An automatic data driven blood gas monitoring program, calculated the arterial/Alveolar (a/A) oxygen partial pressure ratio for all (approx. 40,000) arterial blood gas samples drawn between 4/87 and 2/88. Patients with an a/A ratio ≤ 0.2 were examined to determine if they had Adult Respiratory Distress Syndrome (ARDS). To determine if ARDS was linked to the inspired oxygen fraction (FiO2), or pressure exposure, a computer exposure monitoring program evaluated each patient's total exposure to FiO2, positive end expiratory pressure (PEEP), and peak inspiratory pressure (Peak) from the date of hospital admission until 24 hours after their a/A ratio was ≤ 0.2. of the 6,000 patients originally screened, 372 patients were identified by the program (6.2%), 44 (0.7%) were determined to have ARDS. A comparison of ARDS survivors with non-survivors showed that survivors spent a significantly (p < 0.05) shorter percentage of time on ventilators with FiO2 ≥ 60% (22.2% vs.59.9%), PEEP ≥ 10 cm H2O (25.7% vs.50.1%) and Peak ≥ 55 cm H2O (2.2% vs.7.2%) with no difference in their Acute Physiologic Score (14.5 vs.13.5). These findings suggest that oxygen and pressure exposure are associated with the development of ARDS.