The respiratory system is particularly sensitive to air pollution. The lungs must bring in large quantities of air (over 400 million litres in a lifetime) in order to supply sufficient oxygen to the blood system. Air pollutants, such as ground-level ozone and particulate matter can injure the lungs directly. These pollutants may also trigger inflammation in the lungs that can affect the heart and blood vessels. The air pollutants may also enter the blood and can affect other organs elsewhere in the body.