Seasonal Oxidative Stress and Airway Reactivity in Rhinitis: Distinct Patterns in Allergic vs. Non-allergic...

Rhinitis is a common upper airway disorder, classified as either allergic rhinitis (AR) or non-allergic rhinitis (NAR). While the association between air pollution and AR airway diseases has been well documented, its specific effects on NAR remain poorly understood. This study aimed to evaluate the seasonal impact of air pollution on pulmonary function, oxidative stress biomarkers, and bronchial hyperresponsiveness in patients with AR, patients with NAR, and healthy controls.

In this prospective case-control study, 58 participants (23 AR, 22 NAR, 13 controls) were evaluated during periods of low pollution (summer) and high pollution (winter). Assessments included symptom questionnaires, pulmonary function tests, bronchial provocation tests (BPT), serum total antioxidant status (TAS), and total oxidative status.

In the high pollution period, the NAR group exhibited significantly lower TAS levels compared to summer (1.51±0.15, 1.60±0.2, P = 0.041), indicating an increased oxidative stress. A significant decrease in post-bronchodilator forced expiratory volume in 1 second (FEV)₁ was also observed in the NAR group, suggesting heightened airway reactivity. The AR group demonstrated a higher frequency of BPT reactivity. Pulmonary function declined across all groups in winter, with the greatest reduction observed in AR patients. Within-group analyses revealed seasonal reductions in both FEV₁ and post-BPT FEV₁ in AR and NAR groups.

Seasonal air pollution exerts phenotype-specific effects on oxidative stress and airway reactivity in rhinitis. AR patients exhibited increased bronchial hyperresponsiveness, whereas NAR individuals showed a marked decline in antioxidant capacity. These findings highlight the importance of phenotype-based monitoring and management during periods of high environmental exposure.