About one in six New Zealanders has asthma, while one in four New Zealand children has the respiratory disease that causes symptoms including coughing, wheezing and shortness of breath.
That gives us one of the highest asthma rates in the world. There's currently no cure for it so most sufferers try to avoid triggers like dust and pollen, and use steroid-based treatments.
But if you have an asthma attack, when the airways in the lungs become irritated and swollen, you'll probably need to puff on an asthma reliever or a bronchodilator.
John Ashton of the Department of Pharmacology & Toxicology at the Otago School of Medical Sciences looks at how the popular asthma reliever Ventolin works.