This document provides standardized guidelines for spirometry, focusing on the standardization of lung function testing. It outlines the definitions, equipment requirements, test procedures, and quality control measures for spirometry, including the measurement of forced vital capacity (FVC), forced expiratory volume in one second (FEV1), and other derived indices. The document emphasizes the importance of accurate and consistent spirometry to ensure reliable results for diagnosing respiratory conditions. It includes detailed procedures for test initiation and termination, evaluation of test quality, and the selection of acceptable test results. The guidelines also address the use of flow-volume loops, reversibility testing, and the standardization of equipment and test parameters. The document aims to unify the standards of the American Thoracic Society (ATS) and European Respiratory Society (ERS) to ensure consistent and accurate spirometry across different settings. Key aspects include the calibration of spirometers, the accuracy of measurements, and the importance of proper technique and patient cooperation. The guidelines also provide recommendations for handling special cases, such as children, patients with neuromuscular disease, and those with airflow limitation. The document emphasizes the need for regular calibration, quality control, and proper interpretation of test results to ensure the reliability and validity of spirometry in clinical practice.This document provides standardized guidelines for spirometry, focusing on the standardization of lung function testing. It outlines the definitions, equipment requirements, test procedures, and quality control measures for spirometry, including the measurement of forced vital capacity (FVC), forced expiratory volume in one second (FEV1), and other derived indices. The document emphasizes the importance of accurate and consistent spirometry to ensure reliable results for diagnosing respiratory conditions. It includes detailed procedures for test initiation and termination, evaluation of test quality, and the selection of acceptable test results. The guidelines also address the use of flow-volume loops, reversibility testing, and the standardization of equipment and test parameters. The document aims to unify the standards of the American Thoracic Society (ATS) and European Respiratory Society (ERS) to ensure consistent and accurate spirometry across different settings. Key aspects include the calibration of spirometers, the accuracy of measurements, and the importance of proper technique and patient cooperation. The guidelines also provide recommendations for handling special cases, such as children, patients with neuromuscular disease, and those with airflow limitation. The document emphasizes the need for regular calibration, quality control, and proper interpretation of test results to ensure the reliability and validity of spirometry in clinical practice.