Transportation noise exposure is increasing because of rapid urbanization and transportation
growth. Environmental noise exposure affects a large part of the population and gives rise to
widespread annoyance and sleep disturbances. However, the evidence on metabolic and
cardiovascular effects of long-term exposure to transportation noise from different sources is
mostly limited and of low quality, hampering comprehensive risk assessment, although such
effects may be of great public health significance. The main aim of this thesis was to study
the development of obesity and cardiovascular outcomes in relation to exposure to noise from
road traffic, railways and aircraft, and particularly the role of interactions.
The four cohorts under study were based in Stockholm County and included a total of more
than 22,000 adults followed for up to 20 years. Three of the papers in the thesis used only one
of these cohorts, the SDPP cohort, including close to 8,000 subjects at recruitment. Individual
assessment of exposure to noise from road traffic, railways or aircraft was based on a detailed
residential history for each study participant as well as a newly developed database
containing longitudinal information on determinants of noise levels generated by the three
transportation noise sources. Data on air pollution exposure was obtained from dispersion
models based on a similar methodology. Information on covariates and health outcomes was
based on questionnaires and registers, and the health outcome data were further supplemented
with information from clinical investigations.
For obesity markers, the strongest associations were observed in relation to aircraft noise. A
10 dB higher level in exposure was associated with a waist circumference increase and
weight gain of 0.16 cm/year (95% CI 0.14–0.17) and 0.03 kg/year (95% CI 0.01–0.04),
respectively. Road traffic noise exposure was related to a waist circumference increase of
0.04 cm/year (95% CI 0.02–0.06) per 10 dB Lden, while no clear association was observed for
railway noise. The incidence rate ratio of central obesity in relation to number of sources of
transportation noise exposure increased from 1.22 (95% CI 1.08–1.39) among those exposed
to only one source to 2.26 (95% CI 1.55–3.29) among those exposed to all three
transportation noise sources. Moreover, aircraft noise exposure was related to incidence of
hypertension (hazard ratio: 1.16; 95% CI 1.08–1.24 per 10 dB Lden), but no associations
appeared for other transportation noise sources. No clear or consistent associations were
observed between transportation noise exposure and risk of ischemic heart disease (IHD) or
stroke. However, there appeared to be an increased risk of IHD in women related to road
traffic noise exposure, while the opposite held true for men. Higher risks appeared of both
IHD and stroke incidence in those exposed to all three noise sources, with hazard ratios of
1.57 (95% CI 1.06–2.32) and 1.42 (95% CI 0.87–2.32), respectively.
In conclusion, our findings indicate adverse effects of long-term transportation noise
exposure on some metabolic and cardiovascular outcomes, and suggest that combined
exposure to different transportation noise sources may be particularly harmful
