Long-term residential road traffic noise and NO2exposure in relation to risk of incident myocardial infarction - A Danish cohort study.
Road traffic is a source of both air pollution and noise; two environmental hazards both found to increase the risk of ischemic heart disease. Given the high correlation between these pollutants, it is important to investigate combined effects, in relation to myocardial infarction (MI).



Among 50,744 middle-aged Danes enrolled into the Diet, Cancer and Health cohort from 1993 to 97, we identified 2403 cases of incident MI during a median follow-up of 14.5 years. Present and historical residential addresses from 1987 to 2011 were found in national registries, and traffic noise (Lden) and air pollution (NO2) were modelled for all addresses. Analyses were performed using Cox proportional hazard models.



Road traffic noise and NO2were both individually associated with a higher risk of MI, with hazard ratios of 1.14 (1.07-1.21) and 1.08 (1.03-1.12) per inter-quartile range higher 10-year mean of road traffic noise and NO2, respectively. Mutual exposure adjustment reduced the association with 10-year NO2exposure (1.02 (0.96-1.08)), whereas the association with road traffic noise remained: 1.12 (1.03-1.21). For fatal incident MI, the pattern was similar, but the associations for both pollutants were stronger. In analyses of tertiles across both pollutants, the strongest effects were seen for combined medium/high exposure, especially for fatal MI's.



Both road traffic noise and NO2were associated with a higher risk of MI in single-pollutant models. In two-pollutant models, mainly noise was associated with MI. Combined exposure to both pollutants was associated with the highest risk.
Danish Cancer Society Research Center, Strandboulevarden 49, DK-2100 Copenhagen Ø, Denmark. Electronic address: roswall@cancer.dk.
Nina
N
Roswall
Danish Cancer Society Research Center, Strandboulevarden 49, DK-2100 Copenhagen Ø, Denmark; Department of Environmental Science, Aarhus University, Frederiksborgvej 399, DK-4000 Roskilde, Denmark.
Ole
O
Raaschou-Nielsen
Department of Environmental Science, Aarhus University, Frederiksborgvej 399, DK-4000 Roskilde, Denmark.
Matthias
M
Ketzel
Department of Cardiology, Aalborg University Hospital, Hobrovej 18-22, 9000 Aalborg, Denmark.
Anders
A
Gammelmark
Department of Cardiology, Aalborg University Hospital, Hobrovej 18-22, 9000 Aalborg, Denmark; Section for Epidemiology, Department of Public Health, Aarhus University, Bartholins Alle 2, 8000 Aarhus C, Denmark.
Kim
K
Overvad
Danish Cancer Society Research Center, Strandboulevarden 49, DK-2100 Copenhagen Ø, Denmark.
Anja
A
Olsen
Danish Cancer Society Research Center, Strandboulevarden 49, DK-2100 Copenhagen Ø, Denmark.
Mette
M
Sørensen
D000368:Aged; D000393:Air Pollutants / Q000633:toxicity; D003718:Denmark / Q000453:epidemiology; D004781:Environmental Exposure; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018986:Motor Vehicles; D009203:Myocardial Infarction / Q000139:chemically induced / Q000453:epidemiology* / Q000209:etiology; D009585:Nitrogen Dioxide / Q000633:toxicity*; D009624:Noise, Transportation / Q000009:adverse effects*; D011446:Prospective Studies; D011890:Railroads; D012306:Risk; D001335:Vehicle Emissions / Q000633:toxicity
D000393:Air Pollutants; D001335:Vehicle Emissions; D009585:Nitrogen Dioxide
Air pollution; Cohort study; Epidemiology; Myocardial infarction; Traffic noise