Danger Dust

The science of why you cough, when it’s good for you and when it’s not

The cough reflex can also be triggered by a range of chemicals, like those contained in cigarette or wildfire smoke, as well as toxic gases and the stomach juice that can sometimes backtrack into the respiratory tract during an episode of acid reflux. When you cough, “your airway, because it’s so important to you, is protecting itself against the damage associated with aspiration of oral gastric contents or noxious materials,” says Shiloh.

Receptors on one of several types of neurons that snake through the lining of the respiratory tract trigger the cough reflex. Some neurons detect chemical stimuli and others are mechanosensory, detecting pressure from something like a bit of food, another foreign object or a liquid like Hegland’s coffee.

When activated, the neurons send signals to the base of the brain — the brainstem — to initiate a cough, which briefly rejiggers normal breathing activity into three quick, coordinated phases. First, a sharp inhale. Then, closing of the space between the vocal cords, called the glottis, and contraction of abdominal and ribcage muscles to build pressure in the chest. Finally, opening of the glottis to release a sudden burst of compressed air.