Reduced oxygen affects human organs, conceptual artwork

Conceptual artwork illustrating how humans may evolve in a future where oxygen levels decrease in the atmosphere. Close-up view of a section of the ureter in the urinary system. In this scenario, bacteria now produce oxygen from nitrite, a compound produced from nitrate which is found in urine. Oxygen is picked up by red blood cells who exchange it for the waste gas carbon dioxide. This image forms part of a project "Below 12" which is a speculative scenario where human beings have synthetically engineered their organs to adapt to an oxygen-depleted atmosphere, as deforestation, desertification and population over-growth are contributing to a fall in the long-term loss of oxygen sources. The lowest concentration of oxygen recorded in a populated area is 12%. High levels of nitrites in urine today (nitrituria) can often indicate the presence of unwanted bacteria which can cause urinary tract infections.