Non-invasive intratracheal instillation is a technique used to deliver substances directly into the lungs without surgical intervention. The protocol involves anesthetizing the subject (e.g., mouse or rat), positioning it at a slight incline, using a specialized intubation device or catheter to insert into the trachea, instilling the liquid substance gently, and monitoring post-procedure recovery. This method is commonly used for pulmonary research, drug delivery, and toxicology studies.