Return on the webinar of the Health-Environment Data Community: “Noise and Mental Health: Making the Invisible Visible through Data”

The environmental factors influencing health are numerous, but their understanding often remains complex. To shed light on the sometimes little-known themes of noise and mental health, Green Data for Health (CGDD/Ecolab) organized a webinar on December 11, 2024, titled: “Noise and Mental Health: Making the Invisible Visible Through Data.” This event brought together experts and researchers who highlighted the impact of noise on health and emphasized the importance and opportunities offered by data to better understand the links between environment and mental health.

This note presents the main interventions and conclusions from this webinar, covering various topics such as the extra-auditory effects of noise, the challenges posed by eco-anxiety, as well as perspectives for leveraging environmental data in favor of mental health.

I – Noise: Better Understanding the Documented, Yet Often Underestimated, Impact of Noise on Health.

Noise Pollution: Better Understanding the Proven Yet Often Underestimated Impact of Noise on Health. / Fanny Mietlicki, Director of Bruitparif.

The health risks associated with noise depend on the noise level and duration of exposure. At levels between 40 and 80 dB, extra-auditory effects such as stress or biological disruptions can occur. Between 80 and 100 dB, medium-term auditory risks increase with the duration of exposure, with a recommended limit of 85 dB over 8 hours. Beyond 100 dB, acute dangers to hearing can manifest, sometimes even with very short exposures. The extra-auditory effects of noise include discomfort, biological disorders (disruption of sleep, increase in physiological stress), impacts on cognitive and mental performance (learning, anxiety, depression), and an increase in medication consumption. In 2018, a WHO report confirmed several extra-auditory effects of noise: sleep disturbances, noise-related discomfort, ischemic heart diseases, and degradation of cognitive performance in children. Other suspected effects include impacts on the cardiovascular system, such as myocardial infarction and strokes, hypertension, effects on the metabolic system (obesity, type 2 diabetes), effects on the endocrine system (changes in the secretion of stress hormones like cortisol, catecholamines, etc.), psychological disorders (anxiety, depression), and effects on mental health.

To characterize noise levels, energy indicators, such as the L_den, a European indicator, are particularly used. These average sound fluctuations over a given period. They are obtained through modeling (based on traffic) that is validated by measurements made by fixed measurement stations or via mobile sensors. A European directive from 2022 also imposes the production of noise maps every four years in municipalities of more than 100,000 inhabitants and on major transport routes. In Île-de-France, this concerns 433 municipalities and 10.5 million inhabitants, with a precision of up to mesh sizes of 2 to 5 meters. The data collected is cross-referenced with demographic information to evaluate the population’s exposures.

This data is used to produce statistics in ecological studies, such as SOMNIBRUIT or DEBATS, or to assess individual exposure in research such as DEBATS or BROUHAHA. They also serve to quantify the health impacts of noise, for example with the quantitative health impact assessment (EQIS) conducted by Public Health France. Bruitparif carries out different types of measurements: short, medium, or long durations, fixed or mobile. The devices can detect sound levels, their spectrum, and identify sources through artificial intelligence systems.

However, energy indicators have limitations, as they sometimes mask significant variations behind averages. Bruitparif advocates for the introduction of event-based indicators to better analyze specific situations and report real exposures.

The Effects of Aircraft Noise on Health: DEBATS. / Anne-Sophie EVRARD, Research Officer in Epidemiology, Gustave Eiffel University.

The DEBATS program (Discussion on the Effects of Aircraft Noise on Health) was launched to evaluate the effects of exposure to aircraft noise on the health of residents near airports. It highlights significant effects of aircraft noise on the physical and psychological health of residents, particularly regarding sleep, discomfort, perceived health status, and effects on the cardiovascular and endocrine systems.

The first ecological study analyzes average aircraft noise exposure levels at the municipal level, estimated from noise maps, and relates them to mortality from cardiovascular diseases, ischemic heart diseases, myocardial infarctions, and strokes at the same level. The results show a increase in mortality from cardiovascular diseases in municipalities with the highest exposure to aircraft noise.

The second study is longitudinal, involving 1,244 participants at inclusion residing in one of the 161 communities close to airports. Noise exposure was estimated using noise maps, and data was collected during face-to-face interviews conducted at participants’ homes by interviewers in 2013, 2015, and 2017, using questionnaires particularly focused on participants’ health status, as well as carrying out physiological measurements. Although women report perceived poor health more frequently than men, the results reveal that an increase in exposure to aircraft noise is accompanied by a deterioration in perceived health only in men, an increase in discomfort related to aircraft noise, a modification in cortisol secretion (stress hormone), an increase in blood pressure, and a deterioration in subjective sleep quality (that is, measured by questionnaire).

Finally, a specific study on sleep involved 110 participants, for whom acoustic measurements at their homes were taken over 7 days and 7 nights, coupled with actimetric measurements that objectively characterize sleep disruptions. It demonstrated a deterioration in objective sleep quality, with a increase in heart rate amplitude in cases of high sound levels (LAmax).

Auditory Ecology, Natural Sounds, and Health. / Christian Lorenzi, Researcher at the Laboratory of Perceptual Systems, Department of Cognitive Studies at the Ecole Normale Supérieure.

Human beings are constantly exposed to varied soundscapes. These differ acoustically, but only certain sound characteristics matter to our auditory system. The latter reacts both analytically and emotionally when exposed to so-called natural soundscapes, which are those marginally affected by human activity. Emotionally, these soundscapes produce a well-established restorative effect, corresponding to a reduction in physiological stress. The biological sounds (animal vocalizations) composing these natural soundscapes are processed quickly and prioritally by our auditory system, indicating their importance for human beings.

Electrophysiological studies and neuroimaging reveal that our autonomic nervous system – specifically the parasympathetic pathway – responds specifically to these natural soundscapes, partly explaining the restorative effect. Furthermore, neuroimaging data show that biophony (the collective sound produced by the vocalizations of living organisms in a given habitat) engages specific cortical neural networks. This indicates that animal vocalizations occupy a privileged place in the processing of sounds by the human auditory brain.

Recent work on hearing-impaired patients (approximately 20% of the population in Europe) also highlights the importance of natural sounds and soundscapes in our daily activities. These studies suggest that, thanks to a conventional hearing device, the number of reports of listening to natural sounds made by hearing-impaired individuals increases by a factor of six. After fitting, patients report that these sounds are important to them, particularly those living in deep rural areas, where natural sounds play a more central role.

Behavioral studies on the auditory perception of natural sounds and soundscapes confirm this sensitivity. When subjects are asked if they hear biological sounds (animal vocalizations) within recorded natural soundscapes from various regions of the globe (forests, savanna, desert), responses vary significantly based on habitat. Recorded soundscapes in areas close to the tropics, characterized by high biodiversity, are associated with more frequent positive responses (“yes, I hear animal vocalizations”) than those recorded in regions far from the tropics. These results highlight a sensitivity to sound biodiversity in human beings.

Thus, not all environmental sounds are equivalent. The natural-origin sounds and soundscapes stand out from domestic sounds and urban soundscapes and constitute a valuable resource for human beings, both emotionally and cognitively. These sounds play an essential role in individual well-being and their relationship with their environment, underscoring the importance of valuing and preserving them.

II – Mental Health: Challenges in Harnessing Environmental Data and Perspectives.

What Links Between Environment and Mental Health? / Géraldine Molina, CNRS Researcher at ESO Nantes.

A quantitative study conducted in 2022 on 1,300 residents of Nantes explored their vulnerabilities to heatwaves and high temperatures. It is part of a broader research dynamic conducted by the ESO laboratory and IRSTV for over a decade in an interdisciplinary logic, combining natural sciences, engineering sciences, and social sciences. Based on empirical qualitative and quantitative research, an analysis model of the heat vulnerabilities of urban residents was developed, including consequences on their physical and mental health, adaptive strategies, and the refuge spaces they frequent during heatwaves.

The team of researchers led by Géraldine Molina collected and analyzed data on heatwave effects. The emphasis is placed on constructing indicators of individual and collective vulnerabilities, allowing for a better understanding of the impacts of high temperatures. In 2022, the study specifically investigated the relationship between heatwaves and urban dwellers’ adaptation strategies, highlighting the notion of refuge spaces.

The researchers also considered secondary environmental constraints, such as noise and mosquitoes. During heatwave periods, one of the preferred strategies by residents is nighttime ventilation by opening windows to cool their homes at night. Data collected in 2022 revealed that 80% of the population is concerned about high temperatures, that 40% of respondents report impacts on their physical health, and that 30% on their mental health. A third of the population found temperatures unbearable during the 2022 heatwave.

The study highlights significant inequalities in how residents experience and perceive heatwaves. Gender differences were identified: women report being more sensitive to deviations from their optimal thermal condition (greater presence at home and higher organizational burden…). Age-related inequalities also appear. The type of housing affects the ability to manage high temperatures, just as household type, for example, those living alone or in families.

This study underscores the importance of an integrated approach to understand the climatic vulnerabilities of residents and to develop tailored solutions suited to the various profiles of individuals and social groups within the same urban population. By highlighting social inequalities, it offers avenues to improve the living conditions of the most exposed populations, notably through the creation of refuge spaces and better consideration of environmental constraints.

Perspectives and Challenges in Harnessing Data. / Guillaume Chevance, Researcher at EHESP and Paquito Bernard, Researcher at Irset

Intervention by Guillaume Chevance (EHESP) :

Climate change affects mental health in two main ways: through direct impacts, such as heatwaves, and indirect impacts, notably via exposure to information about climate change. These indirect impacts contribute to the development of eco-anxiety, a phenomenon increasingly studied, though its definitions vary. Eco-anxiety may or may not be associated with functional consequences, and its environmental determinants are the subject of in-depth studies.

A longitudinal survey conducted with 750 participants over a year collected more than 6,000 observations using an application that combined questionnaire responses and GPS data. This allowed for the recreation of exposure scores based on frequented locations. This data was integrated into a model studying how eco-anxiety varies according to environmental determinants while controlling for variables such as sex, generalized anxiety level, time of day, and month.

The results show a notable association between heatwaves and eco-anxiety, with a significant increase in the latter during periods of high heat. In contrast, no clear correlation was established with air pollution or frequenting green spaces, although these aspects warrant further exploration. A prior study based on Google searches also reported spikes in interest for terms related to climate change and anxiety, suggesting a link between media exposure and eco-anxiety. Generally, frequent exposure to information about climate change correlates with an increase in eco-anxiety.

Further research is needed to deepen these links. For instance, indicator calculations have explored associations between noise and eco-anxiety, without identifying a significant link. Finally, it may be possible to couple GPS data with mental health measurements to better understand the impact of environmental determinants on eco-anxiety and propose suitable interventions.

Intervention by Paquito Bernard (Irset) :

Mental health is defined as a state of well-being in which a person can realize their potential, cope with normal life stresses, work productively, and contribute to their community. This definition underscores that there is no health without mental health, highlighting its fundamental importance. The challenges posed by climate change exert increasing pressure on mental health, particularly due to the deterioration in the quality and quantity of essential resources such as water and food.

Extreme climate events, such as wildfires, further expose young people to increased risks of psychological disorders. Floods, in turn, are associated with an increase in anxiety and depressive disorders, while heatwaves show ambivalent impacts: they may improve well-being up to a certain threshold, beyond which their effect becomes negative, leading to an increase in violence. Peaks in air pollution, on the other hand, are systematically linked to an increase in emergency psychiatric consultations, illustrating their direct impact on mental health.

Climate displacements, whether international or domestic, such as those observed in regions like Pas-de-Calais, have considerable consequences. These displacements increase the risks of depression, post-traumatic stress disorders, and hospitalization. The lifetime consequences are also concerning. For example, exposure of pregnant women to wildfires may lead to an increased risk of substance use, thus affecting the mental health of multiple generations. Finally, diagnoses of mental disorders are particularly sensitive to climate risks, underscoring the importance of considering these interactions in public health policies.

These observations reinforce the necessity for a holistic approach to integrate the impacts of environmental changes on mental health and develop strategies to protect the most vulnerable populations.

To watch the replay of the webinar, click here: https://youtu.be/HT6cFqCZNl8