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Continuous positive airway pressure (CPAP) is a method of respiratory support used around the world to treat children with lower respiratory tract infections (LRTI) (WHO, 2016, Oxygen Therapy for Children, World Health Organization, Geneva, Switzerland, Report). Bubble continuous positive airway pressure (bCPAP) is an effective form of CPAP that is currently used in both high- and low-resource countries. Low-cost, modified bCPAP devices have been designed as an ideal form of CPAP in low-resource areas (Bjorklund, A. R., Mpora, B. O., Steiner, M. E., Fischer, G., Davey, C. S., and Slusher, T. M., 2018, “Use of a Modified Bubble Continuous Positive Airway Pressure (bCPAP) Device for Children in Respiratory Distress in Low- and Middle-Income Countries: A Safety Study,” Paediatr. Int. Child Health, 39(3), pp. 1–8). However, patients in low-resource settings undergoing bCPAP treatment are often given pure oxygen, which has been linked to retinopathy of prematurity, cardiovascular complications, and patient mortality (Rodgers, J. L., Iyer, D., Rodgers, L. E., Vanthenapalli, S., and Panguluri, S. K., 2019, “Impact of Hyperoxia on Cardiac Pathophysiology,” J. Cell. Physiol., 234(8), pp. 1–9; Ramgopal, S., Dezfulian, C., Hickey, R. W., Au, A. K., Venkataraman, S., Clark, R. S. B., and Horvat, C. M., 2019, “Association of Severe Hyperoxemia Events and Mortality Among Patients Admitted to a Pediatric Intensive Care Unit,” JAMA Network Open, 2(8), p. e199812). This problem is typically avoided by using commercial oxygen blenders, which can titrate down the concentration of oxygen delivered to the minimum needed; however, these blenders can cost nearly 1000 USD and are almost always unavailable in low-resource settings. The lack of available low-cost oxygen blenders compatible with modified bCPAP circuits creates a barrier for low-resource hospitals to be able to provide blended oxygen to patients. There is a need for a low-cost oxygen blender for use in low-resource settings. We propose a passive oxygen blender that operates via entrainment of atmospheric air. The device can easily be assembled in low-resource areas using a 22 gauge hypodermic needle, two 3 cc syringes, tape or super glue, and the materials required for bCPAP—for approximately 1.40 USD per device. The blender has not been clinically tested yet, but can achieve oxygen concentrations as low as 60% with bCPAP levels of 5 cm H2O (490 Pa) when used in a standard bCPAP circuit without a patient.