Long-term exposure to air pollution, road traffic noise, and heart failure incidence: the Danish Nurse Cohort

Abstract

BACKGROUND AND AIM: Air pollution has been recognized as a risk factor for ischemic and coronary cardiovascular disease, while evidence on heart failure (HF) is more limited and novel. Moreover, no studies considered possible combined effects of co-exposure to air pollution and noise on HF, as high exposure to one pollutant may make the body more susceptible to the hazardous effects of another pollutant. We examined the association of long-term exposure to air pollution and road traffic noise with incident HF. METHODS: Using data on female nurses from the Danish Nurse Cohort ( 44 years), we investigated associations between 3-year mean exposures to air pollution and road traffic noise and incident HF using Cox regression models, adjusting for relevant confounders. Incidence of HF was defined as the first hospital contact (inpatient, outpatient, or emergency) between cohort baseline (1993 or 1999) and December 31, 2014, based on the Danish National Patient Register. Annual mean levels of particulate matter with a diameter 2.5 µm (PM2.5) since 1990, and nitrogen dioxide (NO2) and road traffic noise (Lden) since 1970 were estimated at participants' residences. RESULTS:Of the 22,189 nurses, 484 developed HF. We detected associations with all three pollutants, with hazard ratios (HR) and 95% confidence intervals (95% CI) of 1.35 (1.09-1.67), 1.09 (0.98-1.22), and 1.11 (0.99-1.26) per increase of 5.1 µg/m3 in PM2.5, 8.6 µg/m3 in NO2 and 9.3 dB in Lden, respectively. In mutually adjusted models, associations with PM2.5 remained most robust. Combination of exposure to high levels (75th vs. ≤75th percentile) of all three pollutants led to enhanced associations with HF incidence, with an HR of 1.46 (1.03-2.07). Former smokers and nurses with hypertension showed the strongest associations with PM2.5. CONCLUSIONS:We found that long-term exposures to air pollution and road traffic noise were independently and synergistically associated with HF. KEYWORDS: air pollution, cohort study, heart failure, morbidity, road traffic noise