Triggers or stresses on the body activate the "fight or flight" response, causing hyperventilation. Hyperventilation increases the amount of air breathed.

Low levels of carbon dioxide can cause chemical changes in the membranes of mast cells, causing histamine production to increase, leading to inflammation and extra mucus is produced.

Carbon dioxide levels in the blood stream falls to levels that cause the smooth muscle to constrict. Each of these factors cause the airways to constrict, making breathing difficult.

Overbreathing also leads to increased inhalation of allergies.

Hyperventilation cools and dries out sensitive airways, irritating and inflaming them

Hyperventilation also leads to low levels of carbon dioxide - a condition known as "Respiratory Alkalosis"

Low levels of carbon dioxide cause smooth muscle to spasm, giving the feeling of chest tightness.

Low levels of carbon dioxide stimulate mast cells to produce histamine. This causes inflammation and constriction in the airways The dry irritated airways produce extra mucus in an effort to lubricate themselves

All these things lead to difficulty with breathing (asthma)

Having difficulty with breathing is very stressful and it is normal to breath deeper or harder in an effort to try to correct the problem. This causes further respiratory alkalosis, leading to more asthma

Reliever medication is normally used at this point. These drugs are smooth muscle relaxants and allow the airways to open. Many of them are also adrenaline-based which act as a stimulant, increasing the breathing rate further

Excessive reliever usage usually leads to the taking of steroid medication. Steroid medication suppresses the immune system, resulting in more virus's and infections being caught. Illness is a stress on the body to which the body responds by hyperventilating, and so we are back at the beginning again