It’s something we’ve all experienced: a cough that wakes you up in the middle of the night or turns a concert into a living nightmare because it simply won’t stop. Despite the inconvenience of it, there is a reason why we cough: it clears foreign particles from our airways. These particles and chemical substances irritate the mucous membranes in the airways, which triggers a reflex: coughing. Air is expelled via the airways at high pressure, with the flow of air reaching speeds of up to 100 km/h as it removes the foreign particles. It’s like a vacuum cleaner, only in reverse.