Pulmonary artery carries impure blood.

The pulmonary artery is the only artery that carries deoxygenated blood. It transports blood from the right ventricle of the heart to the lungs for oxygenation (pulmonary circulation). After receiving oxygen in the lungs, the blood returns to the heart via the pulmonary veins, which are the only veins carrying oxygenated blood. All other arteries carry oxygenated blood, and all other veins carry deoxygenated blood.