Road traffic noise, air pollution components and cardiovascular events.

Traffic noise and air pollution have been associated with cardiovascular health effects. Until date, only a limited amount of prospective epidemiological studies is available on long-term effects of road traffic noise and combustion related air pollution. This study investigates the relationship between road traffic noise and air pollution and hospital admissions for ischemic heart disease (IHD: International Classification of Diseases (ICD9) 410-414) or cerebrovascular disease (cerebrovascular event [CVE]: ICD9 430-438). We linked baseline questionnaire data to 13 years of follow-up on hospital admissions and road traffic noise and air pollution exposure, for a large random sample (N = 18,213) of inhabitants of the Eindhoven region, Netherlands. Subjects with cardiovascular event during follow-up on average had higher road traffic noise day, evening, night level (L den) and air pollution exposure at the home. After adjustment for confounders (age, sex, body mass index, smoking, education, exercise, marital status, alcohol use, work situation, financial difficulties), increased exposure did not exert a significant increased risk of hospital admission for IHD or cerebrovascular disease. Relative risks (RRs) for a 5 (th) to 95 (th) percentile interval increase were 1.03 (0.88-1.20) for L den; 1.04 (0.90-1.21) for particulate matter (PM 10 ); 1.05 (0.91-1.20) for elemental carbon (EC); and 1.12 (096-1.32) for nitrogen dioxide (NO 2 ) in the full model. While the risk estimate seemed highest for NO 2 , for a 5 (th) to 95 (th) percentile interval increase, expressed as RRs per 1 µg/m 3 increases, hazard ratios seemed highest for EC (RR 1.04 [0.92-1.18]). In the subgroup of study participants with a history of cardiovascular disease, RR estimates seemed highest for noise exposure (1.19 [0.87-1.64] for L den); in the subgroup of elderly RR seemed highest for air pollution exposure (RR 1.24 [0.93-1.66] for NO 2 ).

Air pollution exposure and markers of placental growth and function: the generation R study.

BACKGROUND: Air pollution exposure during pregnancy might affect placental growth and function, perhaps leading to pregnancy complications. OBJECTIVE: We prospectively evaluated the associations of maternal air pollution exposure with markers of placental growth and function among 7,801 pregnant women in the Netherlands. METHODS: We estimated levels of particulate matter ≤ 10 µm in aerodynamic diameter (PM10) and nitrogen dioxide (NO2) at the home address for different periods during pregnancy using dispersion modeling techniques. Pro- and anti-angiogenic factors [placental growth factor (PlGF) and soluble fms-like tyrosine kinase 1 (sFlt-1), respectively] were measured in first- and second-trimester maternal blood and in fetal cord blood samples at delivery. Pulsatility index of the uterine and umbilical arteries was measured by Doppler ultrasound in second and third trimester, and notching was assessed in third trimester. Placenta weight and birth weight were obtained from medical records. RESULTS: Higher PM10 and NO2 exposure levels were associated with lower second-trimester maternal sFlt-1 and PlGF levels. PM10 and NO2 exposures averaged over total pregnancy were associated with higher sFlt-1 and lower PlGF levels in fetal cord blood, consistent with an anti-angiogenic state. PM10 and NO2 exposures were not consistently associated with second- or third-trimester placental resistance indices. NO2 exposure was associated with third-trimester notching (odds ratio 1.33; 95% CI: 0.99, 1.78 per 10-µg/m3 increase in the prior 2 months). PM10 and NO2 exposures were associated with lower placenta weight (-11.8 g; 95% CI: -20.9, -2.7, and -10.7 g; 95% CI: -19.0, -2.4, respectively, per 10-µg/m3 increase in the prior 2 months), but not with placenta to birth weight ratio. CONCLUSIONS: Our results suggest that maternal air pollution exposure may influence markers of placental growth and function. Future studies are needed to confirm these findings and explore the maternal and fetal consequences.

Air pollution exposure estimation using dispersion modelling and continuous monitoring data in a prospective birth cohort study in The Netherlands.

Previous studies suggest that pregnant women and children are particularly vulnerable to the adverse effects of air pollution. A prospective cohort study in pregnant women and their children enables identification of the specific effects and critical periods. This paper describes the design of air pollution exposure assessment for participants of the Generation R Study, a population-based prospective cohort study from early pregnancy onwards in 9778 women in The Netherlands. Individual exposures to PM10 and NO2 levels at the home address were estimated for mothers and children, using a combination of advanced dispersion modelling and continuous monitoring data, taking into account the spatial and temporal variation in air pollution concentrations. Full residential history was considered. We observed substantial spatial and temporal variation in air pollution exposure levels. The Generation R Study provides unique possibilities to examine effects of short- and long-term air pollution exposure on various maternal and childhood outcomes and to identify potential critical windows of exposure.

Chronic air pollution exposure during pregnancy and maternal and fetal C-reactive protein levels: the Generation R Study.

BACKGROUND: Exposure to air pollution has been associated with higher C-reactive protein (CRP) levels, suggesting an inflammatory response. Not much is known about this association in pregnancy. OBJECTIVES: We investigated the associations of air pollution exposure during pregnancy with maternal and fetal CRP levels in a population-based cohort study in the Netherlands. METHODS: Particulate matter (PM) with an aerodynamic diameter ≤ 10 µm (PM10) and nitrogen dioxide (NO2) levels were estimated at the home address using dispersion modeling for different averaging periods preceding the blood sampling (1 week, 2 weeks, 4 weeks, and total pregnancy). High-sensitivity CRP levels were measured in maternal blood samples in early pregnancy (n = 5,067) and in fetal cord blood samples at birth (n = 4,450). RESULTS: Compared with the lowest quartile, higher PM10 exposure levels for the prior 1 and 2 weeks were associated with elevated maternal CRP levels (> 8 mg/L) in the first trimester [fourth PM10 quartile for the prior week: odds ratio (OR), 1.32; 95% confidence interval (CI): 1.08, 1.61; third PM10 quartile for the prior 2 weeks: OR, 1.28; 95% CI: 1.06, 1.56]; however, no clear dose-response relationships were observed. PM10 and NO2 exposure levels for 1, 2, and 4 weeks preceding delivery were not consistently associated with fetal CRP levels at delivery. Higher long-term PM10 and NO2 exposure levels (total pregnancy) were associated with elevated fetal CRP levels (> 1 mg/L) at delivery (fourth quartile PM10: OR, 2.18; 95% CI: 1.08, 4.38; fourth quartile NO2: OR, 3.42; 95% CI: 1.36, 8.58; p-values for trend < 0.05). CONCLUSIONS: Our results suggest that exposure to air pollution during pregnancy may lead to maternal and fetal inflammatory responses.

Air pollution exposure during pregnancy, ultrasound measures of fetal growth, and adverse birth outcomes: a prospective cohort study.

BACKGROUND: Air pollution exposure during pregnancy might have trimester-specific effects on fetal growth. OBJECTIVE: We prospectively evaluated the associations of maternal air pollution exposure with fetal growth characteristics and adverse birth outcomes in 7,772 subjects in the Netherlands. METHODS: Particulate matter with an aerodynamic diameter < 10 µm (PM10) and nitrogen dioxide (NO2) levels were estimated using dispersion modeling at the home address. Fetal head circumference, length, and weight were estimated in each trimester by ultrasound. Information on birth outcomes was obtained from medical records. RESULTS: In cross-sectional analyses, NO2 levels were inversely associated with fetal femur length in the second and third trimester, and PM10 and NO2 levels both were associated with smaller fetal head circumference in the third trimester [-0.18 mm, 95% confidence interval (CI): -0.24, -0.12 mm; and -0.12 mm, 95% CI: -0.17, -0.06 mm per 1-µg/m3 increase in PM10 and NO2, respectively]. Average PM10 and NO2 levels during pregnancy were not associated with head circumference and length at birth or neonatally, but were inversely associated with birth weight (-3.6 g, 95% CI: -6.7, -0.4 g; and -3.4 g, 95% CI: -6.2, -0.6 g, respectively). Longitudinal analyses showed similar patterns for head circumference and weight, but no associations with length. The third and fourth quartiles of PM10 exposure were associated with preterm birth [odds ratio (OR) = 1.40, 95% CI: 1.03, 1.89; and OR = 1.32; 95% CI: 0.96, 1.79, relative to the first quartile]. The third quartile of PM10 exposure, but not the fourth, was associated with small size for gestational age at birth (SGA) (OR = 1.38; 95% CI: 1.00, 1.90). No consistent associations were observed for NO2 levels and adverse birth outcomes. CONCLUSIONS: Results suggest that maternal air pollution exposure is inversely associated with fetal growth during the second and third trimester and with weight at birth. PM10 exposure was positively associated with preterm birth and SGA.

Urban road traffic noise and annoyance: the effect of a quiet façade.

Road traffic noise in urban areas is a major source of annoyance. A quiet façade has been hypothesized to beneficially affect annoyance. However, only a limited number of studies investigated this hypothesis, and further quantification is needed. This study investigates the effect of a relatively quiet façade on the annoyance response. Logistic regression was performed in a large population based study (GLOBE, N~18,000), to study the association between road traffic noise exposure at the most exposed dwelling façade (L(den)) and annoyance in: (1) The subgroup with a relatively quiet façade (large difference in road traffic noise level between most and least exposed façade (Q>10 dB); (2) the subgroup without a relatively quiet façade (Q<10 dB). Questionnaire data were linked to individual exposure assessment based on detailed spatial data (GIS) and standard modeling techniques. Annoyance was less likely (OR(Q) (>10)

Trends in aircraft noise annoyance: the role of study and sample characteristics.

Recently, it has been suggested that the annoyance of residents at a given aircraft noise exposure level increases over the years. The objective of the present study was to verify the hypothesized trend and to identify its possible causes. To this end, the large database used to establish earlier exposure-response relationships on aircraft noise was updated with original data from several recent surveys, yielding a database with data from 34 separate airports. Multilevel grouped regression was used to determine the annoyance response per airport, after which meta-regression was used to investigate whether study characteristics could explain the heterogeneity in annoyance response between airports. A significant increase over the years was observed in annoyance at a given level of aircraft noise exposure. Furthermore, the type of annoyance scale, the type of contact, and the response percentage were found to be sources of heterogeneity. Of these, only the scale factor could statistically account for the trend, although other findings rule it out as a satisfactory explanation. No evidence was found for increased self-reported noise sensitivity. The results are of importance to the applicability of current exposure-annoyance relationships for aircraft noise and provide a basis for decisions on whether these need to be updated.

Air pollution, blood pressure, and the risk of hypertensive complications during pregnancy: the generation R study.

Exposure to air pollution is associated with elevated blood pressure and cardiovascular disease. We assessed the associations of exposure to particulate matter (PM(10)) and nitrogen dioxide (NO(2)) levels with blood pressure measured in each trimester of pregnancy and the risks of pregnancy-induced hypertension and preeclampsia in 7006 women participating in a prospective cohort study in the Netherlands. Information on gestational hypertensive disorders was obtained from medical records. PM(10) exposure was not associated with first trimester systolic and diastolic blood pressure, but a 10-µg/m(3) increase in PM(10) levels was associated with a 1.11-mm Hg (95% confidence interval [CI] 0.43 to 1.79) and 2.11-mm Hg (95% CI 1.34 to 2.89) increase in systolic blood pressure in the second and third trimester, respectively. Longitudinal analyses showed that elevated PM(10) exposure levels were associated with a steeper increase in systolic blood pressure throughout pregnancy (P<0.01), but not with diastolic blood pressure patterns. Elevated NO(2) exposure was associated with higher systolic blood pressure levels in the first, second, and third trimester (P<0.05), and with a more gradual increase when analyzed longitudinally (P<0.01). PM(10) exposure, but not NO(2) exposure, was associated with an increased risk of pregnancy-induced hypertension (odds ratio 1.72 [95% CI 1.12 to 2.63] per 10-µg/m(3) increase). In conclusion, our results suggest that air pollution may affect maternal cardiovascular health during pregnancy. The effects might be small but relevant on a population level.

Residential traffic exposure and pregnancy-related outcomes: a prospective birth cohort study.

BACKGROUND: The effects of ambient air pollution on pregnancy outcomes are under debate. Previous studies have used different air pollution exposure assessment methods. The considerable traffic-related intra-urban spatial variation needs to be considered in exposure assessment. Residential proximity to traffic is a proxy for traffic-related exposures that takes into account within-city contrasts. METHODS: We investigated the association between residential proximity to traffic and various birth and pregnancy outcomes in 7,339 pregnant women and their children participating in a population-based cohort study. Residential proximity to traffic was defined as 1) distance-weighted traffic density in a 150 meter radius, and 2) proximity to a major road. We estimated associations of these exposures with birth weight, and with the risks of preterm birth and small size for gestational age at birth. Additionally, we examined associations with pregnancy-induced hypertension, (pre)eclampsia, and gestational diabetes. RESULTS: There was considerable variation in distance-weighted traffic density. Almost fifteen percent of the participants lived within 50 m of a major road. Residential proximity to traffic was not associated with birth and pregnancy outcomes in the main analysis and in various sensitivity analyses. CONCLUSIONS: Mothers exposed to residential traffic had no higher risk of adverse birth outcomes or pregnancy complications in this study. Future studies may be refined by taking both temporal and spatial variation in air pollution exposure into account.

Engineering modeling of traffic noise in shielded areas in cities.

A computational study of road traffic noise in cities is presented. Based on numerical boundary-element calculations of canyon-to-canyon propagation, an efficient engineering algorithm is developed to calculate the effect of multiple reflections in street canyons. The algorithm is supported by a room-acoustical analysis of the reverberant sound fields in the source and receiver canyons. Using the algorithm, a simple model for traffic noise in cities is developed. Noise maps and exposure distributions of the city of Amsterdam are calculated with the model, and for comparison also with an engineering model that is currently used for traffic noise impact assessments in cities. Considerable differences between the two model predictions are found for shielded buildings with day-evening-night levels of 40-60 dB at the facades. Further, an analysis is presented of level differences between the most and the least exposed facades of buildings. Large level differences are found for buildings directly exposed to traffic noise from nearby roads. It is shown that by a redistribution of traffic flow around these buildings, one can achieve low sound levels at quiet sides and a corresponding reduction in the percentage of highly annoyed inhabitants from typically 23% to 18%.

Sex differences in subjective and actigraphic sleep measures: a population-based study of elderly persons.

STUDY OBJECTIVES: To investigate and explain sex differences in subjective and actigraphic sleep parameters in community-dwelling elderly persons. DESIGN: Cross-sectional study. SETTING: The study was embedded in the Rotterdam Study, a population-based study. PARTICIPANTS: Nine hundred fifty-six participants aged 59 to 97 years. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: Participants wore an actigraph and kept a sleep diary for an average of 6 consecutive nights. Subjective sleep quality was assessed with the Pittsburgh Sleep Quality Index. Unadjusted sex differences in sleep parameters were assessed with t tests. Women reported shorter total sleep time, a less favorable sleep-onset latency, lower sleep efficiency, and worse global sleep quality, as compared with men. When assessed with actigraphy, however, women were found to have longer and less-fragmented sleep than men. Sex differences in diary-reported sleep duration and other subjective sleep parameters were attenuated by adjustment for marital status, the use of sleep medication, and other covariates, but all sex differences remained significant in a multivariate-adjusted model. Sex differences in actigraphic sleep parameters were barely attenuated by multivariate adjustment, although the shorter actigraphically measured sleep duration in men was partly explained by their higher alcohol consumption. Some covariates (eg, sleep medication) had a different relationship with diary-reported or actigraphic total sleep time in men and women. CONCLUSIONS: If assessed by diary or interview, elderly women consistently reported shorter and poorer sleep than elderly men. In contrast, actigraphic sleep measures showed poorer sleep in men. These discrepancies are partly explained by determinants of sleep duration, such as sleep medication use and alcohol consumption.

Long-term road traffic noise exposure is associated with an increase in morning tiredness.

This study investigates the association between night time road traffic noise exposure (L(night)) and self-reported sleep problems. Logistic regression was performed in a large population based cohort study (GLOBE), including over 18 000 subjects, to study the association between exposure at the dwelling facade and sleep problems. Measures of sleep problems were collected by questionnaire with two questions: "Do you in general get up tired and not well rested in the morning?" and "Do you often use sleep medication or tranquilizers?" After adjustment for potential confounders, a significant association was found between noise exposure and the risk of getting up tired and not rested in the morning. Although prevalence of medication use was higher at higher noise levels compared to the reference category (L(night)<35 dB), after adjustment for covariates this association was not significant. Long-term road traffic noise exposure is associated with increased risk of getting up tired and not rested in the morning in the general population. This result extends the earlier established relationship between long-term noise exposure and self-reported sleep disturbance assessed with questions that explicitly referred to noise and indicates that road traffic noise exposure during the night may have day-after effects.

Annoyance from environmental noise across the lifespan.

Curvilinear effects of age on self-reported annoyance from environmental noise were investigated in a pooled international and a Dutch sample of in total 62,983 individuals aged between 15 and 102 years. All respondents were frequently exposed to varying levels of transportation noise (i.e., aircraft, road traffic, and railway noise). Results reveal an inverted U-shaped pattern, where the largest number of highly annoyed individuals was found in the middle-aged segment of the sample (peaking around 45 years) while the lowest number was found in the youngest and oldest age segments. This pattern was independent of noise exposure level and self-reported noise sensitivity. The inverted U-shape explains the absence of linear age effects in previous studies. The results are discussed in light of theories predicting an age-related vulnerability to noise.

Habitual traffic noise at home reduces cardiac parasympathetic tone during sleep.

The relationships between road and rail traffic noise with pre-ejection period (PEP) and with respiratory sinus arrhythmia (RSA) during sleep, as indices of cardiac sympathetic and parasympathetic nervous system tone, were investigated in the field (36 subjects, with 188 and 192 valid subject nights for PEP and RSA, respectively). Two analyses were conducted. The first analysis investigated the overall relationships across the entire sleep period. A second analysis investigated differences in the relationships between the first and second halves of the sleep period. Separate multilevel linear regression models for PEP and RSA were employed. Potential covariates for each model were selected from the same pool of variables, which included: gender, age, body-mass index, education level, traffic noise source type, intake of medication, caffeine, alcohol and cigarette smoke, and hindrance during sleep due to the ambulatory recordings. RSA models were adjusted for respiration rate. Mean indoor traffic noise exposure was negatively related to mean RSA during the sleep period, specifically during the second half of the sleep period. Both respiration rate and age were negatively associated with RSA. No significant relationships were observed for PEP. The results indicate that higher indoor traffic noise exposure levels may lead to cardiac parasympathetic withdrawal during sleep, specifically during the second half of the sleep period. No effect of indoor traffic noise on cardiac sympathetic tone was observed.

Long sleep duration is associated with serum cholesterol in the elderly: the Rotterdam Study.

OBJECTIVE: Epidemiological studies have repeatedly found increased mortality associated with both habitual short and long sleep duration. The mechanisms behind these associations are unclear. We investigated whether objectively measured sleep duration, time in bed, and sleep fragmentation were associated with total cholesterol and high density lipoprotein (HDL) cholesterol in community-dwelling elderly. METHODS: This cross-sectional study was conducted among 768 participants of the Rotterdam Study, aged 57 to 97 years. Sleep parameters were assessed with actigraphy, a validated method that infers wakefulness and sleep from arm movement. Cholesterol levels in serum were determined in fasting blood samples. All regression analyses were adjusted for age, gender, body mass index, smoking, depressive symptoms, and heart failure. RESULTS: Sleep duration was positively associated with total cholesterol level: beta = 0.11 (95% confidence interval = 0.03-0.18) mmol/l per hour of sleep. Persons who slept longer, and spent more time in bed, also had a higher total/HDL cholesterol ratio. A less fragmented sleep was also associated with higher total cholesterol. Some of these associations showed significant interactions with age. The association between time in bed and total/HDL ratio was mainly driven by persons aged <65, whereas the relationship between sleep fragmentation and total cholesterol level was most prominent in persons aged >or=70. CONCLUSIONS: A longer sleep duration was related to higher total cholesterol level and a higher total/HDL cholesterol ratio. Two separate mechanisms, a longer time in bed and sleep fragmentation, seem to explain these associations in different age categories.

Disagreement between subjective and actigraphic measures of sleep duration in a population-based study of elderly persons.

Sleep duration is an important concept in epidemiological studies. It characterizes a night's sleep or a person's sleep pattern, and is associated with numerous health outcomes. In most large studies, sleep duration is assessed with questionnaires or sleep diaries. As an alternative, actigraphy may be used, as it objectively measures sleep parameters and is feasible in large studies. However, actigraphy and sleep diaries may not measure exactly the same phenomenon. Our study aims to determine disagreement between actigraphic and diary estimates of sleep duration, and to investigate possible determinants of this disagreement. This investigation was embedded in the population-based Rotterdam Study. The study population consisted of 969 community-dwelling participants aged 57-97 years. Participants wore an actigraph and kept a sleep diary for, on average, six consecutive nights. Both measures were used to determine total sleep time (TST). In 34% of the participants, the estimated TST in the sleep diaries deviated more than 1 h from actigraphically measured TST. The level of disagreement between diary and actigraphic measures decreased with subjective and actigraphic measures of sleep quality, and increased with male gender, poor cognitive function and functional disability. Actigraphically measured poor sleep was often accompanied by longer subjective estimates of TST, whereas subjectively poor sleepers tended to report shorter TST in their diaries than was measured with actigraphy. We recommend, whenever possible, to use multiple measures of sleep duration, to perform analyses with both, and to examine the consistency of the results over assessment methods.

Sleep duration and hypertension are not associated in the elderly.

Several large studies have shown that both short and long average sleep durations increase the risk of hypertension in adults. We investigated whether sleep duration is also associated with hypertension in the elderly. This cross-sectional study was conducted in 5058 participants of the population-based Rotterdam Study, aged 58 to 98 years. Blood pressure was measured at the research center. Hypertension was defined as a systolic blood pressure of >or=160 mm Hg and/or a diastolic blood pressure of >or=100 mm Hg or current use of antihypertensive medication. In all of the participants, sleep duration was assessed by self-report. In a subsample of 975 subjects, it was additionally measured with actigraphy, a validated method that infers wakefulness and sleep from the presence or absence of limb movement. After adjustment for age and gender and additionally for body mass index, smoking, depressive symptoms, sleep medication use, diabetes mellitus, myocardial infarction, and stroke, none of the odds ratios (varying from 0.54; 95% CI: 0.27 to 1.08; to 1.19; 95% CI: 0.89 to 1.58) reflected a significant association between sleep duration and hypertension, whether measured by self-report or actigraphy. This study strongly suggests that sleep duration is not associated with hypertension in the elderly.

Hypertension and road traffic noise exposure.

OBJECTIVE: The purpose of this study was to assess the relationship between road traffic noise exposure at home and the prevalence of hypertension. METHODS: We conducted cross-sectional analyses in a large random sample (N=40,856) of inhabitants of Groningen City, and in a subsample (the Prevention of Renal and Vascular End-Stage Disease [PREVEND]) study cohort; N=8592). RESULTS: Before adjustment for confounders, road traffic noise exposure was associated with self-reported use of antihypertensive medication in the city of Groningen sample (odds ratio [OR]=1.31 per 10-dB increase in Lden). Adjusted odds ratios were significant for the subjects between 45 and 55 years old in the full model when adjusted for PM10 (OR=1.19) and at higher exposure (Lden >55 dB) only (OR=1.21; with adjustment for PM10, OR=1.31). In the PREVEND cohort, the unadjusted odds ratio was 1.35 for hypertension (systolic and diastolic blood pressure >140 and >90 mm Hg, respectively, or use of antihypertensive medication). Again, the adjusted odds ratio was significant for subjects between 45 and 55 years old (OR=1.27; with adjustment for PM10, OR=1.39). CONCLUSIONS: Exposure to road traffic noise may be associated with hypertension in subjects who are between 45 and 55 years old. Associations seemed to be stronger at higher noise levels.

Associations between self-reported sleep disturbance and environmental noise based on reanalyses of pooled data from 24 studies.

This study establishes functions that specify self-reported sleep disturbance in relation to the exposure to nighttime transportation noise, by reanalyzing pooled data from previous studies. Results are based on data from 28 original datasets obtained from 24 field studies (4 studies collected data regarding 2 sources) including almost 23,000 participants exposed to nighttime levels ranging from 45 to 65 dB. Functions are presented that give the percentage highly sleep disturbed, sleep disturbed, and (at least) a little sleep disturbed people due to aircraft, road traffic, and railway noise in relation to the average nighttime outdoor exposure level at the facade most exposed to the source concerned. These functions show that at the same average nighttime noise-exposure level, aircraft noise is associated with more self-reported sleep disturbance than road traffic, and road traffic noise is associated with more sleep disturbance than railways. The association of noise-induced sleep disturbance with age has an inverse U-shape, with the strongest reaction found between 50 and 56 years of age.

Multilevel grouped regression for analyzing self-reported health in relation to environmental factors: the model and its application.

A method for modeling the relationship of polychotomous health ratings with predictors such as area characteristics, the distance to a source of environmental contamination, or exposure to environmental pollutants is presented. The model combines elements of grouped regression and multilevel analysis. The statistical model describes the entire response distribution as a function of the predictors so that any measure that summarizes this distribution can be calculated from the model. With the model, polychotomous health ratings can be used, and there is no need for a priori dichotomizing such variables which would lead to loss of information. It is described how, according to the model, various measures describing the response distribution are related to the exposure, and the confidence and tolerance intervals for these relationships are presented. Specific attention is given to the incorporation of random factors in the model. The application that here serves as an example, concerns annoyance from transportation noise. Exposure-response relationships obtained with the described method of modeling are presented for aircraft, road traffic, and railway noise.