The effects of aging on the respiratory system are similar to those that occur in other organs: maximum function gradually declines. Age-related changes in the lungs include
Decreases in peak airflow (how quickly someone can exhale) and exchange of carbon dioxide and oxygen Exchanging Oxygen and Carbon Dioxide The primary function of the respiratory system is to take in oxygen and eliminate carbon dioxide. Inhaled oxygen enters the lungs and reaches the alveoli. The layers of cells lining the alveoli... read more
Decreases in measures of lung function Pulmonary Function Testing (PFT) Pulmonary function tests measure the lungs' capacity to hold air, to move air in and out, and to absorb oxygen. Pulmonary function tests are better at detecting the general type and severity... read more
such as vital capacity (the maximum amount of air that can be breathed out following a maximum inhalation)Decline in the effectiveness of lung defense mechanisms Defense Mechanisms of the Respiratory System The average person who is moderately active during the daytime breathes about 20,000 liters (more than 5,000 gallons) of air every 24 hours. Inevitably, this air (which would weigh more than... read more
(See also Overview of the Respiratory System Overview of the Respiratory System To sustain life, the body must produce sufficient energy. Energy is produced by burning molecules in food, which is done by the process of oxidation (whereby food molecules are combined with... read more .)
In healthy people, these age-related changes seldom lead to symptoms. These changes contribute somewhat to an older person's reduced ability to do vigorous exercise, especially intense aerobic exercise, such as running, biking, and mountain climbing. However, age-related decreases in heart function may be a more important cause of such limitations.
Older people are at higher risk of developing pneumonia Overview of Pneumonia Pneumonia is an infection of the small air sacs of the lungs (alveoli) and the tissues around them. Pneumonia is one of the most common causes of death worldwide. Often, pneumonia is the final... read more 
after bacterial or viral infections. Thus, vaccines for respiratory infections such as influenza Influenza (Flu) Influenza (flu) is a viral infection of the lungs and airways with one of the influenza viruses. It causes a fever, runny nose, sore throat, cough, headache, muscle aches (myalgias), and a general... read more and pneumococcal pneumonia Pneumococcal Infections Pneumococcal infections are caused by the gram-positive, sphere-shaped (coccal) bacteria (see figure How Bacteria Shape Up) Streptococcus pneumoniae (pneumococci). These bacteria commonly... read more are particularly important for older people.
Importantly, age-related changes in the lungs are compounded by the effects of heart and lung diseases, especially those caused by the destructive effects of smoking.
