The nose and throat is our body's first line of defence in the fight against pollutants contained in the air we breathe. Their job is to purify and humidify the air before it enters more sensitive parts of our respiratory system and does us real damage.

A central part of this defence mechanism is a layer of tiny hair-shaped structures, called cilia, inside our respiratory tract and a thin membrane of mucous that covers them. Airborne pollutants, such as viruses and bacteria, are captured by this sticky mucous membrane and removed from the air. The tiny cilia whip back and forth many times per second to transport the mucous and its freight towards our throats. It is then swallowed and any pollutants destroyed by our digestive system.

If the air we are breathing in is below 40%RH (relative humidity) over a prolonged period of time, this mucous membrane layer dries out. This can cause damage to the cilia, inhibits our ability to filter pollutants from the air we breathe and leave us susceptible to airborne infection.

Optimal humidity aids mucociliary clearance

Mucous membranes in our respiratory tract trap airborne pollutants and tiny cilia transport them to our pharynx and digestive system, where they are destroyed.

Low humidity dries our mucous membranes leaving us prone to airborne infection

In low humidity environments below 40%RH our mucous membranes dry and this "mucociliary clearance" process is impaired. This leaves us more susceptible to airborne infections, like the flu or common cold.

Scientific studies showing how dry air affects our immune system