Causes
An overly sensitive immune system makes your airways (bronchial tubes) become inflamed and swollen when you're exposed to certain triggers. Asthma triggers vary from person to person. Common asthma attack triggers include:
• Pollen, pets, mold and dust mites
• Upper respiratory infections
• Tobacco smoke
• Exercise
• Inhaling cold, dry air
• Gastroesophageal reflux disease (GERD)
For many people, asthma symptoms get worse with a respiratory infection such as a cold. Some people have asthma flare-ups caused by something in their work environment. Sometimes, asthma attacks occur with no apparent cause.