Asthma affects nearly 25 million Americans. It’s a chronic, inflammatory disease of the lungs and airways that makes it difficult to breathe at times. While there is no cure for asthma, it can help to avoid your triggers. An asthma trigger is something that causes your asthma to get worse. When you’re exposed to it, you can get an asthma attack, flare-up, or episode—a sudden worsening of your asthma symptoms.