What is more serious of a disease, lower respiratory tract infections or upper respiratory tract infections?

Lower respiratory: Upper respiratory infections involve upper airways such as throat, nasal cavity, paranasal sinuses, eustachian tubes, trachea as, nd bronchi. When the disease process in the bronchi, or bronchitis, continues, it could begin to involve lower airways in the lung tissues, which is then more advanced lower respiratory infections or pneumonia.

Lower: Upper respiratory tract infections are colds, rhinitis, pharyngitis, sinusitis and are usually caused by viruses although can also be caused by various bacteria. Lower respiratory infections are bronchitis and pneumonia also caused by viruses but more than uri's are caused by bacteria and can be more severe and even life threatening.