First, it's important to understand what respiratory failure is. Respiratory failure is a syndrome, not a disease, meaning it can result from many causes. For instance, airway obstruction, lung tissue pathology, diseases of the pulmonary vessels, and diseases of the thorax and pleura, as well as neuromuscular diseases, can all lead to impaired ventilation or gas exchange in the lungs. This impairment makes it impossible for the body to maintain adequate gas exchange even in a resting state, resulting in hypoxemia, with or without hypercapnia, which is referred to as respiratory failure. Therefore, there are many causes of respiratory failure, and some diseases are indeed contagious, such as SARS, H1N1, and H3N2. However, other causes, such as tumors or pulmonary embolism, are generally not contagious.