Inflammation of the lungs and bronchial tubes are also common causes of shortness of breath, as is injury to the respiratory tract caused by smoking or other toxins. Shortness of breath may occur with injury to the lungs, such as a collapsed lung (pneumothorax).
In the United States, pea soup without qualification usually means a perfectly smooth puree. Split Pea Soup is a slightly thinner soup with visible peas, pieces of ham or other pork, and vegetables (most commonly carrots) and is usually made from dried, green split peas.
Split peas are field peas, which are a variety of yellow or green peas grown specifically for drying. When these peas are hulled and then split in half along the natural seam, they become split peas, which encourages faster cooking and eliminates the need to presoak.