The airway epithelium. which lines the conducting airways. is central to the defense of the lungs against inhaled particulate matter and pathogens such as SARS-CoV-2. the virus that causes COVID-19. https://www.roneverhart.com/BRExhaust-2004-2006-Nissan-TITAN-5-6L-Direct-Fit-Replacement-Exhaust-System/