Adult lung function and long-term air pollution exposure. ESCAPE: a multicentre cohort study and meta-analysis

Abstract

The chronic impact of ambient air pollutants on lung function in adults is not fully understood. The objective of this study was to investigate the association of long-term exposure to ambient air pollution with lung function in adult participants from five cohorts in the European Study of Cohorts for Air Pollution Effects (ESCAPE). Residential exposure to nitrogen oxides (NO₂, NOx) and particulate matter (PM) was modelled and traffic indicators were assessed in a standardised manner. The spirometric parameters forced expiratory volume in 1 s (FEV₁) and forced vital capacity (FVC) from 7613 subjects were considered as outcomes. Cohort-specific results were combined using meta-analysis. We did not observe an association of air pollution with longitudinal change in lung function, but we observed that a 10 μg·m(-3) increase in NO₂ exposure was associated with lower levels of FEV₁ (-14.0 mL, 95% CI -25.8 to -2.1) and FVC (-14.9 mL, 95% CI -28.7 to -1.1). An increase of 10 μg·m(-3) in PM10, but not other PM metrics (PM2.5, coarse fraction of PM, PM absorbance), was associated with a lower level of FEV₁ (-44.6 mL, 95% CI -85.4 to -3.8) and FVC (-59.0 mL, 95% CI -112.3 to -5.6). The associations were particularly strong in obese persons. This study adds to the evidence for an adverse association of ambient air pollution with lung function in adults at very low levels in Europe.

FIGURE 1

Forest plot displaying the study-specific mixed linear regression model estimates of the association of NO₂ with level of forced expiratory volume in 1 s (FEV₁; in mL) (based on all study participants living in sites with ESCAPE models available). NO2_1 indicates NO₂ measured at time of ESCAPE. Associations with lung function measures are presented as increments in NO₂ per 10 μg·m⁻³. I-square: variation in estimated effects attributable to heterogeneity. D+L (Der Simonian and Laird method): pooled estimate of all studies. The mixed linear regression models were adjusted for: age, age squared, height, sex, body mass index, highest educational level, and smoking status at second spirometry; negative estimates indicated lower lung function with increasing exposure. ES: effect size.

FIGURE 2

Forest plot displaying the study-specific mixed linear regression model estimates of the association of NO₂ with level of forced vital capacity FVC; in mL) (based on all study participants living in sites with ESCAPE models available). NO₂_1 indicates NO₂ measured at time of ESCAPE. Associations with lung function measures are presented as increments in NO₂ per 10 μg·m⁻³. I-square: variation in estimated effects attributable to heterogeneity. D+L (Der Simonian and Laird method): pooled estimate of all studies. The mixed linear regression models were adjusted for: age, age squared, height, sex, body mass index, highest educational level, and smoking status at second spirometry; negative estimates indicated lower lung function with increasing exposure. ES: effect size.

FIGURE 3

Forest plot displaying the study-specific mixed linear regression model estimates of the association of NO₂ with level of forced expiratory volume in 1 s (FEV₁; in mL) in participants stratified as not obese (body mass index (BMI) <30 kg·m⁻²). NO2_1 indicates NO₂ measured at time of ESCAPE. Associations with lung function measures are presented as increments in NO₂ per 10 μg·m⁻³. I-square: variation in estimated effects attributable to heterogeneity. D+L (Der Simonian and Laird method): pooled estimate of all studies. The mixed linear regression models were adjusted for: age, age squared, height, sex, BMI, highest educational level, and smoking status at second spirometry; negative estimates indicated lower lung function with increasing exposure. p-value for heterogeneity, obese versus non-obese: 0.098 for FEV₁. ES: effect size.

FIGURE 4

Forest plot displaying the study-specific mixed linear regression model estimates of the association of NO₂ with level of forced expiratory volume in 1 s (FEV₁; in mL) in obese participants (body mass index (BMI) ≥30 kg·m⁻²). NO₂_1 indicates NO₂ measured at time of ESCAPE. Associations with lung function measures are presented as increments in NO₂ per 10 μg·m⁻³. I-square: variation in estimated effects attributable to heterogeneity. D+L (Der Simonian and Laird method): pooled estimate of all studies. The mixed linear regression models were adjusted for: age, age squared, height, sex, BMI, highest educational level, and smoking status at second spirometry; negative estimates indicated lower lung function with increasing exposure. p-value for heterogeneity, obese versus non-obese: 0.098 for FEV₁. ES: effect size.