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Inflammatory response in humans exposed to 2.0 ppm nitrogen dioxide
R B Devlin1, D P Horstman, T R Gerrity
1Environmental Protection Agency, National Health and Environmental Effects Research Laboratory, Mail Drop 58D, Research Triangle Park, NC 27711, USA. devlin.robert@epamail.epa.gov
Inhalation Toxicology
|June 24, 1999
Summary
Exposure to nitrogen dioxide (NO2) at 2.0 ppm during exercise caused bronchial inflammation and impaired alveolar macrophage function in healthy adults. Lung function tests showed minor obstructive changes, suggesting NO2
Area of Science:
- Environmental Health
- Pulmonary Medicine
- Toxicology
Background:
- Nitrogen dioxide (NO2) is a prevalent indoor air pollutant linked to respiratory issues in children.
- Previous human studies showed minimal lung inflammation from moderate NO2 exposure.
- The impact of NO2 during exercise on lung defenses remains unclear.
Purpose of the Study:
- To investigate the effects of moderate nitrogen dioxide (NO2) exposure during exercise on human respiratory health.
- To assess NO2-induced changes in bronchial and alveolar inflammation and immune cell function.
- To evaluate alterations in lung function and susceptibility to viral infection.
Main Methods:
- Eight healthy volunteers were exposed to 2.0 ppm NO2 or filtered air for 4 hours with intermittent exercise.
- Bronchoalveolar lavage (BAL) was performed, separating bronchial (BL) and alveolar (BAL) samples.
- Assays included cell counts, inflammatory mediators (IL-6, IL-8), macrophage phagocytosis, superoxide production, and viral susceptibility.
- Lung function was assessed using spirometry and aerosol bolus recovery.
Main Results:
- NO2 exposure increased inflammatory cells (PMNs) and mediators (IL-6, IL-8) in bronchial washings.
- Alveolar macrophages showed reduced phagocytic capacity and superoxide production after NO2 exposure.
- No significant changes were observed in alveolar cells, soluble mediators, or viral susceptibility.
- Aerosol bolus recovery indicated small obstructive changes in the lungs post-NO2 exposure.
Conclusions:
- Moderate NO2 exposure during exercise induces bronchial inflammation and impairs alveolar macrophage immune function.
- These effects suggest a potential increase in susceptibility to respiratory infections.
- The findings highlight the subtle but significant impact of indoor air pollutants on lung health, even in healthy individuals.