Shortness of breath has many causes affecting either the breathing passages and lungs or the heart or blood vessels. An average 150-pound (70 kilogram) adult will breath at an average rate of 14 breaths per minute at rest. Excessively rapid breathing is referred to as hyperventilation. Shortness of breath is also referred to as dyspnea. Doctors will further classify dyspnea as either occurring at rest or being associated with activity or exercise. They will also want to know if the dyspnea occurs gradually or all of a sudden. Each of these symptoms help to detect the precise cause of the shortness of breath. Causes of shortness of breath include asthma, bronchitis, pneumonia, pneumothorax, anemia, lung cancer, inhalation injury, pulmonary embolism, high altitude with lower oxygen levels, congestive heart failure, allergic reaction, anaphylaxis, subglottic stenosis, interstitial lung disease, obesity, tuberculosis, emphysema, pulmonary artery hypertension, rib fracture, and aerobic exercise. Shortness of breath can be associated with symptoms of chest pain, pain with inspiration (pleurisy), dizziness, fainting, cough, wheezing, bloody sputum, neck pain, and chest injury.