HBG2 and Cyanosis: Further, the biochemical effects of NO3− occur in the human body as follows: (a) NO3− is converted to NO2− under reducing conditions, (b) haemoglobin (Hb) combines with NO2− to form methemoglobin, (c) the effect of methemoglobin reduces the oxygen supply in red blood cells and drops the oxygen level in the body and (d) higher rate of methemoglobin formations (> 10%) leads to the blueish colouration of the skin, known as a blue-baby syndrome (cyanosis)4,32.