Relationship between Long-Term Exposure to Residential Traffic-Related Air pollution and Noise in a Study of Cardiovascular Disease Risk in Oslo, Norway

Bente Oftedal (1), Gunn Marit Aasvang (1), Ruhina Tasmin Biswas (1), Per Nafstad (1,2), Wenche Nystad (1), Christian Madsen (1), Sam-Erik Walker (3) and PER SCHWARZE (1)

(1) Norwegian Institute of Public Health, Oslo, Norway (2) University of Oslo, Oslo, Norway (3) Norwegian Institute of Air Research, Kjeller, Norway

     Abstract Number: 220
     Last modified: November 9, 2009

Abstract
Background and Objective
Air pollution has been associated with cardiovascular outcomes, and long-term exposure to traffic noise has been linked with increased risk of myocardial infarction and hypertension. Road traffic is the main source of both air pollution and noise. So far, the knowledge about the relative importance of these traffic-related exposures for developing cardiovascular diseases is rather limited.
The aim of the study is to investigate the association between residential nitrogen dioxide (NO2) and traffic noise and the risk of cardiovascular morbidity and mortality. This presentation will describe the study design, exposure assessment and the relationship between residential NO2 and traffic noise.

Methods
A population-based cross-sectional study “The Oslo Health Study” (HUBRO) was conducted in 2000-2001. About 46% (N=18 770) of the invited subjects participated. They answered a questionnaire, and blood pressure, serum cholesterol and serum triglycerides were measured. In 2009 a follow-up questionnaire was submitted, collecting information on noise annoyance, noise sensitivity, sleep disturbances and bedroom orientation. The data will be linked to different health registries including the Death registry of Norway.
Based on emissions, meteorology, topography and background air pollution concentrations, the EPISODE dispersion model calculated hourly NO2 concentrations for each km2 and at thousands of receptor points. NO2 exposure was assigned to each participant’s home addresses during 2000-2006. Traffic noise was assessed for 2006 for buildings within 500m from roads with high traffic counts, 300m from medium traffic roads, 300m from nearest railway and 150m from nearest subway/tram. The noise level indicators Lden (day-evening-night level) and Lnight (nighttime equivalent noise level) were calculated outside the most exposed façade of each house using the Nordic Prediction Method for Railway and Road traffic noise. Those who lived at the same address in 2000 and 2006 were included (N=11 871 for road traffic noise and N=3 325 for railway noise).

Results
The NO2 levels ranged from 0.5 to 65.2 microg/m3. The noise levels (Lden) ranged from 27.1 to 79.5 dB for road traffic noise and from 27.0 to 73.5 dB for railway noise, with lower levels for Lnight. Pearson’s correlation coefficient (r) was 0.44 between NO2 and road traffic noise (Lden) and r=0.16 between NO2 and railway noise.

Conclusion
Differences in modelling of exposure including grid resolution, traffic data and spatial and meteorological aspects may explain the moderate correlations between traffic-related air pollution and road traffic noise. Further insight into the differences and similarities in the assessment approach for each pollutant is necessary to increase the epidemiological knowledge about the potential effects of these environmental exposures in cardiovascular disease.