Children's blood pressure and its association with road traffic noise exposure - A systematic review with meta-analysis

[Air pollution, noise and hypertension : Partners in crime]

Air pollution and traffic noise are two important environmental risk factors that endanger health in urban societies and often act together as "partners in crime". Although air pollution and noise often co-occur in urban environments, they have typically been studied separately, with numerous studies documenting consistent effects of individual exposure on blood pressure. In the following review article, we examine the epidemiology of air pollution and noise, especially regarding the cardiovascular risk factor arterial hypertension and the underlying pathophysiology. Both environmental stressors have been shown to lead to endothelial dysfunction, oxidative stress, pronounced vascular inflammation, disruption of circadian rhythms and activation of the autonomic nervous system, all of which promote the development of hypertension and cardiovascular diseases. From a societal and political perspective, there is an urgent need to point out the potential dangers of air pollution and traffic noise in the American Heart Association (AHA)/American College of Cardiology (ACC) prevention guidelines and the European Society of Cardiology (ESC) guidelines on prevention. Therefore, an essential goal for the future is to raise awareness of environmental risk factors as important and, in particular, preventable risk factors for cardiovascular diseases.

Prenatal Urban Environment and Blood Pressure Trajectories From Childhood to Early Adulthood

Background

Prenatal urban environmental exposures have been associated with blood pressure in children. The dynamic of these associations across childhood and later ages is unknown.

Objectives

The purpose of this study was to assess associations of prenatal urban environmental exposures with blood pressure trajectories from childhood to early adulthood.

Methods

Repeated measures of systolic blood pressure (SBP) and diastolic blood pressure (DBP) were collected in up to 7,454 participants from a UK birth cohort. Prenatal urban exposures (n = 43) covered measures of noise, air pollution, built environment, natural spaces, traffic, meteorology, and food environment. An exposome-wide association study approach was used. Linear spline mixed-effects models were used to model associations of each exposure with trajectories of blood pressure. Replication was sought in 4 independent European cohorts (up to 9,261).

Results

In discovery analyses, higher humidity was associated with a faster increase (mean yearly change in SBP for an interquartile range increase in humidity: 0.29 mm Hg/y, 95% CI: 0.20-0.39) and higher temperature with a slower increase (mean yearly change in SBP per interquartile range increase in temperature: -0.17 mm Hg/y, 95% CI: -0.28 to -0.07) in SBP in childhood. Higher levels of humidity and air pollution were associated with faster increase in DBP in childhood and slower increase in adolescence. There was little evidence of an association of other exposures with change in SBP or DBP. Results for humidity and temperature, but not for air pollution, were replicated in other cohorts.

Conclusions

Replicated findings suggest that higher prenatal humidity and temperature could modulate blood pressure changes across childhood.

Association of road traffic noise exposure and school childrens' cognition: A structural equation model approach

This study explores the complex relationship between traffic noise and school children's cognition, acknowledging existing empirical inconsistencies and aiming to contribute to a richer understanding of this pivotal issue. Schools adjacent to noisy roads were selected, and outdoor noise levels were measured employing a Kimo dB300 sound level meter, focusing on noise level indices LAeq, L10, and L90. Subsequent calculations were performed to determine the noise pollution level (Lnp), noise climate (NC), and traffic noise index (TNI), revealing a severe noise exposure when compared to standard guidelines. A perception questionnaire for various noise and acoustic factors influencing cognition was developed, and 1524 student responses were collected. Data analysis incorporated Principal Component Analysis (PCA) and Exploratory Factor Analysis (EFA) for dimension reduction, revealing three latent factors labelled 'annoyance,' 'behaviour,' and 'cognition'. Further, Structural Equation Modeling (SEM) was utilized to explore multivariate relationships between variables and latent factors. Resultant path coefficients were obtained as 0.12, 0.98, and 0.10 for the impact of 'behaviour' and 'annoyance' on 'cognition' and the correlation between 'annoyance' and 'behaviour', respectively. Findings underscore a potent positive impact of annoyance, stemming from acute ambient noise exposure, on the deterioration of children's cognition. While suggesting that ambient noise may be correlated with adverse health impacts due to its influence on cognition, this study emphasizes the pressing necessity for noise mitigation in roadside schools and stringent enforcement of noise pollution guidelines in academic zones.

Psychosocial and environmental risk factors of obesity and hypertension in children and adolescents-a literature overview

Childhood obesity has become a worldwide epidemic in the 21st century. Its treatment is challenging and often ineffective, among others due to complex, often not obvious causes. Awareness of the existence and meaning of psychosocial and environmental risk factors seems to be an essential element in the prevention and treatment of obesity and its complications, especially arterial hypertension. In this review, we will discuss the role of that risk factors linking obesity and increased cardiovascular disorders including the role of nutritional factors (including the role of unhealthy diet, inadequate hydration), unhealthy behaviors (e.g. smoking, alcohol and drugs, sedentary behavior, low physical activity, disrupted circadian rhythms, sleep disorders, screen exposure), unfavorable social factors (such as dysfunctional family, bullying, chronic stress, mood disorders, depression, urbanization, noise, and environmental pollution), and finally differences in cardiovascular risk in girls and boys.

Noise and Air Pollution as Risk Factors for Hypertension: Part I-Epidemiology

Traffic noise and air pollution are 2 major environmental health risk factors in urbanized societies that often occur together. Despite cooccurrence in urban settings, noise and air pollution have generally been studied independently, with many studies reporting a consistent effect on blood pressure for individual exposures. In the present reviews, we will discuss the epidemiology of air pollution and noise effects on arterial hypertension and cardiovascular disease (part I) and the underlying pathophysiology (part II). Both environmental stressors have been found to cause endothelial dysfunction, oxidative stress, vascular inflammation, circadian dysfunction, and activation of the autonomic nervous system, thereby facilitating the development of hypertension. We also discuss the effects of interventions, current gaps in knowledge, and future research tasks. From a societal and policy perspective, the health effects of both air pollution and traffic noise are observed well below the current guideline recommendations. To this end, an important goal for the future is to increase the acceptance of environmental risk factors as important modifiable cardiovascular risk factors, given their substantial impact on the burden of cardiovascular disease.

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.

Hair cortisol as a viable tool for the assessment of an association between environmental noise exposure and chronic stress

Entrenched in the well-established link between stress and health, noise exposure as a potential contributor to stress-related health effects receives tremendous attention. Indeed, exposure to noise can act as a stressor as evidenced through increased heart rate, blood pressure, adrenaline, epinephrine, and cortisol. Cortisol is secreted from the adrenal glands in response to stressor-induced activation of the hypothalamic-pituitary-adrenal axis. For assessment of environmental noise and stress, repeated sampling in blood, saliva, or urine is necessary to evaluate the association between environmental noise exposure and protracted changes in cortisol. Controlling for the many variables that influence the secretion of cortisol at discrete sampling intervals is challenging. Studies suggest that systemically produced cortisol integrates and remains in hair as it grows, providing a measure that integrates a cortisol response over a longer period, circumventing several limitations associated with multiple sampling. Robust evidence supports the integration of cortisol into hair, yet recent studies call into question the notion that cortisol is retained with growth. The current paper discusses the strengths and limitations of hair cortisol analysis with an emphasis on its utility as a measure of chronic stress in environmental noise studies.

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.

Natural and built environments and blood pressure of Alpine schoolchildren

BACKGROUND

Early life environments may influence children's blood pressure (BP), but evidence on the combined effects of natural and built environment exposures is scarce. The present study investigates the associations of natural and built environment indicators, traffic noise, and air pollution with BP in children living in Alpine valleys.

METHODS

In 2004/2005, 1251 school children (8-12 years old) were sampled for a cross-sectional survey in several Austrian and Italian mountain valleys. Children's mothers completed a questionnaire. The outcomes of interest were systolic and diastolic BP measured with a calibrated oscillometric device. Indicators of land cover assigned to the residential and school coordinates within 100 and 1000 m included normalized difference vegetation index (NDVI), tree canopy cover, and a broader naturalness indicator titled distance to nature (D2N). The presence of a home garden was also measured via self-report. Imperviousness density served as a proxy for the built environment. Residential air pollution (NO₂) and noise (L_den) from traffic were calculated using bespoke modeling. NO₂, L_den, physical activity, and body mass index (BMI) were treated as mediating pathways.

RESULTS

Higher NDVI and tree cover levels in residential and school surroundings and home gardens were consistently associated with lower BP. The built environment was associated with higher BP. Counterintuitive inverse associations between NO₂ and L_den and BP were also found. Structural equation modeling showed that higher levels of greenspace and presence of a home garden were weakly associated with more outdoor play spaces, and in turn with lower BMI, and ultimately with lower BP.

CONCLUSIONS

Exposure to natural environments may help maintain normal BP in children, while built environment may increase children's BP. Outdoor play and less adiposity in greener areas may mediate some of these associations. Evidence on air pollution and noise remains controversial and difficult to explain.

Associations of self-reported residential noise exposure with obesity and hypertension in children and adolescents

BACKGROUND

Epidemiologic evidence linking environmental noise to obesity and hypertension remains scarce, especially in children, and the results remain inconclusive. This study aims to examine the cross-sectional associations of self-reported residential noise exposure with obesity and hypertension in children and adolescents.

METHODS

As an ongoing study, a representative sample of the children aged 6-9 years in Chongqing were selected in 2014. In 2019, self-reported residential noise (answer categories: "very quiet," "moderately quiet," "slightly quiet," and "not at all quiet") data were collected, and 3,412 participants with completed data were included in the analyses.

RESULTS

Participants living in a quieter area had a significantly lower risk of obesity than those living in a noisy area (very quiet: OR = 0.50, 95%CI: 0.29-0.88, P = 0.015; moderately quiet: OR = 0.61, 95%CI: 0.36-1.02, P = 0.059). Similar associations were observed for abdominal obesity, although did not reach statistical significance. Consistently, residential noise exposure was significantly associated with body mass index (BMI) and waist-to-height ratio. Self-reported residential noise exposure was positively associated with systolic blood pressure (β = -1.808; 95%CI = -3.495, -0.110; P = 0.037). When sleep quality, study stress, BMI, and vegetable/fruits consumption were further adjusted, all effect estimates decreased, and no statistical association was observed between noise exposure and blood pressure. Furthermore, we found that the mediating effects of obesity on the associations of self-reported residential noise exposure with hypertension were 6.8% (% of total effect mediated = 0.068, 95%CI: -2.58, 3.99), although did not reach statistical significance.

CONCLUSIONS

Self-reported residential noise exposure was associated with a higher risk of obesity or abdominal obesity. Also, self-reported residential noise exposure was positively associated with hypertension, and obesity may partially mediate this association, but did not reach statistical significance.

Urban environment during early-life and blood pressure in young children

BACKGROUND

The urban environment is characterised by many exposures that may influence hypertension development from early life onwards, but there is no systematic evaluation of their impact on child blood pressure (BP).

METHODS

Systolic and diastolic blood pressure were measured in 4,279 children aged 4-5 years from a multi-centre European cohort (France, Greece, Spain, and UK). Urban environment exposures were estimated during pregnancy and childhood, including air pollution, built environment, natural spaces, traffic, noise, meteorology, and socioeconomic deprivation index. Single- and multiple-exposure linear regression models and a cluster analysis were carried out.

RESULTS

In multiple exposure models, higher child BP, in particular diastolic BP, was observed in association with higher exposure to air pollution, noise and ambient temperature during pregnancy, and with higher exposure to air pollution and higher building density during childhood (e.g., mean change [95% confidence interval] for an interquartile range increase in prenatal NO₂ = 0.7 mmHg[0.3;1.2]). Lower BP was observed in association with higher temperature and better street connectivity during childhood (e.g., temperature = -1.1[-1.6;-0.6]). Some of these associations were not robust in the sensitivity analyses. Mother-child pairs were grouped into six urban environment exposure clusters. Compared to the cluster representing the least harmful urban environment, the two clusters representing the most harmful environment (high in air pollution, traffic, noise, and low in green space) were both associated with higher diastolic BP (1.3[0.1;2.6] and 1.5[0.5;2.5]).

CONCLUSION

This first large systematic study suggests that living in a harmful urban environment may impact BP regulation in children. These findings reinforce the importance of designing cities that promote healthy environments to reduce long-term risk of hypertension and other cardiovascular diseases.

Short-Term Impact of Traffic-Related Particulate Matter and Noise Exposure on Cardiac Function

Exposure to traffic-related air pollution and noise exposure contributes to detrimental effects on cardiac function, but the underlying short-term effects related to their simultaneous personal exposure remain uncertain. The aim is to assess the impact of total inhaled dose of particulate matter and total noise exposure on the variations of electrocardiogram (ECG) parameters between pre-cycling and post-cycling periods. Mid-June 2019, we collected four participants' personal exposure data related to traffic-related noise and particulate matter (PM_2.5 and PM₁₀) as well as ECG parameters. Several Bayesian linear models were built to examine a potential association between air pollutants and noise exposure and ECG parameters: heart rate (HR), standard deviation of the normal-to-normal intervals (SDNN), percentage of successive RR intervals that differ by more than 50 ms (pNN50), root mean square of successive RR interval differences (rMSSD), low-frequency power (LF), high-frequency power (HF), and ratio of low- to high-frequency power (LF/HF). We analyzed in total 255 5-min segments of RR intervals. We observed that per 1 µg increase in cumulative inhaled dose of PM_2.5 was associated with 0.48 (95% CI: 0.22; 15.61) increase in variation of the heart rate, while one percent of total noise dose was associated with 0.49 (95% CI: 0.17; 0.83) increase in variation of heart rate between corresponding periods. Personal noise exposure was no longer significant once the PM_2.5 was introduced in the whole model, whilst coefficients of the latter that were significant previously remained unchanged. Short-term exposure to traffic-related air and noise pollution did not, however, have an impact on heart rate variability.

Green space, air pollution, traffic noise and cardiometabolic health in adolescents: The PIAMA birth cohort

BACKGROUND

Green space has been hypothesized to improve cardiometabolic health of adolescents, whereas air pollution and traffic noise may negatively impact cardiometabolic health.

OBJECTIVES

To examine the associations of green space, air pollution and traffic noise with cardiometabolic health in adolescents aged 12 and 16 years.

METHODS

Waist circumference, blood pressure, cholesterol and glycated hemoglobin (HbA1c) were measured in subsets of participants of the Dutch PIAMA birth cohort, who participated in medical examinations at ages 12 (n = 1505) and/or 16 years (n = 797). We calculated a combined cardiometabolic risk score for each participant, with a higher score indicating a higher cardiometabolic risk. We estimated exposure to green space (i.e. the average Normalized Difference Vegetation Index (NDVI) and percentages of green space in circular buffers of 300 m and 3000 m), air pollution (by land-use regression models) and traffic noise (using the Standard Model Instrumentation for Noise Assessments (STAMINA) model) at the adolescents' home addresses at the time of the medical examinations. We assessed associations of these exposures with cardiometabolic health outcomes at ages 12 and 16 by multiple linear regression, adjusting for potential confounders.

RESULTS

We did not observe consistent patterns of associations of green space, air pollution and traffic noise with the cardiometabolic risk score, blood pressure, total cholesterol levels, the total/HDL cholesterol ratio and HbA1c. We found inverse associations of air pollution with waist circumference at both age 12 and 16. These associations weakened after adjustment for region, except for particulate matter with a diameter of <2.5 μm (PM_2.5) at age 12. The association of PM_2.5 with waist circumference at age 12 remained after adjustment for green space and road traffic noise (adjusted difference - 1.42 cm [95% CI -2.50, -0.35 cm] per 1.16 μg/m³ increase in PM_2.5).

CONCLUSION

This study does not provide evidence for beneficial effects of green space or adverse effects of air pollution and traffic noise on cardiometabolic health in adolescents.

Associations between ambient air pollution and noise from road traffic with blood pressure and insulin resistance in children from Denmark

Supplemental Digital Content is available in the text.

Background:

Road traffic is a major source of air pollution and noise. Both exposures may contribute to increased blood pressure and metabolic disease; however, few studies have examined these relationships in children.

Objectives:

We aimed to investigate whether long-term exposures to air pollution and noise from road traffic were associated with increased blood pressure and insulin resistance in children.

Methods:

Cardiometabolic outcomes were derived from a follow-up examination of 629 children (10–15 years old) enrolled in the Danish National Birth Cohort. We evaluated associations with prenatal and postnatal residential exposure to nitrogen dioxide (NO₂) and noise from road traffic (L_den) using historical addresses and linear regression models.

Results:

A 10-unit increase in postnatal exposure to NO₂ and L_den was associated with a 0.31 (−0.87, 1.48) and 0.18 (−0.61, 0.96) mmHg changes in diastolic blood pressure, respectively. In contrast, both exposures were associated with decreased systolic blood pressure. After adjustment and mutual adjustment for NO₂, exposure to L_den was associated with a statistical significant decrease in systolic blood pressure both during prenatal and postnatal life, but the majority of the associations evaluated did not reach statistical significance. Inverse associations were observed for plasma fasting glucose, insulin, and HOMA of insulin resistance for both exposures, exposure windows, before and after adjustment.

Conclusions:

The findings do not support evidence of associations between long-term exposures to air pollution and road traffic noise, increased blood pressure, and a metabolic profile characteristic of increased risk for glucose intolerance or type 2 diabetes later in life.

E-noise: An increasingly relevant health risk

This article briefly reviews and discusses the current status of major non-communicable diseases (mNCDs), definition of e-noise, its possible link as a risk factor for cardiovascular diseases and other mNCDs, and proposes possible mechanisms and hypotheses on that link, and how to control e-noise in the future. E-noise is defined as signal from electronic products and instruments that emit radiation and electromagnetic fields. It includes not only the acoustic but also non-acoustic noise. Just like road traffic and aircraft noises, e-noise may not only lead to hearing loss and health problems such as fatigue, stress, irritability, headache, and insomnia, but may also endanger cardiovascular health and result in hypertension, ischemic heart disease (myocardial infarction), arrhythmia (atrial fibrillation) and stroke; brain and metabolic problems such as obesity and diabetes; mental and cognitive impairment; as well as changing of humans' long-evolved cortisol and circadian rhythms after long-term exposure. Even short-term exposure to excessive e-noise may lead to heightened stress responses and low quality of life. In conclusion, e-noise is a potential danger in our world, and further studies are needed of its effects on mechanisms of aging, disease, and human health.

Traffic noise and other determinants of blood pressure in adolescence

BACKGROUND

Exposure to traffic noise has been associated with hypertension in adults but the evidence in adolescents is limited. We investigated long-term road traffic noise exposure, maternal occupational noise during pregnancy and other factors in relation to blood pressure and prehypertension at 16 years of age.

METHODS

Systolic and diastolic blood pressure were measured in 2597 adolescents from the Swedish BAMSE birth cohort. Levels of road traffic noise were estimated at home addresses during lifetime and for the mother during pregnancy as well as maternal occupational noise exposure during pregnancy. Exposure to NO_x from local sources was also assessed. Associations between noise or NO_x exposure and blood pressure or prehypertension were analysed using linear and logistic regression.

RESULTS

The prevalence of prehypertension was higher among males and in those with overweight, low physical activity or overweight mothers. No strong or consistent associations were observed between pre- or postnatal exposure to road traffic noise and blood pressure at 16 years of age. However, inverse associations were suggested for systolic or diastolic blood pressure and prehypertension, which reached statistical significance among males (OR 0.80 per 10 dB L_den, 95% CI 0.65-0.99) and those with maternal occupational noise exposure ≥ 70 dB L_Aeq8h (OR 0.60, 95% CI 0.41-0.87). On the other hand, occupational noise exposure during pregnancy tended to increase systolic blood pressure and prehypertension risk in adolescence. No associations were seen for NO_x exposure.

CONCLUSION

No conclusive associations were observed between pre- or postnatal noise exposure and blood pressure or prehypertension in adolescents.

Residential road traffic noise as a risk factor for hypertension in adults: Systematic review and meta-analysis of analytic studies published in the period 2011-2017

Multiple cross-sectional studies indicated an association between hypertension and road traffic noise and they were recently synthetized in a WHO systematic evidence review. However, recent years have seen a growing body of high-quality, large-scale research, which is missing from the WHO review. Therefore, we aimed to close that gap by conducting an updated systematic review and meta-analysis on the exposure-response relationship between residential road traffic noise and the risk of hypertension in adults. Studies were identified by searching MEDLINE, EMBASE, the Internet, conference proceedings, reference lists, and expert archives in English, Russian, and Spanish through August 5, 2017. The risk of bias for each extracted estimate and the overall quality of evidence were evaluated using a list of predefined safeguards against bias related to different study characteristics and the Grading of Recommendations Assessment, Development and Evaluation system, respectively. The inverse variance heterogeneity (IVhet) model was used for meta-analysis. The possibility of publication bias was evaluated by funnel and Doi plots, and asymmetry in these was tested with Egger's test and the Luis Furuya-Kanamori index, respectively. Sensitivity analyses included leave-one-out meta-analysis, subgroup meta-analysis with meta-regressions, and non-linear exposure-response meta-analysis. Based on seven cohort and two case-control studies (n = 5 514 555; 14 estimates; L_den range ≈ 25-90 dB(A)), we found "low" evidence of RR _{per 10 dB(A)} = 1.018 (95% CI: 0.984, 1.053), moderate heterogeneity (I² = 46%), and no publication bias. In the subgroup of cohort studies, we found "moderate" evidence of RR _{per 10 dB(A)} = 1.018 (95% CI: 0.987, 1.049), I² = 31%, and no publication bias. In conclusion, residential road traffic noise was associated with higher risk of hypertension in adults, but the risk was lower than previously reported in the systematic review literature.

The acute effect of exposure to noise on cardiovascular parameters in young adults

Objective:

In this study, an experiment was conducted to examine whether noise exposure produced acute changes in cardiovascular responses, and whether these responses differed based on psycho-acoustic parameters to noises of low to high intensity.

Methods:

Thirty healthy subjects were enrolled. Three industrial noises were binaurally presented with a supra-aural earphone. The sound levels of noise were <55, 75, and 90 dB. Each noise was continued for 20 min and the electrocardiogram was simultaneously recorded.

Results:

The results showed a statistically significant increase in systolic blood pressure (SBP) at the 90 dB sound level. The study estimated a blood pressure increase of 0.85 mmHg/10 dB and 0.71 mmHg/10 dB in SBP and diastolic blood pressure (DBP), respectively. These results suggest that exposure to noise, particularly high-frequency noise, negatively impacts blood pressure. The tonality and fluctuation strength of noise especially impacts systolic blood pressure.

Conclusions:

The psycho-acoustic parameters of noise should be considered when evaluating the impact of noise exposure.

Global association between ambient air pollution and blood pressure: A systematic review and meta-analysis

Although numerous studies have investigated the association of ambient air pollution with hypertension and blood pressure (BP), the results were inconsistent. We performed a comprehensive systematic review and meta-analysis of these studies. Seven international and Chinese databases were searched for studies examining the associations of particulate (diameter<2.5 μm (PM_2.5), 2.5-10 μm (PM_2.5-10) or >10 μm (PM₁₀)) and gaseous (sulfur dioxide (SO₂), nitrogen dioxide (NO₂), nitrogen oxides (NO_x), ozone (O₃), carbon monoxide (CO)) air pollutants with hypertension or BP. Odds ratios (OR), regression coefficients (β) and their 95% confidence intervals were calculated to evaluate the strength of the associations. Subgroup analysis, sensitivity analysis, and meta-regression analysis were also conducted. The overall meta-analysis showed significant associations of long-term exposures to PM_2.5 with hypertension (OR = 1.05), and of PM₁₀, PM_2.5, and NO₂ with DBP (β values: 0.47-0.86 mmHg). In addition, short-term exposures to four (PM₁₀, PM_2.5, SO₂, NO₂), two (PM_2.5 and SO₂), and four air pollutants (PM₁₀, PM_2.5, SO₂, and NO₂), were significantly associated with hypertension (ORs: 1.05-1.10), SBP (β values: 0.53-0.75 mmHg) and DBP (β values: 0.15-0.64 mmHg), respectively. Stratified analyses showed a generally stronger relationship among studies of men, Asians, North Americans, and areas with higher air pollutant levels. In conclusion, our study indicates a positive association between ambient air pollution and increased BP and hypertension. Geographical and socio-demographic factors may modify the pro-hypertensive effects of air pollutants.

The Adverse Effects of Environmental Noise Exposure on Oxidative Stress and Cardiovascular Risk

Epidemiological studies have provided evidence that traffic noise exposure is linked to cardiovascular diseases such as arterial hypertension, myocardial infarction, and stroke. Noise is a nonspecific stressor that activates the autonomous nervous system and endocrine signaling. According to the noise reaction model introduced by Babisch and colleagues, chronic low levels of noise can cause so-called nonauditory effects, such as disturbances of activity, sleep, and communication, which can trigger a number of emotional responses, including annoyance and subsequent stress. Chronic stress in turn is associated with cardiovascular risk factors, comprising increased blood pressure and dyslipidemia, increased blood viscosity and blood glucose, and activation of blood clotting factors, in animal models and humans. Persistent chronic noise exposure increases the risk of cardiometabolic diseases, including arterial hypertension, coronary artery disease, diabetes mellitus type 2, and stroke. Recently, we demonstrated that aircraft noise exposure during nighttime can induce endothelial dysfunction in healthy subjects and is even more pronounced in coronary artery disease patients. Importantly, impaired endothelial function was ameliorated by acute oral treatment with the antioxidant vitamin C, suggesting that excessive production of reactive oxygen species contributes to this phenomenon. More recently, we introduced a novel animal model of aircraft noise exposure characterizing the underlying molecular mechanisms leading to noise-dependent adverse oxidative stress-related effects on the vasculature. With the present review, we want to provide an overview of epidemiological, translational clinical, and preclinical noise research addressing the nonauditory, adverse effects of noise exposure with focus on oxidative stress. Antioxid. Redox Signal. 28, 873-908.

Exploring pathways linking greenspace to health: Theoretical and methodological guidance

BACKGROUND

In a rapidly urbanizing world, many people have little contact with natural environments, which may affect health and well-being. Existing reviews generally conclude that residential greenspace is beneficial to health. However, the processes generating these benefits and how they can be best promoted remain unclear.

OBJECTIVES

During an Expert Workshop held in September 2016, the evidence linking greenspace and health was reviewed from a transdisciplinary standpoint, with a particular focus on potential underlying biopsychosocial pathways and how these can be explored and organized to support policy-relevant population health research.

DISCUSSIONS

Potential pathways linking greenspace to health are here presented in three domains, which emphasize three general functions of greenspace: reducing harm (e.g. reducing exposure to air pollution, noise and heat), restoring capacities (e.g. attention restoration and physiological stress recovery) and building capacities (e.g. encouraging physical activity and facilitating social cohesion). Interrelations between among the three domains are also noted. Among several recommendations, future studies should: use greenspace and behavioural measures that are relevant to hypothesized pathways; include assessment of presence, access and use of greenspace; use longitudinal, interventional and (quasi)experimental study designs to assess causation; and include low and middle income countries given their absence in the existing literature. Cultural, climatic, geographic and other contextual factors also need further consideration.

CONCLUSIONS

While the existing evidence affirms beneficial impacts of greenspace on health, much remains to be learned about the specific pathways and functional form of such relationships, and how these may vary by context, population groups and health outcomes. This Report provides guidance for further epidemiological research with the goal of creating new evidence upon which to develop policy recommendations.

Noise Pollution and Arterial Hypertension

Noise exposure modifies the function of multiple organs and systems. Acute noise exposure - both in laboratory settings where traffic noise is simulated and in real-life working environments - can cause increases in blood pressure, heart rate and cardiac output. This review examines the effects of noise pollution on the cardiovascular system, with a particular focus on non-auditory effects such as noise-induced arterial hypertension.