What factor can influence the accuracy of spirometry measurements?

Calibration of the spirometer is crucial for ensuring accurate measurements because a malfunctioning or improperly adjusted device can yield erroneous results. Regular calibration helps maintain the precision of volume and flow measurements, which are essential for evaluating lung function.

The humidity of the testing environment can also affect the results. For instance, high humidity can lead to an increase in the resistance of the airflow through the spirometer, which can distort readings. Therefore, maintaining a controlled environment is important for consistent and reliable spirometry results.

Additionally, a patient's previous lung function test results provide critical context for interpreting current measurements. Variations between tests may indicate changes in lung function due to various factors such as disease progression, treatment effects, or lifestyle changes.

All these factors—calibration, environmental conditions, and historical data—collectively influence the accuracy of spirometry measurements, making the comprehensive answer indicative of the multiple influences at play in ensuring reliable pulmonary function testing results.