1. Initiation of exercise - As we begin to exercise, our breathing rate will slowly increase as our body would be require to use more oxygen or the demand for oxygen increases .
2. Moderate exercise - As stated above for the initiation of exercise, the oxygen demand would increase as the intensity of the exercise increases and in this case, moderate exercise would lead to a significant increase in our breathing rate.
3.Asthma attack - When a person experiences an asthma attack, the airways would be swollen/inflamed which would lead to coughing or most commonly difficulty in breathing.
4. Abrupt ascent into high altitudes - When we experience an abrupt ascent into high altitudes, our breathing rate will increase as the oxygen decreases in high altitude so our body would then require an adequate amount of oxygen as we experience trouble in breathing.
5. Pneumonia - In some severe cases of pneumonia, we may be required to use a ventilator in order for our lungs to heal as we lack oxygen and as we have trouble in breathing. There is also swelling/inflammation as well as mucus which makes it hard for air to pass through.
6. Paralysis of phrenic nerve - During paralysis of the phrenic nerve, our diaphragm would be damaged or weakened which would lead to problems in breathing as well as for voluntary breathing.
7. Severe tuberculosis with resulting lung scar tissue - Individuals who experience Severe tuberculosis with resulting lung scar tissue would experience inflammation in the airways which would also lead to problems in the reception of oxygen for the body and would probably also cause death.
8. Severe anemia - If a person has severe anemia, he/she would experience an abnormally fast heartbeat or heart failure.
9. Advanced COPD - When a person has an advanced chronic obstructive pulmonary disease or COPD, exacerbations may occur or you would often feel out of breath and energy. Your lungs would also end up damaged compared to before even if you recover.
10. Advanced pregnancy - If a woman is in this stage(advanced pregnancy) It is common to have shortness of breath but the chances of it worsening should lead her to consult her doctor as this may not only be caused by pregnancy alone as they are more at risk for complications.