A campaign to make people more aware of what to do if someone has an asthma attack started on Monday.
A recent poll found that although 93% of people knew asthma attacks could be fatal, only 50% knew what to do if they saw someone having one.
Asthma UK, the group behind the drive, want people to be taught to calm sufferers down, how to use an inhaler and when to call for an ambulance.
The Deadly Serious Campaign will spread their message with TV adverts.
The group want people with the condition, and people who care for them, to carry cards with written instructions on what to do if they have an attack.
There are 5.2m people in the UK with asthma, and 400,000 of them have such bad attacks they can't ask for help.
Spokeswoman Donna Covey said: "One in five households is affected by asthma so if you don't have asthma yourself, you will know someone who does."