Though the military population does go through robust medical screenings, altitude exposure can significantly worsen many preexisting medical conditions. Current recommendations vary greatly depending on the specific condition, with minimal effect from altitude sojourns to strict contraindications with altitude exposures. A non-exhaustive list includes asthma, cardiovascular disease, pulmonary disease, hemoglobinopathies (including sickle-cell trait), pulmonary hypertension, obstructive/central sleep apnea and medications causing respiratory depression.4,6- See table of comorbidities and recommendations before altitude expositions.