Background: Nitrogen dioxide (NO2), a ubiquitous atmospheric pollutant, may enhance the asthmatic response to allergens through eosinophilic activation in the airways. However, the effect of NO2 on inflammation without allergen exposure is poorly studied.
Objectives: We investigated whether repeated peaks of NO2, at various realistic concentrations, induce changes in airway inflammation in asthmatics.
Methods: Nineteen nonsmokers with asthma were exposed at rest in a double-blind, crossover study, in randomized order, to 200 ppb NO2, 600 ppb NO2, or clean air once for 30 min on day 1 and twice for 30 min on day 2. The three series of exposures were separated by 2 weeks. The inflammatory response in sputum was measured 6 hr (day 1), 32 hr (day 2), and 48 hr (day 3) after the first exposure, and compared with baseline values measured twice 10–30 days before the first exposure.
Results: Compared with baseline measurements, the percentage of eosinophils in sputum increased by 57% after exposure to 600 ppb NO2 (p = 0.003) but did not change significantly after exposure to 200 ppb. The slope of the association between the percentage of eosinophils and NO2 exposure level was significant (p = 0.04). Eosinophil cationic protein in sputum was highly correlated with eosinophil count and increased significantly after exposure to 600 ppb NO2 (p = 0.001). Lung function, which was assessed daily, was not affected by NO2 exposure.
Conclusions: We observed that repeated peak exposures of NO2 performed without allergen exposure were associated with airway eosinophilic inflammation in asthmatics in a dose-related manner.
1Service des Etudes Médicales (SEM), EDF, Levallois-Perret, France; 2Service de Pneumologie A, Clinical Center of Investigation, Inserm U700, Bichat Hospital, Université Paris Diderot, DHU FIRE, Paris, France; 3Laboratoire de Biochimie, Bichat Hospital, Paris, France; 4Service de biostatistiques et épidémiologie, Gustave Roussy, Villejuif, France; 5Department of Physiology, Bichat Hospital, Paris, France; 6Department of Preventive Medicine, Keck School of Medicine of the University of Southern California, Los Angeles, Los Angeles, California, USA; 7Center for Research & Innovation in Gas and New Energy Sources, CRIGEN, GDF SUEZ, St-Denis, France
Recommended Citation:
Véronique Ezratty,1 Gaëlle Guillossou,1 Catherine Neukirch,et al. Repeated Nitrogen Dioxide Exposures and Eosinophilic Airway Inflammation in Asthmatics: A Randomized Crossover Study[J]. Environmental Health Perspectives,2014-01-01,Volume 122(Issue 8):850