title: Changes in traffic exposure and the risk of incident myocardial infarction and all-cause mortality.
abstract: BACKGROUND
  Traffic-related exposures, such as air pollution and noise, have been associated with increased cardiovascular morbidity and mortality. Few studies, however, have been able to examine the effects of changes in exposure on changes in risk. Our objective was to explore the associations of changes in traffic exposure with changes in risk between 1990 and 2008 in the Nurses' Health Study.
  
  
  METHODS
  Incident myocardial infarction (MI) and all-cause mortality were prospectively identified. As a proxy for traffic exposure, we calculated residential distance to roads at all residential addresses 1986-2006 and considered addresses to be "close" or "far" based on distance and road type. To examine the effect of changes in exposure, each consecutive pair of addresses was categorized as: (1) consistently close, (2) consistently far, (3) change from close to far, and (4) change from far to close. We also examined the change in NO2 levels between address pairs.
  
  
  RESULTS
  In time-varying Cox proportional hazards models adjusted for a variety of risk factors, women living at residences consistently close to traffic were at a higher risk of an incident MI (hazard ratio [HR] = 1.11; 95% confidence interval [CI] = 1.01-1.22) and a higher risk of all-cause mortality (1.05; 1.00-1.10), compared with those consistently far. The highest risks were seen among women who moved from being far from traffic to close (incident MI: HR = 1.50 [95% CI = 1.11-2.03]; all-cause mortality: HR = 1.17 [95% CI = 1.00-1.37]). Each 1 ppb increase in NO2 compared with the previous address was associated with a HR = 1.22 for incident MI (95% CI = 0.99-1.50) and 1.03 for all-cause mortality (95% CI = 0.92-1.15).
  
  
  CONCLUSIONS
  Our results suggest that changes in traffic exposure (measured as roadway proximity or change in NO2 levels) are associated with changes in risk of MI and all-cause mortality.
authors.affiliation: Department of Medicine, Channing Division of Network Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA. Jaime.hart@channing.harvard.edu
authors.forename: Jaime E
authors.initials: JE
authors.lastname: Hart
authors.forename: Eric B
authors.initials: EB
authors.lastname: Rimm
authors.forename: Kathryn M
authors.initials: KM
authors.lastname: Rexrode
authors.forename: Francine
authors.initials: F
authors.lastname: Laden
mesh_terms: D000328:Adult; D000397:Air Pollution / Q000009:adverse effects*; D002423:Cause of Death / Q000639:trends; D004781:Environmental Exposure / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D015994:Incidence; D008875:Middle Aged; D009203:Myocardial Infarction / Q000453:epidemiology* / Q000401:mortality; D009569:Nitric Oxide / Q000032:analysis; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012111:Residence Characteristics / Q000706:statistics & numerical data; D018570:Risk Assessment; D014481:United States / Q000453:epidemiology; D001335:Vehicle Emissions / Q000633:toxicity*
chemical_list: D001335:Vehicle Emissions; D009569:Nitric Oxide