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Environ Health Perspect. 2014 Aug;122(8):850-5. doi: 10.1289/ehp.1307240. Epub 2014 Apr 18.

Repeated nitrogen dioxide exposures and eosinophilic airway inflammation in asthmatics: a randomized crossover study.

Author information

1
Service des Etudes Médicales (SEM), EDF, Levallois-Perret, France.

Abstract

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.

PMID:
24747297
PMCID:
PMC4123022
DOI:
10.1289/ehp.1307240
[Indexed for MEDLINE]
Free PMC Article

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