table 1) were established based on guideline exposure levels and general and specific interventions designed to guide effective policy:

1. WHO strongly recommends keeping road traffic noise below 53 dB Lden.

2. WHO strongly recommends keeping noise levels produced by road traffic during night-time below 45 dB Lnight.

3. WHO conditionally recommends limiting the yearly average from all leisure-related noise sources combined to 70 dB L Aeq, 24 h.

It should also be noted that the indicators used are specific to the European Union and may not be directly applicable to every geographical context. Source Indicator Guideline exposure level Strength of recommendation Primary health outcomes considered Road traffic Lden ≤53 dB Strong Ischaemic heart disease, annoyance, cognitive impairment Railway traffic Lden ≤54 dB Strong Annoyance, cardiovascular effects Aircraft traffic Lden ≤45 dB Strong Annoyance, cardiovascular effects Wind turbines Lden ≤45 dB Conditional Annoyance, sleep disturbance Leisure-related noise Lden ≤70 dB Conditional Hearing impairment (from high intermittent exposures), tinnitus Road traffic Lnight ≤45 dB Strong Sleep disturbance, cardiovascular effects Railway traffic Lnight ≤44 dB Strong Sleep disturbance Aircraft traffic Lnight ≤40 dB Strong Sleep disturbance Table 1. Day-evening-night and night-time environmental noise exposure Lden: day-evening-night level (weighted average with a 5 dB penalty for evening and a 10 dB penalty for night); L night: average sound level during the night period (typically 10 p.m. to 6 a.m.); strong recommendation: guideline applies in most situations; conditional

Lden: day-evening-night level (weighted average with a 5 dB penalty for evening and a 10 dB penalty for night); L night: average sound level during the night period (typically 10 p.m. to 6 a.m.); strong recommendation: guideline applies in most situations; conditional recommendation: guideline is more context specific and may depend on local feasibility and values.

Source: Adapted from World Health Organization (2018).

8Source: Adapted from World Health Organization (2018, 2022). Specific actions to reduce noise, which can be applied to specific sources, are shown in Table 2. Noise source Specific actions to reduce noise Estimated noise reduction/impact Road traffic noise Reduce speed limits to 30 km/h in residential areas (traffic calming) 3–5 dB reduction Optimize traffic flow with synchronized signals and congestion management 2–4 dB reduction Use quieter road surfaces (e.g., porous asphalt) Up to 5 dB reduction Create buffer zones and install noise barriers near schools/playgrounds 5–15 dB reduction Promote walking, cycling and use of public transport to reduce car traffic by 10% ~1 dB community-level reduction Railway and aircraft noise Restrict night-time flights/trains (11 p.m.–7 a.m.) Up to 10 dB night noise reduction Optimize flight paths and train schedules to avoid dense residential areas 3–6 dB reduction Install noise insulation (double glazing, soundproofing) near airports and railways 20–30 dB indoor noise reduction Leisure-related noise Regulate maximum sound levels in venues (limit to <85 dB short-term exposure) Prevent hearing damage Promote safe listening practices (headphones at ≤60% volume, <1 hour of use at a time) Reduce hearing loss risk among children and adolescents WHO recommends leisure-related noise <70 dB over 24 hours Prevent long-term health effects Table 2. Actions to reduce noise that can be applied to specific sources Incorporate noise considerations into land use planning, transport policies, and building regulations and include considerations of not only urban settings,

and adolescents WHO recommends leisure-related noise <70 dB over 24 hours Prevent long-term health effects Table 2. Actions to reduce noise that can be applied to specific sources Incorporate noise considerations into land use planning, transport policies, and building regulations and include considerations of not only urban settings, but also rural settings. Measures for managing noise include the following: • designing quiet zones and green spaces around schools and hospitals; • building noise barriers and installing sound insulation; • reducing internal noise levels from, for example, fans and ventilators; • setting sound limits for concerts; • implementing traffic-calming measures; • promoting sustainable transport options. Integrate noise management into land use planning and design 9Educate communities about the health risks associated with environmental noise and involve them in noise management initiatives. Engaging stakeholders, including parents, adolescents, educators, health care professionals, and urban planners, ensures that noise reduction strategies are likely to be effective and widely supported. Implement systems to monitor environmental noise levels and assess their impact on public health. Regular evaluation helps in adapting policies and interventions to effectively mitigate noise-related health issues. Noise is a preventable environmental health hazard that undermines children’s health and key protective factors for development, including sleep, learning, and emotional well-being. Noise must be controlled at the source. Reducing excessive noise is essential not only fo