Associations of Combined Exposures to Surrounding Green, Air Pollution, and Road Traffic Noise with Cardiometabolic Diseases

Abstract

Background: Surrounding green, air pollution, and noise have been associated with cardiometabolic diseases, but most studies have assessed only one of these correlated exposures.

Objectives: We aimed to evaluate associations of combined exposures to green, air pollution, and road traffic noise with cardiometabolic diseases.

Methods: In this cross-sectional study, we studied associations between self-reported physician-diagnosed diabetes, hypertension, heart attack, and stroke from a Dutch national health survey of 387,195 adults and residential surrounding green, annual average air pollutant concentrations [including particulate matter with aerodynamic diameter [Formula: see text] ([Formula: see text]), PM with aerodynamic diameter [Formula: see text] ([Formula: see text]), nitrogen dioxide ([Formula: see text]), and oxidative potential (OP) with the dithiothreitol (DTT) assay ([Formula: see text])] and road traffic noise. Logistic regression models were used to analyze confounding and interaction of surrounding green, air pollution, and noise exposure.

Results: In single-exposure models, surrounding green was inversely associated with diabetes, while air pollutants ([Formula: see text], [Formula: see text]) and road traffic noise were positively associated with diabetes. In two-exposure analyses, associations with green and air pollution were attenuated but remained. The association between road traffic noise and diabetes was reduced to unity when adjusted for surrounding green or air pollution. Air pollution and surrounding green, but not road traffic noise, were associated with hypertension in single-exposure models. The weak inverse association of surrounding green with hypertension attenuated and lost significance when adjusted for air pollution. Only [Formula: see text] was associated with stroke and heart attack.

Conclusions: Studies including only one of the correlated exposures surrounding green, air pollution, and road traffic noise may overestimate the association of diabetes and hypertension attributed to the studied exposure. https://doi.org/10.1289/EHP3857.

Figure 1.

Schematic overview of the analyses performed for two exposures and one health outcome. The black solid lines represent hypothesized causal relationships; the black dashed line represents a noncausal relationship. Note: NDVI, Normalized Difference Vegetation Index; OP^DTT, oxidative potential (OP) metric with dithiothreitol (DTT).

Figure 2.

Spearman correlations between surrounding green, air pollution, road traffic noise, and neighborhood socioeconomic status (SES). Clockwise pies denote positive correlations, and counterclockwise pies denote negative correlations. Note: All correlations are statistically significant, different from 0.0 ($p<0.005$). Surrounding green space in a $300\text{-}\mathrm{m}$ buffer based on TOP10NL; surrounding green space in a $\mathrm{1,000}\text{-}\mathrm{m}$ buffer based on TOP10NL. NDVI, Normalized Difference Vegetation Index; ${\mathrm{NO}}_2$, nitrogen dioxide; ${\text{OP}}^{\text{DTT}}$, oxidative potential (OP) metric with dithiothreitol (DTT); ${\text{OP}}^{\text{ESR}}$, oxidative potential (OP) metric with electron spin resonance; ${\mathrm{PM}}_{2.5}$, PM with aerodynamic diameter $\le 2.5\mathrm{\mu }\mathrm{m}$; ${\mathrm{PM}}_{10}$, particulate matter with aerodynamic diameter $\le 10\mathrm{\mu }\mathrm{m}$.

Figure 3.

Joint odds ratios (JORs) for associations of air pollution, road traffic noise, and decreased surrounding green with diabetes and hypertension. The JORs are based on the CRI methods and represents the odds for a 1-unit [interquartile range (IQR)] increase in air pollution and road traffic noise and a 1-unit decrease in surrounding green exposure relative to the odds for no increase (no decrease in surrounding green) in any of the exposures. Results are given as JOR [95% confidence interval (CI)] per continuous increase for air pollution and road traffic noise and decrease for surrounding green (IQR for Normalized Difference Vegetation Index (NDVI) $300\mathrm{m}$: 0.13, IQR for ${\text{OP}}^{\text{DTT}}$: $0.27{\text{nmol}\text{DTT}/\text{min}/\mathrm{m}}^3$, IQR for ${\mathrm{NO}}_2$: $7.85{\mathrm{\mu }\mathrm{g}/\mathrm{m}}^3$, increment for road traffic noise: $5\text{dB}$) (main model). ^bORs are based on effect estimates of single-exposure models, ^cJORs are based on effect estimates of two-exposure models, ^dJORs are based on effect estimates of three- or four-exposure models. Note: ${\mathrm{NO}}_2$, nitrogen dioxide; ${\text{OP}}^{\text{DTT}}$, oxidative potential (OP) with the dithiothreitol (DTT) assay.