Why does the colour of sputum of pneumonia patient is green?

The green color of sputum in pneumonia patients is primarily due to the presence of white blood cells, specifically neutrophils, which accumulate at the site of infection. These cells contain enzymes and proteins that can cause a greenish hue when they break down. Additionally, the presence of bacteria and the inflammatory response may further contribute to the discoloration. This green sputum often indicates a more severe infection or the presence of certain types of bacteria.