So more blood flows into our infected area as a result of this vassal dilation process. The increase in diameter of those blood vessels, that brings more blood as well as more wide blood cells. Now, what histamine also does is it increases the permeability of the nearby capillaries to water and that makes those capillaries leaky. And that's exactly why people that experience hay fever have a red nose as well as a leaky nose because the capillaries become more permeable to water and we have more blood flowing to this area. And that's exactly why it appears more red than usual because of the effect that histamine has on our body. So once again, tiny pollen, microscopic pollen particles enter the air passageways of our body our nasal canal, our trachea, the bronchi and the bronchioles.