Monitoring of lung function in at-risk populations enables the identification of individuals with excessive decline of lung function. The spirometry test of forced expiratory volume in one second (FEV1) is the measure best suited for monitoring changes in lung function over time. An excessive decline in FEV1 over several years can indicate development of lung disease and has been shown to be associated with increased respiratory morbidity, loss of productivity at an earlier age, and increased mortality. The Spirometry Longitudinal Data Analysis (SPIROLA) software is an integrated visual and quantitative tool to aid in monitoring lung function in individuals participating in spirometry-based health monitoring programs. To ensure that individuals with excessive decline in lung function can be identified accurately and in timely manner, it is important to maintain acceptable precision of the longitudinal spirometry data. In order to maintain data precision at an acceptable level, SPIROLA enables the user to monitor longitudinal data precision and spirometry quality grades for the monitoring program, this provides also a basis on which to determine an appropriate limit of longitudinal decline in individuals. SPIROLA may help to preserve lung function through identification of excessive decline followed by appropriate intervention. The intervention function helps the user to obtain information on potential risk factors, and plan, record, and evaluate the effect of intervention strategies. SPIROLA provides the following functions: For an individual: 1. It monitors the level of FEV1 and FVC in relation to criteria for assessment of cross-sectional data: the lower limit of normal (LLN) (i.e., the lower 5th percentile) and the lower 0.1th percentile (approximately comparable to 60% predicted). 2. It monitors FEV1 change over time in relation to criteria for assessment of longitudinal changes: the limit of longitudinal decline (LLD). 3. It provides interpretation of the rate of FEV1 decline and data variability in an individual's summary report and suggests actions to prevent further excessive loss. 4. It enables to plan, record, and evaluate intervention measures. For a group of individuals: 1. It monitors longitudinal data precision using the pair-wise estimate of within-person variation Sp (absolute) or Sr (relative). 2. It monitors group means for observed, predicted and z-score for FEV1 and FVC to enable the user to identify time-related changes taking place at a group level. 3. It monitors statistics on the spirometry quality grades, as provided by a spirometry system, as a percentage of testing sessions that do not meet the 2005 ATS/ERS criteria for acceptability and repeatability, overall and by individual technicians. 4. It provides statistics and lists of individuals whose lung function tests fall below the LLN and whose rate of lung function decline and variability may be excessive.