Inhalers are mainly used to treat two conditions: asthma and chronic obstructive pulmonary disease, or COPD. And there are two main types: preventative inhalers and rescue inhalers. Preventative inhalers can be used every day to control symptoms, while rescue inhalers are great in an emergency. So, how do they work? Anna Rothschild explains the science behind these simple yet powerful devices. Directed by Max Zaglotskyi, Anna Sai, Darvideo Animation Studio, narrated by Pen-Pen Chen].