That's very tragic.
Unfortunately asthma can be like that, it is more dangerous than many people realise and can strike without much warning; although illness such as a common cold, flu or a chest infection can trigger an attack in asthma sufferers, bad attacks mostly happen without illness as it is usually caused by either allergy to pollen, dust or dustmites, increased pollution such as car fumes on hot days, stress or exertion. I suffer from it but not badly. A childhood friend of my brother's died of asthma when he was just 13.
My heart goes out to this young man's family and friends.
------------------
Time is an illusion. Lunchtime doubly so.
Epona of The Laughing Hyenas