This study is testing two inhalers, **BDA MDI** (budesonide/albuterol) and **AS MDI** (albuterol sulfate), in teens aged 12 to under 18 who have asthma. Both inhalers will be used when needed over a year to see how they help prevent severe asthma attacks. Participants will be randomly assigned to one of the two inhalers and continue their regular asthma treatments. The study will last about a year and includes three parts: a screening period (7 to 28 days), a treatment period (52 weeks), and a follow-up period (7 to 14 days). There's also a special sub-study with one extra visit.

• The study lasts for about a year and includes several visits.
• Participants continue their regular asthma treatments during the study.
• **Important**: Participants must be able to use an inhaler correctly and meet specific health criteria.

This study is not for those with very severe asthma or other serious health issues. Participants and their caregivers must agree to follow the study rules and provide consent.