Chronic Obstructive Pulmonary Disease (COPD) affects up to 20% of VA patients and is associated with poor health-related quality of life, frequent exacerbations, and disability. Physical activity (PA) is recommended for COPD patients, however PA may be affected by exacerbations and worsening respiratory symptoms triggered by environmental factors such as air pollution and changes in temperature. Increased use of short acting beta- agonist bronchodilator use may reflect transient worsening symptoms in the setting of an acute environmental exposure, a mild exacerbation, or the beginning of a moderate or severe exacerbation. A recently developed global positioning system (GPS)-enabled inhaler permits monitoring of both location and timing of bronchodilator use. Measuring increased beta-agonist use with the GPS-enabled inhaler is a novel method to measure mild exacerbations and will allow a better understanding of environmental factors that worsen COPD and interfere with PA. The study specific aims are: Aim 1: To capture worsening respiratory symptoms and mild exacerbations with a global positioning system (GPS)-enabled short-acting beta-agonist (SABA) inhaler device. Aim 2: To characterize PA in patients with COPD using pedometers and a Physical Activity Checklist. Aim 3: To examine whether environmental triggers (air pollution, temperature, relative humidity) are linked to mild exacerbations as measured by GPS-enabled SABA inhaler device. The proposed study will be a longitudinal observational study of 40 Veterans with moderate to severe COPD. Participants diagnosed with COPD from the VA Puget Sound Health Care System will be asked to participate if they have an FEV1/FVC between 0.3 and 0.7 on spirometry and are using a short-acting bronchodilator (e.g., albuterol) delivered by metered-dose inhaler (MDI). The GPS-enabled monitoring device will be placed on top of the patient's MDI canister to record the time and location of MDI use. Participants will be followed for a total of 12 weeks. Data ascertained from the study will include daily measurements of inhaler use (time, location), daily movements (GPS monitoring every 30 minutes), and daily pedometer measurements of steps taken. Patients will have monthly study visits to download GPS and pedometer data and to fill out questionnaires about history of exacerbations, the last 7 days of PA, and chronic respiratory symptoms. Additionally, patients will be asked to fill out a 7-day activity diary to collect more detailed information about their daily routines. GPS data on patient location throughout the day and place where the MDI was actuated will be linked to data on Seattle air pollution from the Environmental Protection Agency (EPA) and meteorology data from the National Oceanic and Atmospheric Administration (NOAA). Data analysis will focus on descriptive statistics for each measure, characterizing increased short-acting beta agonist use, and measuring patient compliance with the GPS-enabled MDI, pedometer, and activity diary. The results of this study will be used to inform a Merit Review proposal to evaluate the impact of exacerbations on a PA intervention for COPD patients and the contribution of environmental triggers to these exacerbations. Specifically the goals of the future study would be to: 1) determine the factors (including mild exacerbations measured using GPS-enabled MDI use) associated with decreased participation in physical activity, exercise programs, and pulmonary rehabilitation, and 2) to develop an intervention to increase physical activity in COPD that incorporates strategies to prevent exacerbations including avoiding environmental triggers, and maintaining physical activity after experiencing exacerbations. By better understanding the effect of mild exacerbations on PA, as well as the potential environmental triggers of mild exacerbations, we can provide patients and their providers with more appropriate advice about how to reduce exacerbations and develop and sustain PA at home.