About respiratory failure, the following is false:
Type I or Hypoxemic respiratory failure is characterized by PaO2 <60 mm Hg with a normal or low arterial carbon dioxide tension. 

Causes:- Pneumonia, ARDS, pulmonary embolism, pulmonary edema 

Type II or Hypercapnic respiratory failure is characterized by a PaCO2 >50 mm Hg. May be associated with hypoxemia. 

Causes:- Drug overdose, neuromuscular disease, chest wall abnormalities, and severe airway disorders (eg, asthma and COPD) 

Type III failure involves post-operative atelectasis.
Type IV failure is due to decreased blood flow to respiratory muscles.
Type III failure involves post-operative atelectasis
Type II failure doesn’t have fall in paO2 (hypoxia)
Type I failure involves hypoxia (paO2)
Pneumonia usually presents with type I respiratory failure