When a person has an asthma attack, a chemical molecule, acetylcholine, normally responsible for maintaining muscle tone of the airways, also contributes to the contractions in asthma attacks. Traditional asthma medication blocks the molecule by preventing it to bind to the receptors. THC likewise does the same. It does not stop the molecule from binding, it prevents acetylcholine from being released. When THC is released through a vaporizer, it has almost immediate bronchial dilation effects without the risk of harmful smoke.