The association between zero-crossing temperatures and accidents due to icy conditions.

AIMS: Rising temperatures lead to milder winters in Scandinavia. In certain regions, this could increase the number of winter days that fluctuate around 0°C (zero crossings). It has been frequently suggested that there is a higher risk of icy conditions during such days, which may lead to a predisposition to falls and road traffic accidents. Here, we examine the association between number of days with zero crossings and the number of hospitalisations and outpatient visits due to falls related to ice or snow or transport accidents. METHODS: We used Poisson regression to examine the association between the number of days with zero crossings and the incidence of inpatient and outpatient visits related to falls due to ice and snow and to transport accidents during 2001-2017 in the Swedish cities of Stockholm, Malmö and Umeå. RESULTS: We found a positive and significant association between the number of days of zero crossings and the number of in- and outpatient cases due to falls related to ice and snow. These associations were strongest in Umeå but less obvious in Stockholm and Malmö. In terms of injuries related to transport accidents, we saw a significant association between inpatient cases and number of zero crossings in Stockholm but not in Malmö or Umeå. CONCLUSIONS: An increased number of zero crossings may increase out- and inpatient visits related to falls due to ice and snow or transport accidents. This effect is more pronounced in the northern city of Umeå than in Malmö, a city in Sweden's southern-most region.

Long-term transportation noise exposure and incidence of ischaemic heart disease and stroke: a cohort study.

BACKGROUND: There is limited evidence from longitudinal studies on transportation noise from different sources and development of ischaemic heart disease (IHD) and stroke. OBJECTIVES: This cohort study assessed associations between exposure to noise from road traffic, railway or aircraft and incidence of IHD and stroke. METHODS: In a cohort of 20 012 individuals from Stockholm County, we estimated long-term residential exposure to road traffic, railway and aircraft noise. National Patient and Cause-of-Death Registers were used to identify IHD and stroke events. Information on risk factors was obtained from questionnaires and registers. Adjusted HR for cardiovascular outcomes related to source-specific noise exposure were computed using Cox proportional hazards regression. RESULTS: No clear or consistent associations were observed between transportation noise and incidence of IHD or stroke. However, noise exposure from road traffic and aircraft was related to IHD incidence in women, with HR of 1.11 (95% CI 1.00 to 1.22) and 1.25 (95% CI 1.09 to 1.44) per 10 dB Lden, respectively. For both sexes taken together, we observed a particularly high risk of IHD in those exposed to all three transportation noise sources at≥45 dB Lden, with a HR of 1.57 (95% CI 1.06 to 2.32), and a similar tendency for stroke (HR 1.42; 95% CI 0.87 to 2.32). CONCLUSION: No overall associations were observed between transportation noise exposure and incidence of IHD or stroke. However, there appeared to be an increased risk of IHD in women exposed to road traffic or aircraft noise as well as in those exposed to multiple sources of transportation noise.

Susceptibility to short-term ozone exposure and cardiovascular and respiratory mortality by previous hospitalizations.

BACKGROUND: Ozone (O3) has been associated with cardiorespiratory mortality although few studies have explored susceptible populations based on prior disease. We aimed to investigate the role of previous hospitalization on the association between short-term exposure to O3 and cardiovascular (CV) and respiratory mortality. METHODS: We performed time series analyses using generalized additive models and case-crossover on 136,624 CV and 23,281 respiratory deaths in Stockholm County (1990-2010). Deaths were linked to hospital admissions data. We constructed 2-day and 7-day averages using daily 8-h maximum for O3 and hourly values for PM2.5, PM10, NO2, and NOx from a fixed monitor. RESULTS: We observed a 0.7% (95% CI: 0.1%, 1.3%) and 2.7% (95% CI: 0.8%, 4.6%) higher risk of CV and respiratory death per 10 µg/m3 higher 2-day and 7-day average O3 respectively. Individuals previously hospitalized for myocardial infarction demonstrated 1.8% (95% CI: 0.4%, 3.4%) higher risk of CV death per 10 µg/m3 higher 2-day average O3 and similar associations were observed in individuals with no previous hospitalization for any cause. Individuals with previous hospitalizations did not show susceptibility towards O3-related risk of respiratory mortality. We observed no associations for other pollutants. CONCLUSION: Short-term ozone exposure is associated with CV and respiratory mortality and our results may suggest higher susceptibility to CV mortality following O3 exposure in individuals previously hospitalized for myocardial infarction. Higher risks were also observed in individuals with cardiovascular death as their first presentation of disease.

Prognosis of Preschool Eczema and Factors of Importance for Remission.

Information on factors of importance for remission of eczema is scarce. This study explored factors related to the remission and course of preschool eczema (PSE) (eczema at 1, 2 and/or 4 years of age) to 16 years of age (n = 889) in a Swedish cohort. Half of the children were in complete remission by school age (at age 8, 12, and 16 years). In multivariate prognostic models, persistent PSE (eczema at 1, 2 and 4 years of age) (odds ratio 0.27 (95% confidence interval 0.18-0.41)), PSE with sleep disturbance (due to itch at least once a week at 1, 2 and/or 4 years of age) (0.59 (0.43-0.81)), parental allergy (0.73 (0.55-0.96)), parental smoking at child's birth (0.70 (0.50-0.99)) and filaggrin mutation (R501X, R2447X, 2282del4) (0.47 (0.26-0.85)) were inversely associated with complete remission by school age. Male sex (1.37 (1.03-1.82)) and exclusive breastfeeding ≥4 months (1.44 (1.01-2.05)) were positively associated with complete remission by school age. In conclusion, half of the children with PSE were in complete remission by school age. The most important prognostic factors were persistent PSE and PSE with sleep disturbance due to itch.

IgE sensitization in relation to preschool eczema and filaggrin mutation.

BACKGROUND: Eczema (atopic dermatitis) is associated with an increased risk of having IgE antibodies. IgE sensitization can occur through an impaired skin barrier. Filaggrin gene (FLG) mutation is associated with eczema and possibly also with IgE sensitization. OBJECTIVE: We sought to explore the longitudinal relation between preschool eczema (PSE), FLG mutation, or both and IgE sensitization in childhood. METHODS: A total of 3201 children from the BAMSE (Children Allergy Milieu Stockholm Epidemiology) birth cohort recruited from the general population were included. Regular parental questionnaires identified children with eczema. Blood samples were collected at 4, 8, and 16 years of age for analysis of specific IgE. FLG mutation analysis was performed on 1890 of the children. RESULTS: PSE was associated with IgE sensitization to both food allergens and aeroallergens up to age 16 years (overall adjusted odds ratio, 2.30; 95% CI, 2.00-2.66). This association was even stronger among children with persistent PSE. FLG mutation was associated with IgE sensitization to peanut at age 4 years (adjusted odds ratio, 1.88; 95% CI, 1.03-3.44) but not to other allergens up to age 16 years. FLG mutation and PSE were not effect modifiers for the association between IgE sensitization and PSE or FLG mutation, respectively. Sensitized children with PSE were characterized by means of polysensitization, but no other specific IgE sensitization patterns were found. CONCLUSIONS: PSE is associated with IgE sensitization to both food allergens and aeroallergens up to 16 years of age. FLG mutation is associated with IgE sensitization to peanut but not to other allergens. Sensitized children with preceding PSE are more often polysensitized.

Short-term Exposure to Ozone and Mortality in Subjects With and Without Previous Cardiovascular Disease.

BACKGROUND: Exposure to ground level ozone (O3) is a public health problem associated with a range of risks across population subgroups. Our aim was to investigate the role of previous cardiovascular diseases (CVDs) in mortality related to short-term O3 exposure. METHODS: Deaths between 1990 and 2010 in Stockholm County were matched with previous hospitalizations in Swedish registries. An urban background monitoring station provided hourly values of air quality data, from which we calculated 8-hour running averages and daily 8-hour maximum. We analyzed associations between daily O3 concentrations and mortality among persons with and without previous CVD hospitalization with a generalized additive model adjusted for time trend, influenza, and weather. We also performed two-pollutant models. RESULTS: There were 302,283 nontrauma-related deaths, out of which 196,916 had previous CVD hospitalization. The mean concentration of daily maximum 8-hour O3 was 62.9 µg/m. An average 10 µg/m increase in the same and preceding day was associated with an increased mortality of 1.72% (95% confidence interval: 0.44%, 3.02%) in those with prior admission for acute myocardial infarction (AMI), which was more than three times higher than for those with no previous AMI (0.50, 95% confidence interval: 0.10%, 0.89%, P value for interaction 0.098). The association between O3 and mortality remained essentially unchanged in two-pollutant models with NO2, NOx, and PM10. CONCLUSIONS: Our study indicates that short-term exposure to O3 is associated with increased mortality in those with a previous hospitalization for AMI.

Short-term effects of air pollution on out-of-hospital cardiac arrest in Stockholm.

BACKGROUND: Although ozone (O3) and other pollutants have been associated with cardiovascular morbidity and mortality, the effects of O3 on out-of-hospital cardiac arrest (OHCA) have rarely been addressed and existing studies have presented inconsistent findings. The objective of this study was to determine the effects of short-term exposure to air pollution including O3 on the occurrence of OHCA, and assess effect modification by season, age, and gender. METHODS AND RESULTS: A total of 5973 Emergency Medical Service-assessed OHCA cases in Stockholm County 2000-10 were obtained from the Swedish cardiac arrest register. A time-stratified case-crossover design was used to analyse exposure to air pollution and the risk of OHCA. Exposure to O3, PM2.5, PM10, NO2, and NOx was defined as the mean urban background level during 0-2, 0-24, and 0-72 h before the event and control time points. We adjusted for temperature and relative humidity. Ozone in urban background was associated with an increased risk of OHCA for all time windows. The respective odds ratio (confidence interval) for a 10 µg/m(3) increase was 1.02 (1.01-1.05) for a 2-h window, 1.04 (1.01-1.07) for 24-h, and 1.05 (1.01-1.09) for 3 day. The association with 2-h O3 was stronger for events that occurred outdoors: 1.13 (1.06-1.21). We observed no effects for other pollutants and no effect modification by age, gender, or season. CONCLUSION: Short-term exposure to moderate levels of O3 is associated with an increased risk of OHCA.

Mortality related to air pollution with the moscow heat wave and wildfire of 2010.

BACKGROUND: Prolonged high temperatures and air pollution from wildfires often occur together, and the two may interact in their effects on mortality. However, there are few data on such possible interactions. METHODS: We analyzed day-to-day variations in the number of deaths in Moscow, Russia, in relation to air pollution levels and temperature during the disastrous heat wave and wildfire of 2010. Corresponding data for the period 2006-2009 were used for comparison. Daily average levels of PM10 and ozone were obtained from several continuous measurement stations. The daily number of nonaccidental deaths from specific causes was extracted from official records. Analyses of interactions considered the main effect of temperature as well as the added effect of prolonged high temperatures and the interaction with PM10. RESULTS: The major heat wave lasted for 44 days, with 24-hour average temperatures ranging from 24°C to 31°C and PM10 levels exceeding 300 µg/m on several days. There were close to 11,000 excess deaths from nonaccidental causes during this period, mainly among those older than 65 years. Increased risks also occurred in younger age groups. The most pronounced effects were for deaths from cardiovascular, respiratory, genitourinary, and nervous system diseases. Continuously increasing risks following prolonged high temperatures were apparent during the first 2 weeks of the heat wave. Interactions between high temperatures and air pollution from wildfires in excess of an additive effect contributed to more than 2000 deaths. CONCLUSIONS: Interactions between high temperatures and wildfire air pollution should be considered in risk assessments regarding health consequences of climate change.

Exposure to air pollution from traffic and neurodevelopmental disorders in Swedish twins.

BACKGROUND: Recent studies have reported associations between air pollution exposure and neurodevelopmental disorders in children, but the role of pre- and postnatal exposure has not been elucidated. AIM: We aimed to explore the risk for autism spectrum disorders (ASD) and attention-deficit hyperactivity disorder (ADHD) among children in relation to pre- and postnatal exposure to air pollution from road traffic. METHODS: Parents of 3,426 twins born in Stockholm during 1992-2000 were interviewed, when their children were 9 or 12 years old, for symptoms of neurodevelopmental disorders. Residence time-weighted concentrations of particulate matter with a diameter <10 µm (PM10) and nitrogen oxides (NOx) from road traffic were estimated at participants' addresses during pregnancy, the first year, and the ninth year of life using dispersion modeling, controlling for seasonal variation. Multivariate regression models were used to examine the association between air pollution exposure and neurodevelopmental outcomes, adjusting for potential confounding factors. RESULTS: No clear or consistent associations were found between air pollution exposure during any of the three time windows and any of the neurodevelopmental outcomes. For example, a 5-95% difference in exposure to NOx during pregnancy was associated with odds ratios (ORs) of 0.92 (95% confidence interval (CI): 0.44-1.96) and 0.90 (95% CI: 0.58-1.40) for ASD and ADHD respectively. A corresponding range in exposure to PM10 during pregnancy was related to ORs of 1.01 (95% CI: 0.52-1.96) and 1.00 (95% CI: 0.68-1.47) for ASD and ADHD. CONCLUSIONS: Our data do not provide support for an association between pre- or postnatal exposure to air pollution from road traffic and neurodevelopmental disorders in children.

Exposure to air pollution from traffic and childhood asthma until 12 years of age.

BACKGROUND: There are limited prospective data on long-term exposure to air pollution and effects on childhood respiratory morbidity. We investigated the development of asthma and related symptoms longitudinally over the first 12 years of life in relation to air pollution from road traffic. METHODS: The Swedish birth cohort BAMSE (Children, Allergy, Milieu, Stockholm, Epidemiological Survey) includes 4089 children who were followed up with repeated questionnaires and blood samples for up to 12 years of age. Residential, daycare, and school addresses, time-activity patterns, emission databases, and dispersion models were used to estimate individual exposure to particulate matter with aerodynamic diameter <10 µm (PM10) and nitrogen oxides (NOx) from traffic. RESULTS: Overall, the data suggested possible associations between exposure to air pollution during the first year of life and asthma and wheezing in children up to 12 years of age. Asthma risks seemed to be particularly increased in children age 8 to 12 years; the overall odds ratio was 2.0 (95% confidence interval = 1.1-3.5), and for nonallergic asthma, the odds ratio was 3.8 (0.9-16.2) for a 5th to 95th percentile increase in time-weighted average exposure to PM10 (corresponding to 7.2 µg/m). Results were similar using exposure to traffic-NOx. CONCLUSIONS: We found modest positive associations between air pollution exposure from traffic during infancy and asthma in children during the first 12 years of life, with stronger effects suggested for nonallergic asthma.

Childhood allergies affect health-related quality of life.

OBJECTIVE: The majority of studies investigating the effects of allergy on the children's health-related quality of life (HRQoL) address one particular allergic disease, using a disease-specific HRQoL instrument. This work aims to assess the comparative impact on HRQoL of several allergic conditions of childhood (asthma, rhinitis, eczema, and food hypersensitivity) in a large, population-based sample of Swedish 8-year-olds. METHODS: Data were obtained from a Swedish birth cohort (BAMSE). At the 8-year follow-up, parents of 3236 children completed the standardized generic HRQoL instrument EQ-5D and reported on the children's symptoms of asthma, rhinitis, eczema, and food hypersensitivity. Information on allergic sensitization and lung function was available for a sub-sample of the children (n = 2370 and 2425, respectively). RESULTS: Children in the study population had a median EQ visual analog scale (VAS) of 98 (Inter Quartile Range, IQR, 90-100). The median EQ VAS was significantly lower in children with allergic diseases. Children with asthma had the lowest median EQ VAS (90, IQR 85-98) and reported the highest prevalence of problems of "pain or discomfort" (18.2%, compared to 5.5% in children without asthma). Frequent wheezing and effort-induced wheezing were associated with high prevalence of problems of "anxiety or depression" (23.3% and 15.4%, respectively). CONCLUSIONS: Swedish 8-year-olds enjoy a good HRQoL, which though is significantly impacted by allergic diseases and particularly by asthma. Asthma symptoms are important determinants of HRQoL and symptom control should be a major goal in asthma management.

Breastfeeding, asthma, and allergy: a tale of two cities.

BACKGROUND: The effect of breastfeeding duration on subsequent asthma and allergy remains the subject of much controversy. OBJECTIVE: To investigate whether differences in study design or disease-related exposure modification were the cause of the differences in study findings. METHOD: The data from two cohorts, the Childhood Asthma Prevention Study (CAPS) from Australia and the Barn Allergi Miljo Stockholm cohort from Sweden, which had reported different findings on the association between breastfeeding and asthma, were combined. For this analysis, the definitions for breastfeeding, asthma, and allergy were harmonized. Subjects were included if they had at least one parent with wheeze or asthma and had a gestational age of more than 36 wks (combined n = 882). The risk of disease-related exposure modification was assessed using survival analysis. RESULTS: Breastfeeding reduced the risk of asthma at 4/5 and 8 yrs of age in children with a family history of asthma. The effect was stronger in the Swedish cohort. Breastfeeding had no effect on the prevalence of sensitization to inhaled allergens in this cohort with a family history of asthma but was a risk factor for sensitization to cow's milk, peanuts, and eggs in the CAPS cohort at 4/5 yrs and in the combined cohort at 8 yrs. There was no evidence to support the existence of disease-related exposure modification in either cohort. CONCLUSION: These findings point to the importance of harmonization of features of study design, including subject selection criteria and variable definitions, in resolving epidemiological controversies such as those surrounding the impact of breastfeeding on asthma and allergic sensitization.

Combined Exposure to Birch Pollen and Thunderstorms Affects Respiratory Health in Stockholm, Sweden-A Time Series Analysis.

BACKGROUND: Thunderstorm asthma is a term used to describe surges in acute respiratory illnesses following a thunderstorm and is often attributed to an intense exposure to aeroallergens. Several episodes of thunderstorm asthma have been observed worldwide; however, no such cases have been described in Sweden. In Sweden, the most prominent exposure to air-borne pollen occurs during the blooming of the birch. We aimed to explore the associations between respiratory health and the combined exposure to thunderstorms and birch pollen. METHODS: We investigated the association between the daily numbers of outpatient visits due to respiratory cases and the combined exposure to thunderstorms and birch pollen during the period of 1 May-31 September in 2001-2017, in Stockholm County, Sweden, by using time series analysis with log linear models. RESULTS: We detected noticeable increases in the number of outpatient visits on both the same day (max 26%; 95% CI 1.16-1.37) and the day after (max 50%; 95% CI 1.32-1.70) the occurrence of a thunderstorm, when the concentrations of birch pollen and the number of lightning discharges were within the highest categories. CONCLUSIONS: It is possible that co-exposure to heavy thunderstorms and high concentrations of birch pollen affects the respiratory health of the Stockholm population. To the best of our knowledge, this is the first study addressing the thunderstorm-related respiratory illnesses in Sweden and the effects of birch pollen. Our study may be important for future public health advice related to thunderstorm asthma.

Mental Health, Greenness, and Nature Related Behaviors in the Adult Population of Stockholm County during COVID-19-Related Restrictions.

International data suggest that exposure to nature is beneficial for mental health and well-being. The restrictions related to the COVID-19 pandemic have created a setting that allows us to investigate the importance of greenness exposure on mental health during a period of increased isolation and worry. Based on 2060 responses from an online survey in Stockholm County, Sweden, we investigated: (1) whether the COVID-19 pandemic changed peoples' lifestyle and nature-related habits, and (2) if peoples' mental health differed depending on their exposure to greenness. Neighborhood greenness levels were quantified by using the average normalized difference vegetation index (NDVI) within 50 m, 100 m, 300 m, and 500 m buffers surrounding the participant's place of residence. We found that the number of individuals that reported that they visited natural areas "often" was significantly higher during the pandemic than before the pandemic. Higher levels of greenness surrounding one's location of residence were in general associated with higher mental health/well-being and vitality scores, and less symptoms of depression, anxiety, and perceived and cognitive stress, after adjustments for demographic variables and walkability. In conclusion, the results from the present study provided support to the suggestion that contact with nature may be important for mental health in extreme circumstances.

Neighbourhood greenness and birth outcomes in a Swedish birth cohort - A short communication.

The present study investigated whether associations between greenness and birth outcomes can be detected in children belonging to a Swedish birth cohort (BAMSE). Normalized difference vegetation index (NDVI) within a 500 m buffer zone around maternal address was used as estimate of greenness. Ordinary least squares and quantile regression models were performed to investigate associations between neighbourhood NDVI and birthweight (n = 2619), birth length (n = 2490) and head circumference (n = 2243). Logistic regression analyses were used to detect the association between NDVI and odds of being born as "small-" or "large-for-gestational-age". There were no clear associations between NDVI and birth weight in the total sample. However, in a suburban sub-sample, increased NDVI levels were significantly associated with elevated birthweight of small new-borns (ß2nd percentile = 276 g, 95% CI 61 to 492, p = 0.012), and significantly reduced the odds ratio (OR) for children being born as small-for-gestational-age (OR = 0.31 95% CI 0.1 to 1, p = 0.049). No significant associations were found between NDVI and birth length or head circumference. In conclusion, neighbourhood greenness appears not to be associated with birthweight as such, but rather decrease the odds of being born underweight, in particular in suburban areas.

Ozone and cardiac arrest: The role of previous hospitalizations.

BACKGROUND: Several studies have reported associations between exposure to particulate matter and incidence of out-of-hospital cardiac arrest (OHCA) and some have observed associations with ozone (O3). There are no studies investigating susceptibility based on previous disease history to short-term O3 exposure and the risk of OHCA. AIM: To investigate the role of previous cardiovascular-related hospitalizations in modifying the associations between the risk of OHCA and short-term increase in O3 concentrations. METHODS: A time-stratified case-crossover analysis of 11,923 OHCA registered in the Swedish Register for Cardiopulmonary Resuscitation from 2006 to 2014 was performed. Using personal identification numbers, OHCA were linked to all previous hospitalizations in Sweden since 1987 to create susceptible groups based on the principal diagnosis code at discharge. Susceptibility was based on hospitalization for i) acute myocardial infarction; ii) heart failure; iii) arrhythmias; iv) diabetes; v) hypertension; and vi) stroke. Moving 2 and 24-h averages for O3, PM2.5, PM10, and NO2 were constructed from hourly averages. RESULTS: A 10 µg/m3 higher 2-h average O3 concentration was associated with a 2% higher risk of OHCA (95% CI, 0% 3%). Associations were similar for 24-h average O3 and in individuals with or without hospitalizations for AMI, heart failure, diabetes, hypertension or stroke. Individuals with previous hospitalizations for arrhythmias had a lower risk of OHCA with higher O3. No associations were observed for other pollutants. CONCLUSIONS: Short-term exposure to O3 was associated with an elevated risk of OHCA, however, previous hospitalizations for cardiovascular diseases were not associated with additionally augmented risks.

Transportation noise and incidence of hypertension.

BACKGROUND: The evidence on exposure to transportation noise and development of hypertension is inconclusive, mostly because of a lack of high quality studies of longitudinal design. OBJECTIVES: This cohort study aimed at investigating the association between exposure to road traffic, railway or aircraft noise and incidence of hypertension. We also assessed effects of varying lengths of exposure as well as of multiple sources of exposure. METHODS: Based on the residential histories of a cohort of 4854 men and women from Stockholm County, we estimated the residential exposure to road traffic, railway and aircraft noise in 1, 5 and 10 year time-periods. Hypertension was assessed by blood pressure measurements, information from questionnaires and hospital diagnoses. Extensive information on potential confounders was available from repeated questionnaires and registers. Hazard Ratios (HR) and 95% confidence intervals (CI) of hypertension related to noise exposure was computed from Cox regression models. RESULTS: We observed a positive association between aircraft noise exposure and incidence of hypertension with a HR of 1.16 (95% CI 1.08-1.24) per 10 dB Lden 5 years preceding the event. No clear differences in risk were indicated between the three exposure time windows. Road traffic and railway noise were not associated with incidence of hypertension during any of the exposure periods. There appeared to be a particularly high risk of hypertension among persons exposed to both aircraft and road traffic noise ≥45 dB Lden with an HR of 1.39 (95% CI 1.14-1.70). CONCLUSIONS: Exposure to aircraft noise may result in increased risk of hypertension.

Road traffic noise and determinants of saliva cortisol levels among adolescents.

OBJECTIVES: The understanding of determinants for saliva cortisol levels in adolescents is limited. This study investigated the role of road traffic noise exposure, noise annoyance and various other factors for saliva cortisol levels. METHODS: We collected morning and evening saliva samples from 1751 adolescents from the BAMSE birth cohort based in Stockholm County. Façade noise levels from road traffic were estimated at the residences of the study subjects and repeated questionnaires and medical examinations provided extensive information on various exposures and conditions, including annoyance to noise from different sources. Cortisol was measured using radioimmunoassay. Associations between determinants and saliva cortisol levels were analysed using linear regression. RESULTS: Morning saliva cortisol levels were significantly higher in females than in males (geometric mean 42.4 and 35.0 nmol/l, respectively) as well as in subjects with allergy related diseases. Height and age were related to saliva cortisol levels as well as sampling season. Road traffic noise exposure was not associated with saliva cortisol, however, annoyance to noise tended to increase the levels. Saliva cortisol levels appeared particularly high among those who were highly annoyed and exposed to road traffic noise levels ≥ 55 dB Lden (50.5 nmol/l, p = 0.02). CONCLUSION: Our findings suggest that individual perception of noise may be of importance for saliva cortisol levels. The results also point to the complexity of using saliva cortisol as a marker of noise exposure in adolescents.