Chronic Noise Exposure and Adiposity: A Systematic Review and Meta-analysis

Environmental mixtures and body mass index in two prospective US-based cohorts of female nurses

We estimated the joint effect of particulate matter ≤ 2.5 µm in diameter (PM2.5), nitrogen dioxide (NO2), seasonal temperature, noise, greenness, light at night, and neighborhood socioeconomic status (NSES) on body mass index (BMI) in a mixture context among 194,966 participants from the Nurses' Health Study (NHS) and Nurses' Health Study II (NHSII) over 30 years. BMI was calculated from self-reported weight and height. Single- and multi-exposure generalized estimating equations models were used to estimate the difference in BMI per interquartile range (IQR) increase of environmental factors, and quantile g-computation methods were used to estimate joint associations. In both cohorts, we consistently observed positive associations of BMI with PM2.5 and NO2 concentrations as well as negative associations with light at night and NSES regardless modeling approach. A positive association with noise was only observed in NHS. Negative associations with greenness and winter temperature were only observed in NHSII. Overall, the changes in BMI per quintile increase in all eight exposures were -0.11 (-0.13, -0.08) in NHS and -0.39 (-0.41, -0.37) in NHSII, which were largely driven by air pollution and nighttime noise (18-45 %) in the positive direction and NSES (>70 %) in the negative direction. Future intervention on environmental factors, especially reducing PM2.5, NO2 and noise or improving the NSES, might be helpful to lower BMI.

Social and environmental stressors of cardiometabolic health

Exposures to social and environmental stressors arise individual behavioural response and thus indirectly affect cardiometabolic health. The aim of this study was to investigate several social and environmental stressors and the paths of their influence on cardiometabolic health. The data of 2154 participants (aged 25-64 years) from the cross-sectional population-based study were analysed. The composite score of metabolic disorders (MS score) was calculated based on 5 biomarkers: waist circumference, blood pressure, fasting blood glucose, HDL-cholesterol, triglycerides. The effects of social stressors (education level, income), environmental stressors (NO2, noise) and behavioural factors (unhealthy diet, smoking, alcohol consumption, sedentary behaviours) on MS score were assessed using a structural model. We observed a direct effect of education on MS score, as well as an indirect effect mediated via an unhealthy diet, smoking, and sedentary behaviours. We also observed a significant indirect effect of income via sedentary behaviours. The only environmental stressor predicting MS was noise, which also mediated the effect of education. In summary, the effect of social stressors on the development of cardiometabolic risk had a higher magnitude than the effect of the assessed environmental factors. Social stressors lead to an individual's unhealthy behaviour and might predispose individuals to higher levels of environmental stressors exposures.

Aircraft noise exposure and body mass index among female participants in two Nurses' Health Study prospective cohorts living around 90 airports in the United States

OBJECTIVE

Aircraft noise exposure is linked to cardiovascular disease risk. One understudied candidate pathway is obesity. This study investigates the association between aircraft noise and obesity among female participants in two prospective Nurses' Health Study (NHS and NHSII) cohorts.

METHODS

Aircraft day-night average sound levels (DNL) were estimated at participant residential addresses from modeled 1 dB (dB) noise contours above 44 dB for 90 United States (U.S.) airports in 5-year intervals 1995-2010. Biennial surveys (1994-2017) provided information on body mass index (BMI; dichotomized, categorical) and other individual characteristics. Change in BMI from age 18 (BMI18; tertiles) was also calculated. Aircraft noise exposures were dichotomized (45, 55 dB), categorized (<45, 45-54, ≥55 dB) or continuous for exposure ≥45 dB. Multivariable multinomial logistic regression using generalized estimating equations were adjusted for individual characteristics and neighborhood socioeconomic status, greenness, population density, and environmental noise. Effect modification was assessed by U.S. Census region, climate boundary, airline hub type, hearing loss, and smoking status.

RESULTS

At baseline, the 74,848 female participants averaged 50.1 years old, with 83.0%, 14.8%, and 2.2% exposed to <45, 45-54, and ≥55 dB of aircraft noise, respectively. In fully adjusted models, exposure ≥55 dB was associated with 11% higher odds (95% confidence interval [95%CI]: -1%, 24%) of BMIs ≥30.0, and 15% higher odds (95%CI: 3%, 29%) of membership in the highest tertile of BMI18 (ΔBMI 6.7 to 71.6). Less-pronounced associations were observed for the 2nd tertile of BMI18 (ΔBMI 2.9 to 6.6) and BMI 25.0-29.9 as well as exposures ≥45 versus <45 dB. There was evidence of DNL-BMI trends (ptrends ≤ 0.02). Stronger associations were observed among participants living in the West, arid climate areas, and among former smokers.

DISCUSSION

In two nationwide cohorts of female nurses, higher aircraft noise exposure was associated with higher BMI, adding evidence to an aircraft noise-obesity-disease pathway.

Traffic noise in the bedroom in association with markers of obesity: a cross-sectional study and mediation analysis of the respiratory health in Northern Europe cohort

BACKGROUND

Previous research suggests an association between road traffic noise and obesity, but current evidence is inconclusive. The aim of this study was to assess the association between nocturnal noise exposure and markers of obesity and to assess whether sleep disturbance might be a mediator in this association.

METHODS

We applied data from the Respiratory Health in Northern Europe (RHINE) cohort. We used self-measured waist circumference (WC) and body mass index (BMI) as outcome values. Noise exposure was assessed as perceived traffic noise in the bedroom and/or the bedroom window's location towards the street. We applied adjusted linear, and logistic regression models, evaluated effect modifications and conducted mediation analysis.

RESULTS

Based on fully adjusted models we found that women, who reported very high traffic noise levels in bedroom, had 1.30 (95% CI 0.24-2.37) kg/m² higher BMI and 3.30 (95% CI 0.39-6.20) cm higher WC compared to women, who reported no traffic noise in the bedroom. Women who reported higher exposure to road traffic noise had statistically significant higher odds of being overweight and have abdominal obesity with OR varying from 1.15 to 1.26 compared to women, who reported no traffic noise in the bedroom. For men, the associations were rather opposite, although mostly statistically insignificant. Furthermore, men, who reported much or very much traffic noise in the bedroom, had a statistically significantly lower risk of abdominal obesity. Sleep disturbance fully or partially mediated the association between noise in bedroom and obesity markers among women.

CONCLUSION

Our results suggest that self-reported traffic noise in the bedroom may be associated to being overweight or obese trough sleep disturbance among women, but associations were inconclusive among men.

Environmental noise-induced cardiovascular, metabolic and mental health disorders: a brief review

BACKGROUND

Environmental noise is a pervasive pollutant that is one of the greatest environmental threats to mental, physiological and psychological well-being and has a significant global health burden associated with it. Many epidemiological studies indicate long-term relationship of noise pollution with wide range of metabolic, cardio-vascular and respiratory disorders and diseases.

OBJECTIVE

The goal of this study was to thoroughly analyse available literature on public health implications and various underlying biological mechanisms associated with ambient noise exposure, taking into account both objective and subjective measures of noise exposure.

METHODS

A search of literature for review on environmental noise and associated cardiovascular, mental health and metabolic implications on human health was done using Web of Science, Google Scholar and PubMed databases.

DISCUSSION

Experimental studies indicate that noise exposure leads to endocrine effects, increased incidence of diabetes, impairment of cognitive performance, sleep disturbance and annoyance. Epidemiological evidence indicates that high levels of noise, particularly at night, may cause arterial hypertension and endothelial dysfunction due to higher level of stress hormones and oxidative stress. An increased incidence of cardio-vascular diseases like myocardial infarction, heart rate, ischemic heart disease, stroke and heart failure is associated with noise-induced mental stress. Furthermore, psychological and mental health issues like anxiety and depression are also related with exposure to noise pollution.

CONCLUSION

This article summarises a comprehensive and systematic knowledge established in recent noise research with the spotlight on cardiovascular, metabolic and mental health disorders of environmental noise, providing unique understanding into underlying mechanisms.

Impact of Noise Exposure on Risk of Developing Stress-Related Metabolic Effects: A Systematic Review and Meta-Analysis

Background

Exposure to noise can increase biological stress reactions, which may increase adverse health effects, including metabolic disorders; however, the certainty in the association between exposure to noise and metabolic outcomes has not been widely explored. The objective of this review is to evaluate the evidence between noise exposures and metabolic effects.

Materials and Methods

A systematic review of English and comparative studies available in PubMed, Cochrane Central, EMBASE, and CINAHL databases between January 1, 1980 and December 29, 2021 was performed. Risk of Bias of Nonrandomized Studies of Exposures was used to assess risk of bias of individual studies and certainty of the body of evidence for each outcome was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

Results

Fifty-six primary studies reporting on cortisol, cholesterol levels, waist circumference, glucose levels, and adrenaline and/or noradrenaline were identified. Although meta-analyses suggested that there may be an increase in waist circumference and adrenaline with increased noise exposure, the certainty in the evidence is very low. Overall, the certainty in the evidence of an effect of increased noise on all the outcomes were low to very low due to concerns with risk of bias, inconsistency across exposure sources, populations, and studies, and imprecision in the estimates of effects.

Conclusions

The certainty of the evidence of increased noise on metabolic effects was low to very low, which likely reflects the inability to compare across the totality of the evidence for each outcome. The findings from this review may be used to inform policies involving noise reduction and mitigation strategies, and to direct further research in areas that currently have limited evidence available.

Traffic noise and adiposity: a systematic review and meta-analysis of epidemiological studies

Traffic noise has attracted much attention as a significant and intractable public health threat. This study was designed as a systematical review to explore the association of traffic noise with different indicators of obesity, thus providing updated quantitative estimates for the pooled effect estimates of the existing literature. We conducted an extensive search for epidemiological studies that investigated the association of traffic noise with obesity in three electronic databases till February 23, 2021. We used random-effects meta-analysis to calculate the summary effect estimates for each 10-dB(A) increase in noise and compared the highest with the lowest category of noise in relation to seven obesity indicators. Meanwhile, we assessed the risk of bias and the overall quality of the evidence of each study as well as the level of evidence for each exposure-outcome pair. The initial search identified 30 studies, 13 of which were ultimately included. The meta-analysis for the highest versus the lowest category of noise exposure was generally associated with higher waist circumfluence (WC) ranging from 0.326 cm (95% confidence interval (CI) = 0.078, 0.574) to 0.705 cm (95% CI = 0.071, 1.340) and higher odds of central obesity ranging from 1.055 (95% CI = 1.000, 1.109) to 1.167 (95% CI = 1.037, 1.298). When the continuous exposure (each 10 dB(A) increase in noise) was introduced, similar results were found. This study indicated positive associations of traffic noise with WC and central obesity. However, in consideration of some limitations, there is an urgent need for future studies to increase the sample size, discriminate the etiological differences in different noise and obesity indicators, and thoroughly consider socioeconomic status.

Association between long-term occupational noise exposure and obesity

Noise exposure has been linked to several health outcomes including obesity. This cross-sectional study examined the association between occupational noise exposure and body mass index as a measure of general obesity in 913 textile workers (totally from nine factories) in Yazd city, Iran, from winter to summer of 2018. The sound pressure level (dBA) at each working station was measured by a calibrated sound level meter. The long-term noise exposure score of each worker (as dBA.year) was calculated by multiplying the working history in each unit to its corresponding noise level. Models were adjusted for personal, behavioral, environmental, and family history factors. In total, 81.05% (n = 740) of the participants were exposed to noise levels higher than 85 dBA. The direct association was found for the fully adjusted model (β = 0.002; 95% CI: 0.001: 0.004). For the model with past year noise exposure, a 10.6% increase in odds was observed for each 5 dBA increase in noise exposure (95% CI: 1.005: 1.216). We found a 0.1% increase in the odds of being overweight in mixed-gender analysis (95% CI: 1.001:1.002) for each 5 dBA.year in the fully adjusted model. Occupational noise exposure should be regarded as a risk factor for cardiometabolic outcomes in industrial workers.

Prenatal exposure to ambient air pollution and traffic and indicators of adiposity in early childhood: the Healthy Start study

BACKGROUND

Prenatal exposure to ambient air pollution and traffic have been related to a lower birth weight and may be associated with greater adiposity in childhood. We aimed to examine associations of maternal exposure to ambient air pollution and traffic during pregnancy with indicators of adiposity in early childhood.

METHODS

We included 738 participants of the Colorado-based Healthy Start study whose height, weight, waist circumference and/or fat mass were measured at age 4-6 years. We estimated residential exposure to ambient concentrations of fine particulate matter (PM_2.5) and ozone (O₃) averaged by trimester and throughout pregnancy via inverse distance-weighted interpolation of central site monitoring data. We assessed the distance to the nearest major roadway and traffic density in multiple buffers surrounding the participants' homes. Associations of prenatal exposure to air pollution and traffic with overweight, waist circumference, percent fat mass and fat mass index (FMI) were assessed by logistic and linear regression.

RESULTS

Associations of exposure to PM_2.5 and O₃ at the residential address during pregnancy with percent fat mass and FMI at age 4-6 years were inconsistent across trimesters. For example, second trimester PM_2.5 was associated with a higher percent fat mass (adjusted difference 0.70% [95% CI 0.05, 1.35%] per interquartile range (IQR; 1.3 µg/m³) increase), while third trimester PM_2.5 was associated with a lower percent fat mass (adjusted difference -1.17% [95% CI -1.84, -0.50%] per IQR (1.3 µg/m³) increase). Residential proximity to a highway during pregnancy was associated with higher odds of being overweight at age 4-6 years. We observed no associations of prenatal exposure to PM_2.5 and O₃ with overweight and waist circumference.

CONCLUSIONS

We found limited evidence of associations of prenatal exposure to ambient PM_2.5 and O₃ with indicators of adiposity at age 4-6 years. Suggestive relationships between residential proximity to a highway during pregnancy and greater adiposity merit further investigation.

Relationship Between Chronic Noise Exposure, Cognitive Impairment, and Degenerative Dementia: Update on the Experimental and Epidemiological Evidence and Prospects for Further Research

Degenerative dementia, of which Alzheimer's disease is the most common form, is characterized by the gradual deterioration of cognitive function. The events that trigger and promote degenerative dementia are not clear, and treatment options are limited. Experimental and epidemiological studies have revealed chronic noise exposure (CNE) as a potential risk factor for cognitive impairment and degenerative dementia. Experimental studies have indicated that long-term exposure to noise might accelerate cognitive dysfunction, amyloid-β deposition, and tau hyperphosphorylation in different brain regions such as the hippocampus and cortex. Epidemiological studies are increasingly examining the possible association between external noise exposure and dementia. In this review, we sought to construct a comprehensive summary of the relationship between CNE, cognitive dysfunction, and degenerative dementia. We also present the limitations of existing evidence as a guide regarding important prospects for future research.

Perceived built environment, health-related quality of life and health care utilization

Previous research has shown that the built environment plays a crucial role for health-related quality of life (HRQoL) and health care utilization. But, there is limited evidence on the independence of this association from lifestyle and social environment. The objective of this cross-sectional study was to investigate these associations, independent of the social environment, physical activity and body mass index (BMI). We used data from the third follow-up of the Swiss study on Air Pollution and Lung and Heart diseases In Adults (SAPALDIA), a population based cohort with associated biobank. Covariate adjusted multiple quantile and polytomous logistic regressions were performed to test associations of variables describing the perceived built environment with HRQoL and health care utilization. Higher HRQoL and less health care utilization were associated with less reported transportation noise annoyance. Higher HRQoL was also associated with greater satisfaction with the living environment and more perceived access to greenspaces. These results were independent of the social environment (living alone and social engagement) and lifestyle (physical activity level and BMI). This study provides further evidence that the built environment should be designed to integrate living and green spaces but separate living and traffic spaces in order to improve health and wellbeing and potentially save health care costs.

Impact of Sugar-Sweetened Beverage Warning Labels on Consumer Behaviors: A Systematic Review and Meta-Analysis

CONTEXT

As a primary source of added sugars, sugar-sweetened beverage consumption contributes to obesity. This study systematically synthesizes the scientific evidence regarding the impact of sugar-sweetened beverage warning labels on consumer behaviors and intentions.

EVIDENCE ACQUISITION

A keyword/reference search was performed in 2019 in Cochrane Library, PubMed, Web of Science, CINAHL, Scopus, and Google Scholar. Meta-analysis was conducted in 2020 to estimate the effect of sugar-sweetened beverage warning labels on consumers' purchase decisions.

EVIDENCE SYNTHESIS

A total of 23 studies (13 RCTs, 9 nonrandomized experiments, and 1 computer simulation study) met the eligibility criteria and were included. Labels were classified into 6 categories: (1) symbol with nutrient profile, (2) symbol with health effect, (3) text of nutrient profile, (4) text of health effect, (5) graphic with health effect, and (6) graphic with nutrient profile. Compared with the no-label control group, sugar-sweetened beverage warning label use was associated with reduced odds of choosing sugar-sweetened beverages (OR=0.49, 95% CI=0.41, 0.56) and a reduced sugar-sweetened beverage purchase intention (Cohen's d= -0.18, 95% CI= -0.31, -0.06). Across alternative label categories, the graphic with health effect (OR=0.34, 95% CI=0.08, 0.61), text of health effect (OR=0.47, 95% CI=0.39, 0.55), graphic with nutrient profile (OR=0.58, 95% CI=0.36, 0.81), and symbol with health effect (OR=0.67, 95% CI=0.39, 0.95) were associated with reduced odds of choosing sugar-sweetened beverages.

CONCLUSIONS

Sugar-sweetened beverage warning labels were effective in dissuading consumers from choosing them. Graphic with health effect labels showed the largest impact. Future studies should delineate the psychosocial pathways linking sugar-sweetened beverage warning labels to purchase decisions, recruit socioeconomically diverse participants, and design experiments in naturalistic settings.

Incidence of depression in relation to transportation noise exposure and noise annoyance in the SAPALDIA study

Prospective evidence on the risk of depression in relation to transportation noise exposure and noise annoyance is limited and mixed. We aimed to investigate the associations of long-term exposure to source-specific transportation noise and noise annoyance with incidence of depression in the SAPALDIA (Swiss cohort study on air pollution and lung and heart diseases in adults) cohort. We investigated 4,581 SAPALDIA participants without depression in the year 2001/2002. Corresponding one-year mean road, railway and aircraft day-evening-night noise (Lden) was calculated at the most exposed façade of the participants' residential floors, and transportation noise annoyance was assessed on an 11-point scale. Incident cases of depression were identified in 2010/2011, and comprised participants reporting physician diagnosis, intake of antidepressant medication or having a short form-36 mental health score < 50. We used robust Poisson regressions to estimate the mutually adjusted relative risks (RR) and 95% confidence intervals (CI) of depression, independent of traffic-related air pollution and other potential confounders. Incidence of depression was 11 cases per 1,000 person-years. In single exposure models, we observed positive but in part, statistically non-significant associations (per 10 dB) of road traffic Lden [RR: 1.06 (0.93, 1.22)] and aircraft Lden [RR: 1.19 (0.93, 1.53)], and (per 1-point difference) of noise annoyance [RR: 1.05 (1.02, 1.08)] with depression risk. In multi-exposure model, noise annoyance effect remained unchanged, with weaker effects of road traffic Lden [(RR: 1.02 (0.89, 1.17)] and aircraft Lden [(RR: 1.17 (0.90, 1.50)]. However, there were statistically significant indirect effects of road traffic Lden [(β: 0.02 (0.01, 0.03)] and aircraft Lden [β: 0.01 (0.002, 0.02)] via noise annoyance. There were no associations with railway Lden in the single and multi-exposure models [(RR_{both models}: 0.88 (0.75, 1.03)]. We made similar findings among 2,885 non-movers, where the effect modification and cumulative risks were more distinct. Noise annoyance effect in non-movers was stronger among the insufficiently active (RR: 1.09; 95%CI: 1.02, 1.17; p_interaction = 0.07) and those with daytime sleepiness [RR: 1.07 (1.02, 1.12); p_interaction = 0.008]. Cumulative risks of Lden in non-movers showed additive tendencies for the linear cumulative risk [(RR_{per 10dB of combined sources}: 1.31 (0.90, 1.91)] and the categorical cumulative risk [(RR_{triple- vs. zero-source ≥45 dB}: 2.29 (1.02, 5.14)], and remained stable to noise annoyance. Transportation noise level and noise annoyance may jointly and independently influence the risk of depression. Combined long-term exposures to noise level seems to be most detrimental, largely acting via annoyance. The moderation of noise annoyance effect by daytime sleepiness and physical activity further contribute to clarifying the involved mechanisms. More evidence is needed to confirm these findings for effective public health control of depression and noise exposure burden.

Greenspace with overweight and obesity: A systematic review and meta-analysis of epidemiological studies up to 2020

Several reviews have been conducted to assess the association between greenspace and overweight or obesity, but the conclusions were inconsistent. However, an updated comprehensive review and meta-analysis is warranted, because several high-quality papers have been published more recently. The objectives of this study are to systematically and quantitatively assess the evidence for a link between greenspace with overweight/obesity and to make specific recommendations for further research. We searched three English language databases, four Chinese language databases and the reference lists of previously published reviews for epidemiological studies on greenspace and overweight/obesity published before January 2020. We developed inclusion criteria, screened the literature and extracted key data from selected papers. We assessed methodological quality and risk of bias, and we graded the credibility of the pooled evidence. We also performed sensitivity analyses. Fifty-seven records met our inclusion criteria and were included in the study. Most studies were cross-sectional designs (81%) and were from developed nations (88%). More than half (55%) of the included studies found beneficial associations between greenspace and overweight/obesity in overall or subpopulations. Our meta-analytical results showed that greater normalized difference vegetation index was associated with lower odds of overweight/obesity in a statistically significant fashion (odds ratio [OR]: 0.88; 95% CI: 0.84, 0.91) but not residential proximity to greenspace (OR: 0.99; 95% CI: 0.99, 1.00), proportion of greenspace (OR: 0.96; 95% CI: 0.85, 1.08) or number of parks in an area (OR: 0.99; 95% CI: 0.97, 1.01). However, we detected high between-study heterogeneity in two of the four meta-analyses, which reduced the credibility of the pooled evidence. Current evidence indicates that there might be an association between greater access to greenspace and lower odds of overweight/obesity. However, additional high-quality studies are needed to more definitively assess the evidence for a causal association.

The association between road traffic noise and myocardial infarction: A systematic review and meta-analysis

This systematic review and meta-analysis study aimed to investigate the association between exposure to road traffic noise (RTN) and myocardial infarction (MI). Of 681 studies found by searching in databases, including Scopus, Web of Science, Embase, and PubMed on November 29, 2019, the number of 13 studies, including seven cohort, five case-control, and one cross-sectional studies with 1,626,910 participants and 45,713 cases of MI was included. The pooled relative risk (RR) and 95% confidence interval (CI) of MI were calculated using a random-effect model across studies. Heterogeneity measures by reporting the I-square index. Subgroup analysis according to the designs and sensitivity analysis based on the Jackknife approach was performed. We observed in the eight studies the association was investigated in different noise exposure groups and in the 10 studies (including two conference papers) the risk of MI was provided per specific unit increment of RTN. We ran two independent types of meta-analyses involving a categorical analysis (comparing the highest and the lowest category of noise exposure groups) and an exposure-response analysis (the risk of MI per 10-dB increment of RTN). The pooled RR (95% CI) of MI for the categorical and exposure-response meta-analyses was calculated 1.03 (0.93, 1.13) and 1.02 (1.00, 1.05), respectively. For both types of meta-analyses, subgroup analysis indicates a significant association in the studies with case-control and cross-sectional designs but not cohort studies. For the exposure-response meta-analysis, a significantly greater risk of MI was observed after excluding the two conference papers (RR = 1.03 and 95% CI = 1.00, 1.05) and by further excluding the studies provided originally the risk of MI only for the categorical analysis (RR = 1.02 and 95% CI = 1.01, 1.03). We did not show a significant publication bias across studies. In conclusion, our study suggests a significant odds of association between exposure to RTN and the risk of MI.

Genome-Wide DNA Methylation in Peripheral Blood and Long-Term Exposure to Source-Specific Transportation Noise and Air Pollution: The SAPALDIA Study

BACKGROUND

Few epigenome-wide association studies (EWAS) on air pollutants exist, and none have been done on transportation noise exposures, which also contribute to environmental burden of disease.

OBJECTIVE

We performed mutually independent EWAS on transportation noise and air pollution exposures.

METHODS

We used data from two time points of the Swiss Cohort Study on Air Pollution and Lung and Heart Diseases in Adults (SAPALDIA) from 1,389 participants contributing 2,542 observations. We applied multiexposure linear mixed-effects regressions with participant-level random intercept to identify significant Cytosine-phosphate-Guanine (CpG) sites and differentially methylated regions (DMRs) in relation to 1-y average aircraft, railway, and road traffic day-evening-night noise (Lden); nitrogen dioxide (NO 2 ); and particulate matter (PM) with aerodynamic diameter < 2.5 μ m (PM 2.5 ). We performed candidate (CpG-based; cross-systemic phenotypes, combined into "allostatic load") and agnostic (DMR-based) pathway enrichment tests, and replicated previously reported air pollution EWAS signals.

RESULTS

We found no statistically significant CpGs at false discovery rate < 0.05 . However, 14, 48, 183, 8, and 71 DMRs independently associated with aircraft, railway, and road traffic Lden; NO 2 ; and PM 2.5 , respectively, with minimally overlapping signals. Transportation Lden and air pollutants tendentially associated with decreased and increased methylation, respectively. We observed significant enrichment of candidate DNA methylation related to C-reactive protein and body mass index (aircraft, road traffic Lden, and PM 2.5 ), renal function and "allostatic load" (all exposures). Agnostic functional networks related to cellular immunity, gene expression, cell growth/proliferation, cardiovascular, auditory, embryonic, and neurological systems development were enriched. We replicated increased methylation in cg08500171 (NO 2 ) and decreased methylation in cg17629796 (PM 2.5 ).

CONCLUSIONS

Mutually independent DNA methylation was associated with source-specific transportation noise and air pollution exposures, with distinct and shared enrichments for pathways related to inflammation, cellular development, and immune responses. These findings contribute in clarifying the pathways linking these exposures and age-related diseases but need further confirmation in the context of mediation analyses. https://doi.org/10.1289/EHP6174.

Associations of residential greenness, traffic noise, and air pollution with birth outcomes across Alpine areas

Aim This explorative study aimed to investigate the association of residential greenness, traffic noise, and air pollution with birth outcomes in several Alpine areas with unique topography.

METHODS

We used data from two cross-sectional studies (UIT, n = 573 and BBT, n = 518) in the Tyrol Region (Austria/Italy). Only mothers who had lived in their current residence during the whole pregnancy were included. They completed a questionnaire, and medical records were used to draw data on birth weight, low birth weight (LBW), preterm birth, and small for gestational age (SGA). Normalized Difference Vegetation Index (NDVI) in the year of birth was assigned at the residential address as a measure of greenness. Road/railway traffic noise (L_dn) and air pollution (NO₂) were calculated about 10 years after birth and used as surrogates for exposure levels during pregnancy.

RESULTS

In the UIT survey, higher NDVI_500-m was consistently associated with lower odds for LBW and SGA, while an increase of L_dn was associated with higher odds for LBW. Other effect estimates were in the expected direction albeit non-significant. In the BBT survey, most findings were inconclusive (for NDVI) or present only in subgroups (for L_dn and NO₂).

CONCLUSION

This study provides inconclusive evidence that the surrounding environment might be associated with birth outcomes in mountainous areas. Given the disparate associations across the study areas, further research in larger representative samples is warranted.

Sounds of Nature in the City: No Evidence of Bird Song Improving Stress Recovery

Noise from city traffic is one of the most significant environmental stressors. Natural soundscapes, such as bird songs, have been suggested to potentially mitigate or mask noise. All previous studies on masking noise use self-evaluation data rather than physiological data. In this study, while respondents (n = 117) watched a 360° virtual reality (VR) photograph of a park, they were exposed to different soundscapes and mild electrical shocks. The soundscapes—“bird song”, “bird song and traffic noise”, and “traffic noise”—were played during a 10 min recovery period while their skin conductance levels were assessed as a measure of arousal/stress. No significant difference in stress recovery was found between the soundscapes although a tendency for less stress in “bird song” and more stress in “traffic noise” was noted. All three soundscapes, however, significantly reduced stress. This result could be attributed to the stress-reducing effect of the visual VR environment, to the noise levels being higher than 47 dBA (a level known to make masking ineffective), or to the respondents finding bird songs stressful. Reduction of stress in cities using masking with natural sounds requires further studies with not only larger samples but also sufficient methods to detect potential sex differences.