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Blood pressure of 8–14 year old children in relation to traffic noise at home — Results of the German Environmental Survey for Children (GerES IV)
Science of the Total Environment 407 (2009) 5839–5843
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Science of the Total Environment j o u r n a l h o m e p a g e : w w w. e l s ev i e r. c o m / l o c a t e / s c i t o t e n v
Blood pressure of 8–14 year old children in relation to traffic noise at home — Results of the German Environmental Survey for Children (GerES IV) Wolfgang Babisch a,⁎, Hannelore Neuhauser b,1, Michael Thamm b,2, Margarete Seiwert a,3 a b
Federal Environment Agency, Department of Environmental Hygiene, Corrensplatz 1, 14195 Berlin, Germany Robert Koch Institute, Department of Epidemiology and Health Reporting, General-Pape-Str. 62-66, 12101 Berlin, Germany
a r t i c l e
i n f o
Article history: Received 29 May 2009 Received in revised form 21 July 2009 Accepted 7 August 2009 Available online 2 September 2009
a b s t r a c t Objectives: The German Environment Agency carried out its fourth German Environmental Survey (GerES IV) from 2003 to 2006, which was especially for children. 1048 children, 8–14 years of age, were randomly selected from all over Germany. The sample is representative of children in this age group living in Germany with respect to gender, community size, and region. Methods: Blood pressure was measured under standardized conditions at clinical study centers. During home visits the children and their parents were asked about leisure activities, housing conditions and environmental factors, including traffic exposure of their homes. Orientating short-term noise measurements were carried out in front of the children's (bed-) room to validate the subjective ratings of the traffic volume (categories: no street, low, moderately, high/extremely high). Results: With respect to the subjective rating of “type of street” (traffic volume) the lowest blood pressure readings were found in children whose room was facing a street with ‘low traffic’. The highest readings were found in the group where the children's rooms were facing a street with a ‘high or extremely high traffic’ volume. The difference between the two groups was 1.8 mm Hg (95% CI: 0.1 to 3.5, p = 0.036) for systolic and 1.0 mm Hg (95% CI: − 0.4 to 2.4, p = 0.148) for diastolic blood pressure. With respect to the short-term noise measurements, significant blood pressure increases of 1.0 mm Hg (95% CI: 0.3 to 1.6, p = 0.004) and 0.6 mm Hg (95% CI: 0.1 to 1.2, p = 0.025), respectively, were found per 10 dB(A) increment of the noise level. Conclusions: The results show that road traffic noise at home is a stressor that could affect children's blood pressure. © 2009 Elsevier B.V. All rights reserved.
1. Introduction Noise affects children in many ways. Exposure to transport noise can lead to annoyance, stress responses, cognitive impairment and possibly cardiovascular problems (Zuurbier et al., 2007). Noise effects in children may be different from those in adults because the timeactivity patterns of children differ from those of adults (Bistrup et al., 2006). Adults and children are exposed to the same environmental noises while sleeping at night. However, children go to bed earlier and sleep longer — and thus may be exposed to daytime noise during sleep. Especially very young children cannot determine their acoustic environment. They have less control over their environment than adults.
⁎ Corresponding author. Tel.: +49 30 8903 1370; fax: +49 30 8903 1830. E-mail addresses: [email protected] (W. Babisch), [email protected] (H. Neuhauser), [email protected] (M. Thamm), [email protected] (M. Seiwert). 1 Tel.: +49 30 18754 3462; fax: +49 30 18754 3555. 2 Tel.: +49 30 18754 3204; fax: +49 30 18754 3211. 3 Tel.: +49 30 8903 1370; fax: +49 30 8903 1311. 0048-9697/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.scitotenv.2009.08.016
Effects of noise on children's blood pressure have been investigated with respect to road traffic noise and aircraft noise (Babisch, 2006). The results were contradictory. Aircraft noise was mostly assessed at schools. However, since the children normally lived within the vicinity of the schools, the noise assessment also reflected the exposure at home. Higher systolic and/or diastolic blood pressure readings in higher noise-exposed subjects were primarily found in children exposed to aircraft noise in the Los Angeles studies (Cohen et al., 1980; Cohen et al., 1981), the Munich studies (Evans et al., 1995), and in the Dutch sub-sample of the RANCH studies carried out around Amsterdam airport (van Kempen et al., 2006). However, nilresults were found in the UK sample of the RANCH study (van Kempen et al., 2006) and the Sydney studies (Morrell et al., 1998, 2000). With respect to road traffic noise, only in the study carried out in Bratislava were higher blood pressure readings found in children exposed to road traffic noise at home and at day care centers (Regecová and Kellerová, 1995). Nil-results were found in the UK sample of the RANCH study (van Kempen et al., 2006) and the Tyrol studies (Evans et al., 2001; Lercher, 1992); negative findings were found in the Dutch sample of the RANCH study (van Kempen et al., 2006). The differences of mean blood pressure readings between
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‘exposed’ and ‘non-exposed’ children, if any, were very slight (1 to 5 mm Hg), depending on the noise level contrast. As being part of a nation-wide environment and health survey the blood pressure and the exposure to noise from road traffic were assessed in a representative sample of children in Germany. 2. Methods The noise annoyance of 8–14 year old children was assessed in a random population sample within the framework of the “German Environmental Survey for Children (GerES IV)”. The survey was carried out from 2003 to 2006 by the German Federal Environment Agency. The participants were a sub-sample of the “Health Interview and Examination Survey for Children and Adolescents (KiGGS)”, which was carried out by the Robert Koch Institute (Kurth et al., 2008). Details of the sampling procedure and the study design are given elsewhere (Babisch, 2009; Becker et al., 2005; Schulz et al., 2008). The sampling procedure of this cross-sectional KiGGS survey was based on a two-stage protocol. First, a systematic sample of primary sample units (KiGGS: 167, GerES IV:150) was drawn from an inventory of German communities stratified by the grade of urbanization and the geographical distribution. At the second stage, an equal number of addresses per birth cohort were randomly selected from local population registers within the primary sample units. In a third step the GerES IV sample was drawn, which included 1790 3–14 year old children that were randomly selected from the pool of subjects (parents) that had given their consent for participation in the survey. The total response rate (KiGGS + GerES IV) was 52.6%. The GerES IV sample is representative of children in this age group living in Germany with respect to gender, community size, and region. According to the noise assessment protocol of the survey, all noise-related analyses refer to the sub-sample of 8–14 year old children (N = 1048), who also additionally had a hearing test. The statistical analyses were carried out using the statistical software package SPSS15. Depending on the scale-level Chi2-, Gamma-, and Mann–Whiney-Tests were carried out to assess associations. Multiple variance analyses to control for covariates were carried out using the procedure UNIANOVA. The parents were asked to classify the type of street on which their dwelling was located (categories: ‘low traffic side street’, ‘moderate traffic side street’, ‘heavy traffic side street’, ‘busy main road or major trunk road’). In the case of more than one relevant street, answers were to be given with respect to the busiest street. The parents were also asked whether the child's room was facing this street. Furthermore, during the home visit the parents rated the traffic volume of the street to which the children's room windows were facing (question: “Is there a street right in front of the children's bedroom window — yes/no? If yes, how would you characterize the traffic volume of this street — low/moderate/busy/extremely busy?” For statistical analyses these two answers were combined to the categories: ‘no street’, ‘low traffic street’, ‘moderate traffic street’, ‘busy street’, ‘extremely busy street’). For validation, the interviewers rated the traffic volume of the street using the same scale in a separate questionnaire. The ratings were very similar (Gamma-coefficient = 0.993, p < 0.000). In the following analyses the parent's ratings were used, because they were based on much longer experience of the traffic conditions, including the night. During the home visit an approx. 15 min integrating orientating noise measurement was taken in front of the child's open room window (sound level meter NORSONIC Type 116); LASm, LASmax, and LApeak were recorded. The measurements were carried out between 8:00 and 21:30, depending on the time of the visit (mean 15:22, standard deviation: 2:21). Across 10 areal agglomeration levels (range: ≤ 2000–≥ 500,000 inhabitants) no distributional differences of the time of the measurements were found. Considering the fact that variations greater than ± 3 dB(A) (double/half of the traffic volume) are
very unlikely to happen throughout the daytime — particularly on busy roads, no weighting of noise levels depending on the time of the day was applied. The crude noise measurements were considered as reasonable additional information for epidemiological purposes on a group level and for validation of the subjective scales regarding type of street and traffic volume. Other permanent noise sources than road traffic that might have been the primary sources were documented by the interviewer (e. g. railway: 0.5%, aircraft: 1.4%, industry: 0.6%, construction: 2.1%, neighborhood: 19.5%, natural sounds 25.1% of the measurements). High peak noise levels may be an indicator for confounding noise sources. Both kinds of information were used for sensitivity analyses. Annoyance of the children from road traffic noise was assessed by questionnaire during home visits (face to face interview). A dichotomous annoyance scale (‘yes/no’) was applied to the 8–10 year old children (n = 448), and a numerical 5-point scale (‘not at all/ slightly/moderately/very/extremely’) was applied to the 11–14 year old children (n = 600) in the style of the German version (FelscherSuhr et al., 2000) of the recommendations for the assessment of annoyance in community noise studies (Fields et al., 2001). A distinction was made between the annoyance during the day and the night. The medical data of all the children were assessed at ad-hoc clinics that where set up in the study areas. Resting blood pressure measurements were carried out twice at a two minute interval under standardized conditions using an automatic device (Datascope Accutorr Plus). The measurement was carried out after 5-minute rest in the sitting position (right arm). Details are given elsewhere (Neuhauser and Thamm, 2007).Oscillometric systolic and diastolic blood pressure and heart rate were measured. The average of the two measurements was used for further analyses. Height and weight of the children were considered in the analyses as covariates to control for confounding. Both show a largely steady trend with blood pressure in children (Michels et al., 1998; Neuhauser and Thamm, 2007). Physical activity was assessed differently in the 8–10 and the 11– 14 year old children. The parents of the younger children were asked how frequent their children played outdoors and carried out sports. The older children answered themselves with respect to the frequency and the duration of heavy exercises in their leisure time. Stratified analyses were carried out within each age group to assess the impact of the inclusion of these variables on the association between road traffic noise and blood pressure. An indicator variable was created that was used in the total sample for control of confounding (8–10 year old children: ‘physical active’ = playing outdoors nearly every day or carrying out sports at least once per week, ‘physical inactive’ = others; 11–14 year old children: ‘physical active’ = heavy exercise at least once a week, ‘physical inactive’ = others). All descriptive analyses were stratified according to a set of sociodemographic variables, including age (8–10, 11–12, 13–14 years), gender (boys, girls), area (eastern, western Germany), socio-economic status (low, medium, high — based on ‘Winkler’ index (Kurth et al., 2008)), migrant status (German, non-German citizenship), and agglomeration size (<100,000, ≥100,000). Individual data regarding the exposure to (outdoor) air pollutants were not available (random sample from all over Germany). However, although air pollution was found to be associated with myocardial infarction and mortality, there is not much evidence that it is associated with high blood pressure, particularly in children (European Respiratory Society, 2006; Jarup et al., 2007; The PEP, 2009). 3. Results 16.5% of the children lived in dwellings on a ‘busy main road or a major trunk road’, 11.7% on a ‘heavy traffic side street’, 31.1% on a ‘moderate traffic side street’, and 40.6% on a ‘low traffic side street’.
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The proportion of children with a room with windows facing the street increased (Chi2-Trend-Test: p < 0.001) with increasing noise exposure across the four street categories from 45% (‘low traffic side street’) to 61% (‘busy main road or major trunk road’). Nearly half of the children's rooms (47.7%) had windows not facing a street. Table 1 shows the distribution of children over the type of street categories, referring to the street in front of the children's room. 13.9% of the children's room windows were facing a ‘busy traffic street’ or an ‘extremely busy traffic street’. The 15-minute average noise levels which were measured in front of the children's room showed a symmetric distribution, ranging from 27 to 86 dB(A) (mean: 50, standard deviation: 7). Maximum noise levels (“slow”) ranged between 36 and 94 dB(A), peak noise levels between 39 and 115 dB(A). Non-parametric correlation coefficients between the ordinary scale of traffic volume in front of the children's room and the noise levels were: 0.56 (LASm: rs = 0.56, LAmax: rs = 0.37, LApeak: rs = 0.18), indicating that the verbal graduates of the traffic volume correlate well with the short-term average noise level. Table 1 and Fig. 1 show the mean noise levels (LASm) and 95 percent confidence intervals for different subjective type of street categories. Table 2 shows the distribution of children over the annoyance categories regarding the annoyance due to road traffic noise during the day and the night. The results of the 8–10 and 11–14 year old children are shown separately, because different annoyance scales were used for the 8–10 and 11–14 year old children. Blood pressure and heart rate showed a largely symmetric distribution. Only the systolic blood pressure was slightly skewed due to a few high readings. Table 3 shows the mean blood pressure reading, including 95% confidence intervals, of the children for each type of street category. The results are model-adjusted (UNIANOVA) with respect to age, gender, area, socio-economic status, migrant status, agglomeration size, height, weight and physical activity. Higher blood pressure readings are found in children exposed to noise from busy streets. When the upper two exposure categories are taken together (‘busy traffic street’ and ‘extremely busy traffic street’) and ‘low traffic street’ is taken as the reference category (statistical test of contrast), the difference between the two extreme groups is 1.8 mm Hg (95% CI: 0.1 to 3.5, p = 0.036) for systolic and 1.0 mm Hg (95% CI: − 0.4 to 2.4, p = 0.148) for diastolic blood pressure. The effect on systolic blood pressure is statistically significant. When ‘no street’ is considered as the reference category, the respective differences are 1.2 mm Hg (95% CI: − 0.3 to 2.6, p = 0.126) and 0.5 mm Hg (95% CI: − 0.7 to 1.7, p = 0.441). Stratified analyses using the complete information regarding the physical activity of the 8–10 and 11–14 year old children (which was differently assessed) did not reveal a notable impact of physical activity on the associations between noise and blood pressure in these subgroups. With respect to the short-term noise measurements, multiple linear regression analyses – adjusted for the full set of covariates – revealed significant blood pressure increases of 0.96 mm Hg (95% CI: 0.30 to 1.62, p = 0.004) for systolic and 0.61 mm Hg (95% CI: 0.08 to 1.15, p = 0.025) for diastolic blood pressure per 10 dB(A) increment of the sound level. Fig. 2 shows the scatterplot of the crude unadjusted association between the noise level and the systolic blood pressure
Table 1 Distribution of children and measured short-term noise levels over type of street categories. Street category
Percentage of children
Noise level LASm [dB(A)] Mean (95% confidence interval)
‘No street’ ‘Low traffic street’ ‘Moderate traffic street’ ‘Busy traffic street’ ‘Extremely busy traffic street’
47.7% 20.7% 17.7% 11.1% 2.8%
48 (47–49) 48 (47–49) 52 (51–53) 58 (57–59) 60 (58–63)
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Fig. 1. Association between type of street categories and noise level.
(1.39 mm Hg per 10 dB(A) (95% CI: 0.59 to 2.2, p = 0.001)). No noise effects were found with respect to heart rate. It should be noted that no significant differences were found between the time of the noise measurement and the type of street (‘no street’: mean = 15:17, SD = 2:22; ‘low traffic street’: mean = 15:30, SD = 2.19; ‘moderate traffic street’: mean = 15:15, SD = 2:16; ‘busy traffic street’: mean = 15:35, SD = 2:23; ‘extremely busy street’: mean = 15:19, SD = 2:41). Sensitivity analyses – excluding subjects where the peak noise level exceeded 101 dB(A) (5 percent percentile) or where anthropogenic sound sources were prevalent during the home visit outside the children's room – did not change the results considerably (slightly larger effect estimates were found). When the objective noise indicators were replaced by the subjective indicators of road noise perception (annoyance) a tendency to higher blood pressure readings was found in the group of 8–10 year old children who were annoyed during the day or during the night by road traffic noise. The results from this group as shown in Table 4, however, were not statistically significant. Table 5 shows the results of the group of 11–14 year olds. Subjects that were ‘slightly’, ‘moderately’, ‘very’ or ‘extremely’ annoyed = ‘little’ annoyed were taken together due to small numbers (low annoyance of the children, see Table 2). A tendency towards lower blood pressure readings was found in those children who were annoyed during the night by road traffic noise, which was found to be significant (p = 0.012) for diastolic blood pressure. 4. Discussion The association between road traffic noise and blood pressure was investigated in 1048 children, 8–14 year of age. The children Table 2 Distribution of children over road traffic noise annoyance categories. Annoyance rating
8–10 year old children
11–14 year old children
Day
Night
Day
Night
‘No’ ‘Yes’ ‘Not at all’ ‘Slightly’ ‘Moderately’ ‘Very’ ‘Extremely’
92.8% 7.2%
93.3 6.7 81.7 14.3 3.2 0.7 0.1
91.8 5.4 2.2 0.5 0.1
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Table 3 Mean (95% confidence intervals) systolic and diastolic blood pressure readings of 8–10 year old children by type of street categories. Street category
Systolic blood pressurea [mm Hg]
Diastolic blood pressurea [mm Hg]
‘No street’ ‘Low traffic street’ ‘Moderate traffic street’ ‘Busy traffic street’ ‘Extremely busy traffic street’
108.7 108.0 108.5 109.8 109.9
65.3 64.8 65.1 65.9 65.6
(107.5–109.8) (106.5–109.5) (107.1–109.9) (108.1–111.5) (106.8–112.9)
(64.4–66.3) (63.6–66.0) (64.0–66.3) (64.5–67.3) (63.1–68.1)
Table 4 Mean (95% confidence intervals) systolic and diastolic blood pressure readings of 8–10 year old children by road traffic noise annoyance. Annoyance rating 8–10 year old children (2 point scale) Day Night
‘No’ ‘Yes’ ‘No’ ‘Yes’
Systolic blood pressurea [mm Hg]
Diastolic blood pressurea [mm Hg]
104.9 105.4 103.0 105.0
63.9 65.5 63.2 64.1
(103.2–106.5) (102.4–108.4) ( 99.8–106.2) (103.4–106.7)
(62.6–65.2) (63.1–67.9) (60.7–65.8) (62.8–65.4)
a Adjusted for age, gender, area, socio-economic status, migrant status, agglomeration size, height, weight and physical activity.
a Adjusted for age, gender, area, socio-economic status, migrant status, agglomeration size, height, weight and physical activity.
participated in the German Environmental Survey for Children (GerES IV) which consists of a sub-sample of the representative German Health Interview and Examination Survey for Children and Adolescents (KiGGS). The exposure to road traffic noise was determined by the parent's classification of the type of road in front of the children's room, and by orientating short-term noise measurements carried out during the day in front of the children's room window. While the noise questionnaire and the noise measurements were applied at home, the blood pressure measurements were carried in ad-hoc medical clinics. The resting blood pressure measurement, in this respect, reflects a chronic state of the children's circulatory system, which was not affected by the acute noise situation at home. Small, but higher systolic and diastolic blood pressure readings were found in children who were exposed to noise from busy streets compared with less exposed children when the type of street was considered as the factor of exposure. The lowest blood pressure readings were found in children whose room was facing a street with ‘low traffic’ volume. The highest readings were found in the group where the children's rooms were facing a street with a ‘high or extremely high traffic’ volume. The mean difference between the two groups was 1.8 mm Hg for systolic and 1.0 mm Hg for diastolic blood pressure. The effect was significant only for systolic blood pressure due to statistical power (sample size). However, it appears also reasonable to assume that manifest arteriosclerotic manifestations of increased blood pressure were not present in those young children. The effect may rather be due to sympathetic arousal, which is more pronounced in systolic blood pressure. The results confirm the findings of a few other studies where slightly higher blood pressure readings were found in children exposed
to high noise level, either at home or at school/day care centers (Karsdorf and Klappach, 1968; Regecová and Kellerová, 1995). However, negative or nil results were also found in studies (Evans et al., 2001; van Kempen et al., 2006; Lercher, 1992). ‘J-shaped’ associations were found when the presumably quietest category (‘no street’) was considered as a reference group. This group had a slightly higher systolic and diastolic blood pressure on average – 0.6 and 0.5 mm Hg, respectively – than the ‘low traffic’ group. This may be due to road traffic in the distance when there was no street right in front of the children's bedroom. Although the 15-minute short-term noise measurements did not reveal a difference in the average equivalent sound pressure level between those groups, children from the ‘no street’ group were slightly more annoyed by road traffic noise than the ‘low traffic’ group (not shown). Different time patterns of the acoustical signals (very few noise events close to the room (‘low traffic’) versus continuous noise from the distance (‘no street’)) might be an explanation for this finding. However, when the noise level was considered as the factor of exposure, significant linear trends of an increase of both, systolic (1.0 mm Hg per 10 dB(A)) and diastolic blood pressure (0.6 mm Hg per 10 dB(A)), with increasing noise levels were found. With respect to annoyance due to road traffic noise, a non-significant tendency to higher blood pressure readings was found in the group of younger children (8–10 years) who were annoyed by noise. In the older children (11–14 years) the opposite was found, which was significant for the association between night-time noise annoyance and diastolic blood pressure. This contradictory finding is difficult to explain. Possibly the older children who had expressed their annoyance had better and more effective ways of coping with the noise (Lercher, 1996). However, the finding could be accidental due to the small numbers of annoyed children. The results were adjusted for potentially confounding factors, including age, gender, area, socio-economic status, migrant status, agglomeration size, height, weight and physical activity. With regard to possible health risks in their later life, the findings in children are difficult to interpret. The effect may be of a temporary nature and may
Table 5 Mean (95% confidence intervals) systolic and diastolic blood pressure readings of 11–14 year old children by road traffic noise annoyance. Annoyance rating 11–14 year old children (5 point scale) Day
Night
Fig. 2. Scatterplot of the association between noise level and systolic blood pressure.
‘Not at all’ ‘Slightly’, ‘moderately’,‘very’ or ‘extremely’ ‘Not at all’ ‘Slightly’, ‘moderately’,‘very’ or ‘extremely’
Systolic blood pressurea [mm Hg]
Diastolic blood pressurea [mm Hg]
111.4 (110.0–112.9) 112.4 (110.5–114.4)
66.4 (65.2–67.6) 66.0 (64.4–67.6)
111.8 (110.4–113.2) 110.1 (107.6–112.7)
66.5 (65.4–67.7) 64.2 (62.1–66.3)
a Adjusted for age, gender, area, socio-economic status, migrant status, agglomeration size, height, weight and physical activity.
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not be relevant to permanent health damage. On the other hand, there is evidence that during childhood (Gillman et al., 1992), adolescence (Yong et al., 1993) and adulthood (Tate et al., 1995) the blood pressure level at an early age is an important predictor of the blood pressure level at a later age. A crude hint regarding reversible effects on blood pressure came from the Sydney study (Morrell et al., 2000). It was concluded that children do not seem to adapt to high levels of road traffic noise but to some extent to aircraft noise (Bistrup et al., 2001; Passchier-Vermeer, 2000). However, the data base appears to be too poor to draw final conclusions. Aircraft noise studies focussed on the exposure at school, while road traffic noise studies mostly considered the noise exposure at home. Different mechanisms (disturbed learning/concentration vs. disturbed relaxation/sleep) may be involved. The conclusions given by Evans and Lepore still seem to hold some truth (Evans and Lepore, 1993): “We know essentially nothing about the long-term consequences of early noise exposure on developing cardiovascular systems. The degree of blood pressure elevations is small. The clinical significance of such changes in childhood blood pressure is difficult to determine. The ranges of blood pressure among noise-exposed children are within the normal levels and do not suggest hypertension. The extent of blood pressure elevations found from chronic exposure are probably not significant for children during their youth, but could portend elevations later in life that might be health damaging.” 5. Conclusions The results of the German Environmental Survey for Children (GerES IV) give some indication that children who are exposed to high levels of road traffic noise may have higher blood pressure. The longterm consequences of those small noise-related blood pressure elevations for children's health remain unclear. Acknowledgments The German Environmental Survey for Children (GerES IV) was funded by the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety, and the Federal Ministry of Education and Research. The authors are indebted to all children who participated in this study, and to their parents. The complex study could not have been realized without the strong commitment of the study team and so many more colleagues in the Robert Koch Institute and the Federal Environment Agency. Disclaimer: Statements and opinions expressed in this article are those of the authors. References Babisch W. Transportation noise and cardiovascular risk: updated review and synthesis of epidemiological studies indicate that the evidence has increased. Noise Health 2006;8(30):1-29. Babisch W. Kinder-Umwelt-Survey (KUS) 2003/06 Lärm. Daten und Materialiensammlung, Deskription und Zusammenhangsanalysen. Umwelt & Gesundheit 01/2009. Umweltbundesamt, Dessau-Roßlau / Bad Elster / Berlin, 2009. Becker K, Schulz C, Babisch W, Dürkop J, Rosskamp E, Seiwert M, et al. German environmental survey for children (GerES IV) 2003–2006. Pollut Atmos 2005;188: 475–9. Bistrup ML, Hygge S, Keiding L, Passchier-Vermeer W. Health effects of noise on children — and perception of risk of noise. Copenhagen: National Institute of Public Health; 2001.
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Blutdruckmessung im Kinder- und Jugendgesundheitssurvey (KiGGS). Bundesgesundheitsbl-Gesundheitsforsch-Gesundheitsschutz 2007;50: 728–35. Passchier-Vermeer W. Noise and health of children. TNO report PG/VGZ/2000.042. Leiden: Netherlands Organization for Applied Scientific Research (TNO; 2000. Regecová V, Kellerová E. Effects of urban noise pollution on blood pressure and heart rate in preschool children. J Hypertens 1995;13:405–12. Schulz C, Seiwert M, Becker K, Conrad A, Kolossa-Gehring M. Der Kinder-UmweltSurvey 2003–2006 (KUS): Stichprobe und Studienbeschreibung. Umweltmed Forsch Prax 2008;13:379–90. Tate RB, Manfreda J, Krahn AD, Cuddy TE. Tracking of blood pressure over a 40-year period in the University of Manitoba follow-up study, 1948–1988. Am J Epidemiol 1995;142:946–54. The PEP. Transport, Health and Environment, Pan European Programme. Economic valuation of transport-related health effects: review of methods and development of practical approaches, with a special focus on children. Copenhagen: WHO Regional Office for Europe; 2009. Yong L-C, Kuller LH, Rutan G, Bunker C. Longitudinal study of blood pressure: changes and determinants from adolescence to middle age. The Dormont High School follow-up study, 1957–1963 to 1989–1990. Am J Epidemiol 1993;138:973–83. Zuurbier M, Lundqvuist C, Salines G, Stansfeld S, Hanke W, Babisch W, et al. The environmental health of children: priorities in Europe. IJOMEH 2007;20:291–308.
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Science of the Total Environment j o u r n a l h o m e p a g e : w w w. e l s ev i e r. c o m / l o c a t e / s c i t o t e n v
Blood pressure of 8–14 year old children in relation to traffic noise at home — Results of the German Environmental Survey for Children (GerES IV) Wolfgang Babisch a,⁎, Hannelore Neuhauser b,1, Michael Thamm b,2, Margarete Seiwert a,3 a b
Federal Environment Agency, Department of Environmental Hygiene, Corrensplatz 1, 14195 Berlin, Germany Robert Koch Institute, Department of Epidemiology and Health Reporting, General-Pape-Str. 62-66, 12101 Berlin, Germany
a r t i c l e
i n f o
Article history: Received 29 May 2009 Received in revised form 21 July 2009 Accepted 7 August 2009 Available online 2 September 2009
a b s t r a c t Objectives: The German Environment Agency carried out its fourth German Environmental Survey (GerES IV) from 2003 to 2006, which was especially for children. 1048 children, 8–14 years of age, were randomly selected from all over Germany. The sample is representative of children in this age group living in Germany with respect to gender, community size, and region. Methods: Blood pressure was measured under standardized conditions at clinical study centers. During home visits the children and their parents were asked about leisure activities, housing conditions and environmental factors, including traffic exposure of their homes. Orientating short-term noise measurements were carried out in front of the children's (bed-) room to validate the subjective ratings of the traffic volume (categories: no street, low, moderately, high/extremely high). Results: With respect to the subjective rating of “type of street” (traffic volume) the lowest blood pressure readings were found in children whose room was facing a street with ‘low traffic’. The highest readings were found in the group where the children's rooms were facing a street with a ‘high or extremely high traffic’ volume. The difference between the two groups was 1.8 mm Hg (95% CI: 0.1 to 3.5, p = 0.036) for systolic and 1.0 mm Hg (95% CI: − 0.4 to 2.4, p = 0.148) for diastolic blood pressure. With respect to the short-term noise measurements, significant blood pressure increases of 1.0 mm Hg (95% CI: 0.3 to 1.6, p = 0.004) and 0.6 mm Hg (95% CI: 0.1 to 1.2, p = 0.025), respectively, were found per 10 dB(A) increment of the noise level. Conclusions: The results show that road traffic noise at home is a stressor that could affect children's blood pressure. © 2009 Elsevier B.V. All rights reserved.
1. Introduction Noise affects children in many ways. Exposure to transport noise can lead to annoyance, stress responses, cognitive impairment and possibly cardiovascular problems (Zuurbier et al., 2007). Noise effects in children may be different from those in adults because the timeactivity patterns of children differ from those of adults (Bistrup et al., 2006). Adults and children are exposed to the same environmental noises while sleeping at night. However, children go to bed earlier and sleep longer — and thus may be exposed to daytime noise during sleep. Especially very young children cannot determine their acoustic environment. They have less control over their environment than adults.
⁎ Corresponding author. Tel.: +49 30 8903 1370; fax: +49 30 8903 1830. E-mail addresses: [email protected] (W. Babisch), [email protected] (H. Neuhauser), [email protected] (M. Thamm), [email protected] (M. Seiwert). 1 Tel.: +49 30 18754 3462; fax: +49 30 18754 3555. 2 Tel.: +49 30 18754 3204; fax: +49 30 18754 3211. 3 Tel.: +49 30 8903 1370; fax: +49 30 8903 1311. 0048-9697/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.scitotenv.2009.08.016
Effects of noise on children's blood pressure have been investigated with respect to road traffic noise and aircraft noise (Babisch, 2006). The results were contradictory. Aircraft noise was mostly assessed at schools. However, since the children normally lived within the vicinity of the schools, the noise assessment also reflected the exposure at home. Higher systolic and/or diastolic blood pressure readings in higher noise-exposed subjects were primarily found in children exposed to aircraft noise in the Los Angeles studies (Cohen et al., 1980; Cohen et al., 1981), the Munich studies (Evans et al., 1995), and in the Dutch sub-sample of the RANCH studies carried out around Amsterdam airport (van Kempen et al., 2006). However, nilresults were found in the UK sample of the RANCH study (van Kempen et al., 2006) and the Sydney studies (Morrell et al., 1998, 2000). With respect to road traffic noise, only in the study carried out in Bratislava were higher blood pressure readings found in children exposed to road traffic noise at home and at day care centers (Regecová and Kellerová, 1995). Nil-results were found in the UK sample of the RANCH study (van Kempen et al., 2006) and the Tyrol studies (Evans et al., 2001; Lercher, 1992); negative findings were found in the Dutch sample of the RANCH study (van Kempen et al., 2006). The differences of mean blood pressure readings between
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‘exposed’ and ‘non-exposed’ children, if any, were very slight (1 to 5 mm Hg), depending on the noise level contrast. As being part of a nation-wide environment and health survey the blood pressure and the exposure to noise from road traffic were assessed in a representative sample of children in Germany. 2. Methods The noise annoyance of 8–14 year old children was assessed in a random population sample within the framework of the “German Environmental Survey for Children (GerES IV)”. The survey was carried out from 2003 to 2006 by the German Federal Environment Agency. The participants were a sub-sample of the “Health Interview and Examination Survey for Children and Adolescents (KiGGS)”, which was carried out by the Robert Koch Institute (Kurth et al., 2008). Details of the sampling procedure and the study design are given elsewhere (Babisch, 2009; Becker et al., 2005; Schulz et al., 2008). The sampling procedure of this cross-sectional KiGGS survey was based on a two-stage protocol. First, a systematic sample of primary sample units (KiGGS: 167, GerES IV:150) was drawn from an inventory of German communities stratified by the grade of urbanization and the geographical distribution. At the second stage, an equal number of addresses per birth cohort were randomly selected from local population registers within the primary sample units. In a third step the GerES IV sample was drawn, which included 1790 3–14 year old children that were randomly selected from the pool of subjects (parents) that had given their consent for participation in the survey. The total response rate (KiGGS + GerES IV) was 52.6%. The GerES IV sample is representative of children in this age group living in Germany with respect to gender, community size, and region. According to the noise assessment protocol of the survey, all noise-related analyses refer to the sub-sample of 8–14 year old children (N = 1048), who also additionally had a hearing test. The statistical analyses were carried out using the statistical software package SPSS15. Depending on the scale-level Chi2-, Gamma-, and Mann–Whiney-Tests were carried out to assess associations. Multiple variance analyses to control for covariates were carried out using the procedure UNIANOVA. The parents were asked to classify the type of street on which their dwelling was located (categories: ‘low traffic side street’, ‘moderate traffic side street’, ‘heavy traffic side street’, ‘busy main road or major trunk road’). In the case of more than one relevant street, answers were to be given with respect to the busiest street. The parents were also asked whether the child's room was facing this street. Furthermore, during the home visit the parents rated the traffic volume of the street to which the children's room windows were facing (question: “Is there a street right in front of the children's bedroom window — yes/no? If yes, how would you characterize the traffic volume of this street — low/moderate/busy/extremely busy?” For statistical analyses these two answers were combined to the categories: ‘no street’, ‘low traffic street’, ‘moderate traffic street’, ‘busy street’, ‘extremely busy street’). For validation, the interviewers rated the traffic volume of the street using the same scale in a separate questionnaire. The ratings were very similar (Gamma-coefficient = 0.993, p < 0.000). In the following analyses the parent's ratings were used, because they were based on much longer experience of the traffic conditions, including the night. During the home visit an approx. 15 min integrating orientating noise measurement was taken in front of the child's open room window (sound level meter NORSONIC Type 116); LASm, LASmax, and LApeak were recorded. The measurements were carried out between 8:00 and 21:30, depending on the time of the visit (mean 15:22, standard deviation: 2:21). Across 10 areal agglomeration levels (range: ≤ 2000–≥ 500,000 inhabitants) no distributional differences of the time of the measurements were found. Considering the fact that variations greater than ± 3 dB(A) (double/half of the traffic volume) are
very unlikely to happen throughout the daytime — particularly on busy roads, no weighting of noise levels depending on the time of the day was applied. The crude noise measurements were considered as reasonable additional information for epidemiological purposes on a group level and for validation of the subjective scales regarding type of street and traffic volume. Other permanent noise sources than road traffic that might have been the primary sources were documented by the interviewer (e. g. railway: 0.5%, aircraft: 1.4%, industry: 0.6%, construction: 2.1%, neighborhood: 19.5%, natural sounds 25.1% of the measurements). High peak noise levels may be an indicator for confounding noise sources. Both kinds of information were used for sensitivity analyses. Annoyance of the children from road traffic noise was assessed by questionnaire during home visits (face to face interview). A dichotomous annoyance scale (‘yes/no’) was applied to the 8–10 year old children (n = 448), and a numerical 5-point scale (‘not at all/ slightly/moderately/very/extremely’) was applied to the 11–14 year old children (n = 600) in the style of the German version (FelscherSuhr et al., 2000) of the recommendations for the assessment of annoyance in community noise studies (Fields et al., 2001). A distinction was made between the annoyance during the day and the night. The medical data of all the children were assessed at ad-hoc clinics that where set up in the study areas. Resting blood pressure measurements were carried out twice at a two minute interval under standardized conditions using an automatic device (Datascope Accutorr Plus). The measurement was carried out after 5-minute rest in the sitting position (right arm). Details are given elsewhere (Neuhauser and Thamm, 2007).Oscillometric systolic and diastolic blood pressure and heart rate were measured. The average of the two measurements was used for further analyses. Height and weight of the children were considered in the analyses as covariates to control for confounding. Both show a largely steady trend with blood pressure in children (Michels et al., 1998; Neuhauser and Thamm, 2007). Physical activity was assessed differently in the 8–10 and the 11– 14 year old children. The parents of the younger children were asked how frequent their children played outdoors and carried out sports. The older children answered themselves with respect to the frequency and the duration of heavy exercises in their leisure time. Stratified analyses were carried out within each age group to assess the impact of the inclusion of these variables on the association between road traffic noise and blood pressure. An indicator variable was created that was used in the total sample for control of confounding (8–10 year old children: ‘physical active’ = playing outdoors nearly every day or carrying out sports at least once per week, ‘physical inactive’ = others; 11–14 year old children: ‘physical active’ = heavy exercise at least once a week, ‘physical inactive’ = others). All descriptive analyses were stratified according to a set of sociodemographic variables, including age (8–10, 11–12, 13–14 years), gender (boys, girls), area (eastern, western Germany), socio-economic status (low, medium, high — based on ‘Winkler’ index (Kurth et al., 2008)), migrant status (German, non-German citizenship), and agglomeration size (<100,000, ≥100,000). Individual data regarding the exposure to (outdoor) air pollutants were not available (random sample from all over Germany). However, although air pollution was found to be associated with myocardial infarction and mortality, there is not much evidence that it is associated with high blood pressure, particularly in children (European Respiratory Society, 2006; Jarup et al., 2007; The PEP, 2009). 3. Results 16.5% of the children lived in dwellings on a ‘busy main road or a major trunk road’, 11.7% on a ‘heavy traffic side street’, 31.1% on a ‘moderate traffic side street’, and 40.6% on a ‘low traffic side street’.
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The proportion of children with a room with windows facing the street increased (Chi2-Trend-Test: p < 0.001) with increasing noise exposure across the four street categories from 45% (‘low traffic side street’) to 61% (‘busy main road or major trunk road’). Nearly half of the children's rooms (47.7%) had windows not facing a street. Table 1 shows the distribution of children over the type of street categories, referring to the street in front of the children's room. 13.9% of the children's room windows were facing a ‘busy traffic street’ or an ‘extremely busy traffic street’. The 15-minute average noise levels which were measured in front of the children's room showed a symmetric distribution, ranging from 27 to 86 dB(A) (mean: 50, standard deviation: 7). Maximum noise levels (“slow”) ranged between 36 and 94 dB(A), peak noise levels between 39 and 115 dB(A). Non-parametric correlation coefficients between the ordinary scale of traffic volume in front of the children's room and the noise levels were: 0.56 (LASm: rs = 0.56, LAmax: rs = 0.37, LApeak: rs = 0.18), indicating that the verbal graduates of the traffic volume correlate well with the short-term average noise level. Table 1 and Fig. 1 show the mean noise levels (LASm) and 95 percent confidence intervals for different subjective type of street categories. Table 2 shows the distribution of children over the annoyance categories regarding the annoyance due to road traffic noise during the day and the night. The results of the 8–10 and 11–14 year old children are shown separately, because different annoyance scales were used for the 8–10 and 11–14 year old children. Blood pressure and heart rate showed a largely symmetric distribution. Only the systolic blood pressure was slightly skewed due to a few high readings. Table 3 shows the mean blood pressure reading, including 95% confidence intervals, of the children for each type of street category. The results are model-adjusted (UNIANOVA) with respect to age, gender, area, socio-economic status, migrant status, agglomeration size, height, weight and physical activity. Higher blood pressure readings are found in children exposed to noise from busy streets. When the upper two exposure categories are taken together (‘busy traffic street’ and ‘extremely busy traffic street’) and ‘low traffic street’ is taken as the reference category (statistical test of contrast), the difference between the two extreme groups is 1.8 mm Hg (95% CI: 0.1 to 3.5, p = 0.036) for systolic and 1.0 mm Hg (95% CI: − 0.4 to 2.4, p = 0.148) for diastolic blood pressure. The effect on systolic blood pressure is statistically significant. When ‘no street’ is considered as the reference category, the respective differences are 1.2 mm Hg (95% CI: − 0.3 to 2.6, p = 0.126) and 0.5 mm Hg (95% CI: − 0.7 to 1.7, p = 0.441). Stratified analyses using the complete information regarding the physical activity of the 8–10 and 11–14 year old children (which was differently assessed) did not reveal a notable impact of physical activity on the associations between noise and blood pressure in these subgroups. With respect to the short-term noise measurements, multiple linear regression analyses – adjusted for the full set of covariates – revealed significant blood pressure increases of 0.96 mm Hg (95% CI: 0.30 to 1.62, p = 0.004) for systolic and 0.61 mm Hg (95% CI: 0.08 to 1.15, p = 0.025) for diastolic blood pressure per 10 dB(A) increment of the sound level. Fig. 2 shows the scatterplot of the crude unadjusted association between the noise level and the systolic blood pressure
Table 1 Distribution of children and measured short-term noise levels over type of street categories. Street category
Percentage of children
Noise level LASm [dB(A)] Mean (95% confidence interval)
‘No street’ ‘Low traffic street’ ‘Moderate traffic street’ ‘Busy traffic street’ ‘Extremely busy traffic street’
47.7% 20.7% 17.7% 11.1% 2.8%
48 (47–49) 48 (47–49) 52 (51–53) 58 (57–59) 60 (58–63)
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Fig. 1. Association between type of street categories and noise level.
(1.39 mm Hg per 10 dB(A) (95% CI: 0.59 to 2.2, p = 0.001)). No noise effects were found with respect to heart rate. It should be noted that no significant differences were found between the time of the noise measurement and the type of street (‘no street’: mean = 15:17, SD = 2:22; ‘low traffic street’: mean = 15:30, SD = 2.19; ‘moderate traffic street’: mean = 15:15, SD = 2:16; ‘busy traffic street’: mean = 15:35, SD = 2:23; ‘extremely busy street’: mean = 15:19, SD = 2:41). Sensitivity analyses – excluding subjects where the peak noise level exceeded 101 dB(A) (5 percent percentile) or where anthropogenic sound sources were prevalent during the home visit outside the children's room – did not change the results considerably (slightly larger effect estimates were found). When the objective noise indicators were replaced by the subjective indicators of road noise perception (annoyance) a tendency to higher blood pressure readings was found in the group of 8–10 year old children who were annoyed during the day or during the night by road traffic noise. The results from this group as shown in Table 4, however, were not statistically significant. Table 5 shows the results of the group of 11–14 year olds. Subjects that were ‘slightly’, ‘moderately’, ‘very’ or ‘extremely’ annoyed = ‘little’ annoyed were taken together due to small numbers (low annoyance of the children, see Table 2). A tendency towards lower blood pressure readings was found in those children who were annoyed during the night by road traffic noise, which was found to be significant (p = 0.012) for diastolic blood pressure. 4. Discussion The association between road traffic noise and blood pressure was investigated in 1048 children, 8–14 year of age. The children Table 2 Distribution of children over road traffic noise annoyance categories. Annoyance rating
8–10 year old children
11–14 year old children
Day
Night
Day
Night
‘No’ ‘Yes’ ‘Not at all’ ‘Slightly’ ‘Moderately’ ‘Very’ ‘Extremely’
92.8% 7.2%
93.3 6.7 81.7 14.3 3.2 0.7 0.1
91.8 5.4 2.2 0.5 0.1
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Table 3 Mean (95% confidence intervals) systolic and diastolic blood pressure readings of 8–10 year old children by type of street categories. Street category
Systolic blood pressurea [mm Hg]
Diastolic blood pressurea [mm Hg]
‘No street’ ‘Low traffic street’ ‘Moderate traffic street’ ‘Busy traffic street’ ‘Extremely busy traffic street’
108.7 108.0 108.5 109.8 109.9
65.3 64.8 65.1 65.9 65.6
(107.5–109.8) (106.5–109.5) (107.1–109.9) (108.1–111.5) (106.8–112.9)
(64.4–66.3) (63.6–66.0) (64.0–66.3) (64.5–67.3) (63.1–68.1)
Table 4 Mean (95% confidence intervals) systolic and diastolic blood pressure readings of 8–10 year old children by road traffic noise annoyance. Annoyance rating 8–10 year old children (2 point scale) Day Night
‘No’ ‘Yes’ ‘No’ ‘Yes’
Systolic blood pressurea [mm Hg]
Diastolic blood pressurea [mm Hg]
104.9 105.4 103.0 105.0
63.9 65.5 63.2 64.1
(103.2–106.5) (102.4–108.4) ( 99.8–106.2) (103.4–106.7)
(62.6–65.2) (63.1–67.9) (60.7–65.8) (62.8–65.4)
a Adjusted for age, gender, area, socio-economic status, migrant status, agglomeration size, height, weight and physical activity.
a Adjusted for age, gender, area, socio-economic status, migrant status, agglomeration size, height, weight and physical activity.
participated in the German Environmental Survey for Children (GerES IV) which consists of a sub-sample of the representative German Health Interview and Examination Survey for Children and Adolescents (KiGGS). The exposure to road traffic noise was determined by the parent's classification of the type of road in front of the children's room, and by orientating short-term noise measurements carried out during the day in front of the children's room window. While the noise questionnaire and the noise measurements were applied at home, the blood pressure measurements were carried in ad-hoc medical clinics. The resting blood pressure measurement, in this respect, reflects a chronic state of the children's circulatory system, which was not affected by the acute noise situation at home. Small, but higher systolic and diastolic blood pressure readings were found in children who were exposed to noise from busy streets compared with less exposed children when the type of street was considered as the factor of exposure. The lowest blood pressure readings were found in children whose room was facing a street with ‘low traffic’ volume. The highest readings were found in the group where the children's rooms were facing a street with a ‘high or extremely high traffic’ volume. The mean difference between the two groups was 1.8 mm Hg for systolic and 1.0 mm Hg for diastolic blood pressure. The effect was significant only for systolic blood pressure due to statistical power (sample size). However, it appears also reasonable to assume that manifest arteriosclerotic manifestations of increased blood pressure were not present in those young children. The effect may rather be due to sympathetic arousal, which is more pronounced in systolic blood pressure. The results confirm the findings of a few other studies where slightly higher blood pressure readings were found in children exposed
to high noise level, either at home or at school/day care centers (Karsdorf and Klappach, 1968; Regecová and Kellerová, 1995). However, negative or nil results were also found in studies (Evans et al., 2001; van Kempen et al., 2006; Lercher, 1992). ‘J-shaped’ associations were found when the presumably quietest category (‘no street’) was considered as a reference group. This group had a slightly higher systolic and diastolic blood pressure on average – 0.6 and 0.5 mm Hg, respectively – than the ‘low traffic’ group. This may be due to road traffic in the distance when there was no street right in front of the children's bedroom. Although the 15-minute short-term noise measurements did not reveal a difference in the average equivalent sound pressure level between those groups, children from the ‘no street’ group were slightly more annoyed by road traffic noise than the ‘low traffic’ group (not shown). Different time patterns of the acoustical signals (very few noise events close to the room (‘low traffic’) versus continuous noise from the distance (‘no street’)) might be an explanation for this finding. However, when the noise level was considered as the factor of exposure, significant linear trends of an increase of both, systolic (1.0 mm Hg per 10 dB(A)) and diastolic blood pressure (0.6 mm Hg per 10 dB(A)), with increasing noise levels were found. With respect to annoyance due to road traffic noise, a non-significant tendency to higher blood pressure readings was found in the group of younger children (8–10 years) who were annoyed by noise. In the older children (11–14 years) the opposite was found, which was significant for the association between night-time noise annoyance and diastolic blood pressure. This contradictory finding is difficult to explain. Possibly the older children who had expressed their annoyance had better and more effective ways of coping with the noise (Lercher, 1996). However, the finding could be accidental due to the small numbers of annoyed children. The results were adjusted for potentially confounding factors, including age, gender, area, socio-economic status, migrant status, agglomeration size, height, weight and physical activity. With regard to possible health risks in their later life, the findings in children are difficult to interpret. The effect may be of a temporary nature and may
Table 5 Mean (95% confidence intervals) systolic and diastolic blood pressure readings of 11–14 year old children by road traffic noise annoyance. Annoyance rating 11–14 year old children (5 point scale) Day
Night
Fig. 2. Scatterplot of the association between noise level and systolic blood pressure.
‘Not at all’ ‘Slightly’, ‘moderately’,‘very’ or ‘extremely’ ‘Not at all’ ‘Slightly’, ‘moderately’,‘very’ or ‘extremely’
Systolic blood pressurea [mm Hg]
Diastolic blood pressurea [mm Hg]
111.4 (110.0–112.9) 112.4 (110.5–114.4)
66.4 (65.2–67.6) 66.0 (64.4–67.6)
111.8 (110.4–113.2) 110.1 (107.6–112.7)
66.5 (65.4–67.7) 64.2 (62.1–66.3)
a Adjusted for age, gender, area, socio-economic status, migrant status, agglomeration size, height, weight and physical activity.
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not be relevant to permanent health damage. On the other hand, there is evidence that during childhood (Gillman et al., 1992), adolescence (Yong et al., 1993) and adulthood (Tate et al., 1995) the blood pressure level at an early age is an important predictor of the blood pressure level at a later age. A crude hint regarding reversible effects on blood pressure came from the Sydney study (Morrell et al., 2000). It was concluded that children do not seem to adapt to high levels of road traffic noise but to some extent to aircraft noise (Bistrup et al., 2001; Passchier-Vermeer, 2000). However, the data base appears to be too poor to draw final conclusions. Aircraft noise studies focussed on the exposure at school, while road traffic noise studies mostly considered the noise exposure at home. Different mechanisms (disturbed learning/concentration vs. disturbed relaxation/sleep) may be involved. The conclusions given by Evans and Lepore still seem to hold some truth (Evans and Lepore, 1993): “We know essentially nothing about the long-term consequences of early noise exposure on developing cardiovascular systems. The degree of blood pressure elevations is small. The clinical significance of such changes in childhood blood pressure is difficult to determine. The ranges of blood pressure among noise-exposed children are within the normal levels and do not suggest hypertension. The extent of blood pressure elevations found from chronic exposure are probably not significant for children during their youth, but could portend elevations later in life that might be health damaging.” 5. Conclusions The results of the German Environmental Survey for Children (GerES IV) give some indication that children who are exposed to high levels of road traffic noise may have higher blood pressure. The longterm consequences of those small noise-related blood pressure elevations for children's health remain unclear. Acknowledgments The German Environmental Survey for Children (GerES IV) was funded by the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety, and the Federal Ministry of Education and Research. The authors are indebted to all children who participated in this study, and to their parents. The complex study could not have been realized without the strong commitment of the study team and so many more colleagues in the Robert Koch Institute and the Federal Environment Agency. Disclaimer: Statements and opinions expressed in this article are those of the authors. References Babisch W. Transportation noise and cardiovascular risk: updated review and synthesis of epidemiological studies indicate that the evidence has increased. Noise Health 2006;8(30):1-29. Babisch W. Kinder-Umwelt-Survey (KUS) 2003/06 Lärm. Daten und Materialiensammlung, Deskription und Zusammenhangsanalysen. Umwelt & Gesundheit 01/2009. Umweltbundesamt, Dessau-Roßlau / Bad Elster / Berlin, 2009. Becker K, Schulz C, Babisch W, Dürkop J, Rosskamp E, Seiwert M, et al. German environmental survey for children (GerES IV) 2003–2006. Pollut Atmos 2005;188: 475–9. Bistrup ML, Hygge S, Keiding L, Passchier-Vermeer W. Health effects of noise on children — and perception of risk of noise. Copenhagen: National Institute of Public Health; 2001.
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