International Rhinologic Society Rhinology 0300-0729 2026 06 23 The effect of large air pollution exposure on chronic rhinitis EN Christophe Abi Zeid Daou Department of Otolaryngology and Head and Neck Surgery, American University of Beirut Medical Center, Beirut, Lebanon Ibana Carapiperis Department of Otolaryngology and Head and Neck Surgery, American University of Beirut Medical Center, Beirut, Lebanon Jusitn Ghadieh Department of Medicine, American University of Beirut, Beirut, Lebanon Omar Abou Hosn Department of Otolaryngology and Head and Neck Surgery, American University of Beirut Medical Center, Beirut, Lebanon Zeina Korban Department of Otolaryngology and Head and Neck Surgery, American University of Beirut Medical Center, Beirut, Lebanon Chadi A. Makary Department of Otolaryngology and Head and Neck Surgery, West Virginia University, United States of America Journal Article 3480 10.4193/Rhin25.293 On August 4th, 2020, Beirut witnessed the largest non-nuclear explosion in modern history. The explosion resulted in the release of large amounts of gases and particulate matters (PM) including ammonia and nitrogen oxides (NOx), as well as pure oxygen (O2) (1). NO2 conversion into nitric and nitrous acids has been shown to damage the alveolar structure in distal airways (2). The goal of this study is to investigate the early and late, subjective and objective, effects of the explosion and particulate matter exposure on the upper airway, specifically chronic rhinitis.