The purpose of this research study is to determine the effect of the environment on six-minute walk test performance in individuals with chronic obstructive pulmonary disease due to alpha-1 antitrypsin deficiency. The aim of the study is to determine the environmental impact on physical performance in this population to determine if any factors influence quality of life. This study was developed to evaluate the efficacy of the using the indoor six-minute walk test to determine eligibility for ambulatory oxygen therapy.