Final answer:
Spirometry is the tool used to measure air filter restriction, which is useful in diagnosing different types of lung diseases by measuring the FEV1/FVC ratio.
Step-by-step explanation:
To measure the air filter restriction, particularly in the context of diagnosing lung diseases, spirometry is the tool commonly used. Spirometry assesses the rate at which air can be expelled from the lungs and is effective in diagnosing restrictive lung diseases, where the Forced Vital Capacity (FVC) is reduced but the airways are not obstructed. This allows a person to expel air at a relatively normal rate. In contrast, obstructive lung disease is characterized by a lower FEV1/FVC ratio, indicating slower exhalation and reduced FVC due to airway obstruction. Therefore, by measuring the Forced Expiratory Volume in one second (FEV1) and the FVC, healthcare providers can determine the presence and type of lung disease. The ratio of FEV1 to FVC is critical; a lower ratio (less than 69 percent) suggests obstructive lung disease, whereas a higher ratio (around 88 to 90 percent) suggests restrictive lung disease.