Commentary: quality of spirometry testing.

Spirometry is necessary for the diagnosis and monitoring of both obstructive and restrictive lung diseases. Today, the most rapidly growing health problem in the United States is chronic obstructive pulmonary disease (COPD). COPD is now the fourth most common cause of death and the only cause of death that is rising among the top ten causes. There is also an increasing prevalence of interstitial lung diseases. Both obstructive and interstitial lung diseases are identified and monitored by spirometry.