Marie Lewné

Estimating long-term average particulate air pollution concentrations: application of traffic indicators and geographic information systems.

Background. As part of a multicenter study relating traffic-related air pollution with incidence of asthma in three birth cohort studies (TRAPCA), we used a measurement and modelling procedure to estimate long-term average exposure to traffic-related particulate air pollution in communities throughout the Netherlands; in Munich, Germany; and in Stockholm County, Sweden. Methods. In each of the three locations, 40–42 measurement sites were selected to represent rural, urban background and urban traffic locations. At each site and fine particles and filter absorbance (a marker for diesel exhaust particles) were measured for four 2-week periods distributed over approximately 1-year periods between February 1999 and July 2000. We used these measurements to calculate annual average concentrations after adjustment for temporal variation. Traffic-related variables (eg, population density and traffic intensity) were collected using Geographic Information Systems and used in regression models predicting annual average concentrations. From these models we estimated ambient air concentrations at the home addresses of the cohort members. Results. Regression models using traffic-related variables explained 73%, 56% and 50% of the variability in annual average fine particle concentrations for the Netherlands, Munich and Stockholm County, respectively. For filter absorbance, the regression models explained 81%, 67% and 66% of the variability in the annual average concentrations. Cross-validation to estimate the model prediction errors indicated root mean squared errors of 1.1–1.6 &mgr;g/m3 for PM2.5 and 0.22–0.31 *10−5m−1 for absorbance. Conclusions. A substantial fraction of the variability in annual average concentrations for all locations was explained by traffic-related variables. This approach can be used to estimate individual exposures for epidemiologic studies and offers advantages over alternative techniques relying on surrogate variables or traditional approaches that utilize ambient monitoring data alone.

Comparison between different traffic-related particle indicators: elemental carbon (EC), PM2.5 mass, and absorbance.

Here we compare PM2.5 (particles with aerodynamic diameter less than 2.5 μm) mass and filter absorbance measurements with elemental carbon (EC) concentrations measured in parallel at the same site as well as collocated PM2.5 and PM10 (particles with aerodynamic diameter less than 10 μm) mass and absorbance measurements. The data were collected within the Traffic-Related Air Pollution on Childhood Asthma (TRAPCA) study in Germany, The Netherlands and Sweden. The study was designed to assess the health impact of spatial contrasts in long-term average concentrations. The measurement sites were distributed between background and traffic locations. Annual EC and PM2.5 absorbance measurements were at traffic sites on average 43–84% and 26–76% higher, respectively, compared to urban background sites. The contrast for PM2.5 mass measurements was lower (8–35%). The smaller contrast observed for PM2.5 mass in comparison with PM2.5 absorbance and EC documents that PM2.5 mass underestimates exposure contrasts related to motorized traffic emissions. The correlation between PM10 and PM2.5 was high, documenting that most of the spatial variation of PM10 was because of PM2.5. The measurement of PM2.5 absorbance was highly correlated with EC measurements and suggests that absorbance can be used as a simple, inexpensive and non-destructive method to estimate motorized traffic-related particulate air pollution. The EC/absorbance relation differed between countries and site type (background/traffic), supporting the need for site-specific calibrations of the simple absorbance method. While the ratio between PM2.5 and PM10 mass ranged from 0.54 to 0.68, the ratio of PM2.5 absorbance and PM10 absorbance was 0.96–0.97, indicating that PM2.5 absorbance captures nearly all of the particle absorbance.

Myocardial infarction among professional drivers.

Background. Professional drivers are at an increased risk of myocardial infarction but the underlying causes for this increased risk are uncertain. Methods. We identified all first events of myocardial infarction among men age 45–70 years in Stockholm County for 1992 and 1993. We selected controls randomly from the population. Response rates of 72% and 71% resulted in 1067 cases and 1482 controls, respectively. We obtained exposure information from questionnaires. We calculated odds ratios (ORs), with and without adjustment for socioeconomic status, tobacco smoking, alcohol drinking, physical inactivity at leisure time, overweight status, diabetes and hypertension. Results. The crude OR among bus drivers was 2.14 (95% confidence interval = 1.34–3.41), among taxi drivers 1.88 (1.19–2.98) and among truck drivers 1.66 (1.22–2.26). Adjustment for potential confounders gave lower ORs: 1.49 (0.90–2.45), 1.34 (0.82–2.19) and 1.10 (0.79–1.53), respectively. Additional adjustment for job strain lowered the ORs only slightly. An exposure-response pattern (by duration of work) was found for bus and taxi drivers. Conclusions. The high risk among bus and taxi drivers was partly explained by unfavorable life-style factors and social factors. The work environment may contribute to their increased risk. Among truck drivers, individual risk factors seemed to explain most of the elevated risk.

A population-based case-referent study of myocardial infarction and occupational exposure to motor exhaust, other combustion products, organic solvents, lead, and dynamite

This case-referent study investigated the risk of myocardial infarction from occupational exposure to motor exhaust, other combustion products, organic solvents, lead, and dynamite. We identified first-time, nonfatal myocardial infarctions among men and women 45–70 years of age in Stockholm County from 1992 through 1994. We selected referent subjects from the population to match the demographic characteristics of the cases. A lifetime history of occupations was obtained by questionnaire. The response rate was 81% for the cases and 74% for the referents, with 1,335 cases and 1,658 referents included in the study. An occupational hygienist assessed occupational exposures, coding the intensity and probability of exposure for each subject. We adjusted relative risk estimates for tobacco smoking, alcohol drinking, hypertension, diabetes mellitus, overweight, and physical inactivity at leisure time. The relative risk of myocardial infarction was 2.11 (95% confidence interval = 1.23–3.60) among those who were highly exposed and 1.42 (95% confidence interval = 1.05–1.92) among those who were intermediately exposed to combustion products from organic material. We observed an exposure-response pattern, in terms of both maximum exposure intensity and cumulative dose. Exposure to dynamite and organic solvents was possibly associated with an increased risk. The other exposures were not consistently associated with myocardial infarction.

NO2, as a marker of air pollution, and recurrent wheezing in children: a nested case-control study within the BAMSE birth cohort

Aims: To investigate the association between air pollution, including with NO2, and recurrent wheezing during the first two years of life. Methods: A birth cohort (BAMSE) comprised 4089 children, for whom information on exposures, symptoms, and diseases was available from parental questionnaires at ages 2 months, and 1 and 2 years. NO2 was measured during four weeks in and outside the dwellings of children with recurrent wheezing and two age matched controls, in a nested case-control study (540 children). Results: Conditional logistic regression showed an OR of 1.60 (95% CI 0.78 to 3.26) among children in the highest quartile of outdoor NO2 exposure in relation to those in the lowest quartile, adjusted for potential confounders. The corresponding OR for indoor NO2 was 1.51 (95% CI 0.81 to 2.82). An interaction with environmental tobacco smoke (ETS) was indicated with an OR of 3.10 (95% CI 1.32 to 7.30) among children exposed to the highest quartile of indoor NO2 and ETS. The association between NO2 and recurrent wheezing appeared stronger in children who did not fulfil the criteria for recurrent wheezing until their second year. Conclusions: Although the odds of increased recurrent wheezing are not statistically significantly different from one, results suggest that exposure to air pollution including NO2, particularly in combination with exposure to ETS, increases the risk of recurrent wheezing in children.

Bicycle messengers: energy expenditure and exposure to air pollution.

The purpose of the study was to determine the level of energy expenditure and exposure to air pollution for bicycle messengers. Relationships between heart rate (HR) and oxygen uptake, and between HR and pulmonary ventilation (VE) for each participant were established in laboratory tests. Air pollution and HR were measured during one working day. The total oxygen uptake was then described as the total energy expenditure in Joule (J) and in multiples of the energy expenditure at rest (MET). The mean energy expenditure during a working day (8 h) was 12 MJ, (4.8 MET). The level of air pollution exposure when cycling seemed to be comparable with the levels of exposure when sitting inside a vehicle. The VE during cycling was four times higher than resting value. Increased VE led to increased exposure to air pollution.

A Job-Exposure Matrix for Occupational Noise: Development and Validation

OBJECTIVE To develop a job-exposure matrix (JEM) for occupational noise in Sweden and to estimate its validity. METHODS The JEM, developed by a group of experienced occupational hygienists, contains 321 job families with information regarding occupational noise from 1970 to 2004. The occupational noise information derives from measurements collected from different sources. The time period label has a 5-year scale starting in 1970. The estimated average 8h (TWA) noise level in decibel [dB(A)] for every 5-year period was coded either as <75 dB(A), 75-84 dB(A), or ≥85 dB(A) and the risk of peak level exposure assessed. The validity of the JEM is tested, using Svenssons non-parametric methods based on classification consensus, reached by a second group of occupational hygienists. RESULTS/DISCUSSION Validation results show ~ 80% agreement and no systematic differences, in classification, between the two different groups of occupational hygienists, classifying the occupational noise exposure. However, classification of peak level exposure did show a systematic difference in relative position. The results will give more power to the JEM that it gives a good general estimate for the occupational noise levels in Sweden for different job families during 1970-2004. We, thus, intend to use it in further studies and also make it available to collaborators.

Comparison of ambient airborne PM2.5, PM2.5 absorbance and nitrogen dioxide ratios measured in 1999 and 2009 in three areas in Europe

Epidemiological studies often use nitrogen dioxide (NO2) or proximity to roads to characterize exposure to more health-relevant pollutants (e.g., fine particles or black carbon aerosol) in vehicle exhaust. Due to the introduction of diesel-soot filters, particle-to-NO2 ratios may have decreased, but little information is available about these ratios over time. Our study aim was to evaluate the change in particle-to-NO2 ratios between 1999 and 2009. We compared data collected during measurement campaigns in 1999 and 2009 from Munich, the Netherlands, and Stockholm. Traffic-impacted and urban and regional background sites were studied during each campaign. The same pollutants were measured in each campaign (mass concentration of particles ≤ 2.5 microns in diameter (PM2.5), PM2.5 absorbance (a marker for black carbon), and NO2) using the same methods except for NO2: Palmes tubes were used in 1999 and Ogawa badges in 2009. Both NO2 methods were validated against side-by-side chemiluminescence measurements. The levels of PM2.5 absorbance and PM2.5 were significantly lower (p<0.05) in 2009 at traffic and urban background sites in Stockholm, but only slightly lower in Munich and the Netherlands. In contrast, NO2 levels were not significantly different in the three areas in 2009 compared to 1999. Statistically-significant decreases between 1999 and 2009 pollutant ratios in the Netherlands (PM2.5 absorbance/NO2 and PM2.5/NO2) and in Stockholm (PM2.5 absorbance/NO2 and PM2.5 absorbance/PM2.5) were observed. Smaller decreases in these ratios were observed in Munich. The contrast between traffic and urban background locations was larger in 2009 than 1999 for NO2, whereas it was smaller for PM2.5 absorbance and PM2.5. The lower PM2.5 absorbance/NO2 and PM2.5/NO2 ratios in 2009 is likely explained by the introduction of oxidative particle filters for diesel vehicles that reduce particles but produce NO2. The changed contrasts may affect estimates of health effects related to NO2 as a marker of proximity to roads.

Occupational exposure to motor exhaust in Stockholm, Sweden—Different grouping strategies using variability in NO2 to create homogenous groups

AIM The aim of the present study was to investigate the personal variability in occupational exposure to NO(2), as a marker of exposure to diesel exhaust, and to compare a statistical method of grouping workers in homogenous groups with a grouping performed by a qualified occupational hygienist. METHODS Forty-seven workers exposed to motor exhaust in their occupation were included. Personal measurements of NO(2) were performed with diffusive samplers over three full working shifts. The results from the measurements were analysed with a linear mixed effects model, taking both between and within-worker variability into consideration. The workers were divided into occupational groups in different ways in order to find a categorization, with maximal homogeneity in exposure in each group. We used (B)R(0.95) as an estimator of the between-worker variability. To study the effect of the divisions on the fit of the statistical model, we used the Akaike Information Criterion. RESULTS The geometric mean for NO(2) for all 47 workers was 69 μg/m(3) and the between-worker variability (B)R(0.95) was 23.8. In six successive steps, the 47 workers were divided into up to eight groups, based on observed job characteristics. In the final grouping, seven groups were included with geometric means ranging from 32 μg/m(3) for outdoor workers, to 316 μg/m(3) for the most exposed group (tunnel construction workers). The (B)R(0.95) varied between 2.4 and 6.3. The within-worker variability (W)R(0.95) for the last division differed in the groups from 2.0 to 7.9. The Akaike Information Criterion decreased from 246, if all persons were included in one group, to 174 for the final grouping. CONCLUSIONS The average level of NO(2) varied about 10 times between the different occupational groups, with the highest level for tunnel construction workers (316 μg/m(3)) and lowest for outdoor workers (32 μg/m(3)). For four of the seven groups the between-worker variability was higher than the within-worker variability.

Maternal Occupational Exposure to Noise during Pregnancy and Hearing Dysfunction in Children: A Nationwide Prospective Cohort Study in Sweden

Background: Many women of childbearing age are occupationally active, which leads to a large number of pregnancies potentially exposed to occupational exposures. Occupational noise has been identified as a risk factor for hearing impairment in adults. However, very few studies have assessed the effect of occupational noise on the fetus. Objectives: The aim of this study was to investigate whether occupational exposure to noise during pregnancy is associated with hearing dysfunction in children. Methods: This population based cohort study included 1,422,333 single births in Sweden 1986–2008. Data on mothers’ occupation, smoking habits, age, ethnicity, body mass index, leave of absence, and socioeconomic factors were obtained from interviews performed by prenatal care unit staff at approximately 10 weeks of gestation and from national registers. Occupational noise exposure was classified by a job–exposure-matrix as < 75, 75–84, or ≥ 85 dBLAeq,8h. Diagnosed cases of hearing dysfunction (ICD-10 codes H90.3-7, 91.0, 91.2-3, 91.8, 93.1-2) were identified from a register of specialized medical care. Cox proportional hazards models were used to estimate associations. Results: In the full sample, containing a mixture of part-time and full-time workers during pregnancy, the adjusted HR for hearing dysfunction associated with maternal occupational noise exposure ≥ 85 vs. < 75 dBLAeq,8h was 1.27 (95% CI: 0.99, 1.64; 60 exposed cases). When restricted to children whose mothers worked full-time and had < 20 days leave of absence during pregnancy, the corresponding HR was 1.82 (95% CI: 1.08, 3.08; 14 exposed cases). Conclusions: This study showed an association between occupational noise exposure during pregnancy and hearing dysfunction in children. In view of mechanistic evidence and earlier indicative epidemiological and experimental findings, the results support that pregnant women should not be exposed to high levels of noise at work. Citation: Selander J, Albin M, Rosenhall U, Rylander L, Lewné M, Gustavsson P. 2016. Maternal occupational exposure to noise during pregnancy and hearing dysfunction in children: a nationwide prospective cohort study in Sweden. Environ Health Perspect 124:855–860; http://dx.doi.org/10.1289/ehp.1509874