The nose is our first line of defense.
This is because the mucus lining the nasal cavity produced by gland cells filters the air we breathe by trapping pollutants, micro-organisms, dust and other harmful particles.
With the help of cilia, this mucus is then moved to the back of the throat where it is either swallowed or coughed out.
During a common cold, flu or sinusitis, the mucus layer becomes thick causing nasal congestion and impairing the free movement of the cilia. This in turn leads to the slowing down of the Mucociliary Clearance System leading to blockage of the sinus outflow that increases the risk of upper respiratory tract infections.