Association between Long-Term Exposure to Traffic-Related Air Pollution and Subclinical Atherosclerosis: The REGICOR Study

Marcela Rivera,^1,2,3,4 Xavier Basagaña,^1,2 Inmaculada Aguilera,^1,2,5 Maria Foraster,^1,2,3,5 David Agis,^1,2,5 Eric de Groot,⁶ Laura Perez,^7,8 Michelle A. Mendez,⁹ Laura Bouso,^1,2,5 Jaume Targa,¹⁰ Rafael Ramos,^11,12 Joan Sala,¹³ Jaume Marrugat,¹⁴ Roberto Elosua,^5,14 and Nino Künzli^7,8


¹Centre for Research in Environmental Epidemiology (CREAL), Barcelona, Spain; ²Hospital del Mar Research Institute (IMIM), Barcelona, Spain; ³Universitat Pompeu Fabra, Barcelona, Spain; ⁴University of Montreal Hospital Research Centre (CRCHUM), Montreal, Quebec, Canada; ⁵CIBER Epidemiología y Salud Pública (CIBERESP), Spain; ⁶Department of Vascular Medicine, Academic Medical Centre, Amsterdam, the Netherlands; ⁷Swiss Tropical and Public Health Institute, Basel, Switzerland; ⁸University of Basel, Basel, Switzerland; ⁹University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA; ¹⁰4sfera Innova, Girona, Spain; ¹¹Research Unit, Family Medicine, Jordi Gol Institute for Primary Care Research (IDIAP Jordi Gol), Catalan Institute of Health, Catalunya, Spain; ¹²Department of Medical Sciences, School of Medicine, University of Girona, Girona, Spain; ¹³Servicio de Cardiología, Hospital Universitari Josep Trueta, Institut Català de la Salut, Girona, Spain; ¹⁴Grupo de Epidemiología y Genética Cardiovascular, Hospital del Mar Research Institute (IMIM), Barcelona, Spain


Abstract

Background: Epidemiological evidence of the effects of long-term exposure to air pollution on the chronic processes of atherogenesis is limited.


Objective: We investigated the association of long-term exposure to traffic-related air pollution with subclinical atherosclerosis, measured by carotid intima media thickness (IMT) and ankle–brachial index (ABI).


Methods: We performed a cross-sectional analysis using data collected during the reexamination (2007–2010) of 2,780 participants in the REGICOR (Registre Gironí del Cor: the Gerona Heart Register) study, a population-based prospective cohort in Girona, Spain. Long-term exposure across residences was calculated as the last 10 years’ time-weighted average of residential nitrogen dioxide (NO₂) estimates (based on a local-scale land-use regression model), traffic intensity in the nearest street, and traffic intensity in a 100 m buffer. Associations with IMT and ABI were estimated using linear regression and multinomial logistic regression, respectively, controlling for sex, age, smoking status, education, marital status, and several other potential confounders or intermediates.


Results: Exposure contrasts between the 5th and 95th percentiles for NO₂ (25 µg/m³), traffic intensity in the nearest street (15,000 vehicles/day), and traffic load within 100 m (7,200,000 vehicle-m/day) were associated with differences of 0.56% (95% CI: –1.5, 2.6%), 2.32% (95% CI: 0.48, 4.17%), and 1.91% (95% CI: –0.24, 4.06) percent difference in IMT, respectively. Exposures were positively associated with an ABI of > 1.3, but not an ABI of < 0.9. Stronger associations were observed among those with a high level of education and in men ≥ 60 years of age.


Conclusions: Long-term traffic-related exposures were associated with subclinical markers of atherosclerosis. Prospective studies are needed to confirm associations and further examine differences among population subgroups.


Key words: ankle–brachial index, average daily traffic, cardiovascular disease, exposure assessment, exposure to tailpipe emissions, intima media thickness, land use regression model, Mediterranean diet, nitrogen dioxide. 


Environ Health Perspect 121:223–230 (2013). http://dx.doi.org/10.1289/ehp.1205146 [Online 12 December 2012]


Address correspondence to M. Rivera, University of Montreal Hospital Research Centre (CRCHUM), 3875 Rue Saint-Urbain, 3rd Floor, Office 3.28, H2W1V1 Montreal, Quebec, Canada. Telephone: (514) 890-8000 (ext. 15921). E-mail: marcelaepi@gmail.com


Supplemental Material is available online (http://dx.doi.org/10.1289/ehp.1205146).


We thank M. Medina-Ramón, H. Schröder, M. Grau, J. Vila, P. Solanas, N. Pagès, M. Sidera, M. Pique, S. Tello, R. Martí, M. Cabañero, and L. Franco and the REGICOR team; and W. Hanselaar, J. Gort, M. Dorlijn-Pieterse, and C. van der Biezen-Terlouw of AMC Vascular Imaging, Academic Medical Centre, Amsterdam, the Netherlands, for IMT imaging analysis and training.


J.T. is employed by 4sfera Innova, Girona, Spain. The authors declare they have no actual or potential competing financial interests.


Received 24 February 2012; Accepted 11 December 2012; Online 12 December 2012.