Final answer:
Respiratory infections, viral or bacterial infections, environmental pollutants, and smoking are primary causes for an acute exacerbation of COPD.
Step-by-step explanation:
Acute exacerbations of chronic obstructive pulmonary disease (COPD) can be caused by several factors. Some primary causes include respiratory infections such as pneumonia, viral or bacterial infections, and exposure to environmental pollutants or irritants. Smoking tobacco is also a major cause of COPD exacerbations.