Respiratory Diseases
Asthma
What asthma is, common triggers studied in public health, and what adult asthma estimates represent.
Beginner explanation
Asthma is a chronic (long-term) condition that affects the airways — the tubes that carry air in and out of the lungs. In people with asthma, the airways can become inflamed and narrowed at times, which makes it harder for air to flow out when breathing out.[2]
A person with asthma has it all the time, but has asthma attacks only when something bothers the lungs. It is one of the most common long-term diseases of children, but adults have asthma too. About 1 in 13 people in the United States have asthma.[1, 2]
Key definitions
- Airways
- The branching tubes that carry air to and from the lungs.
- Asthma attack
- A worsening of symptoms in which airway walls swell, airways shrink and mucus clogs them, so less air moves in and out.
- Trigger
- Something that sets off or worsens asthma symptoms, such as pollen, exercise, viral infections or cold air.
- Spirometry
- A breathing test that measures how much air a person can breathe out after a deep breath, often before and after asthma medicine.
- Controller and reliever medicines
- Controller medicines help people have fewer and milder attacks; reliever medicines treat symptoms when they happen.
Condition characteristics
Asthma causes wheezing, breathlessness, chest tightness and coughing, often at night or early in the morning. An attack may include coughing, chest tightness, wheezing and trouble breathing.[1]
Diagnosis can be hard, especially in children under 5. A doctor may ask about coughing (especially at night), whether breathing problems worsen with activity or at certain times of year, colds lasting more than 10 days and family history of asthma or allergies, and may use spirometry.[1]
There is no cure, but treatment and an asthma action plan — monitoring, avoiding triggers and using medicines — help people manage the condition.[2]
Risk factors
Asthma affects people of all ages and often starts in childhood. Things that can set off or worsen symptoms include pollen, exercise, viral infections and cold air.[2]
Homes can contain triggers too. CDC supports trained home visitors who look for common triggers such as dust mites and mold or moisture, and help families reduce them; removing triggers in the home, along with proper medical care, can improve health.[1]
Prevention and public health context
People can control asthma by knowing the warning signs of an attack, staying away from their triggers and taking medicine exactly as prescribed. Not everyone with asthma takes the same medicine; anyone needing their reliever medicine more and more often should see their doctor.[1]
CDC’s home-visit checklist reflects a public health approach that pairs medical care with simple, low-cost steps to find and remove triggers in the home.[1]
Texas data context
The PLACES current asthma measure on MedEquity estimates the share of adults who answer yes both to having ever been told by a doctor, nurse or other health professional that they have asthma and to still having asthma. It is a modeled estimate for adults only — childhood asthma is not represented.[3]
CDC advises considering confidence intervals and population differences when comparing counties, and not using PLACES to track change over time.[4]
Related measures on the Explore map
- Current asthma among adults (modeled estimate)
Advanced material (optional)
References
- About Asthma. Centers for Disease Control and Prevention. https://www.cdc.gov/asthma/about/index.html (accessed 2026-10-18).
- Asthma — What Is Asthma?. National Heart, Lung, and Blood Institute (NIH). https://www.nhlbi.nih.gov/health/asthma (accessed 2026-10-18).
- PLACES Measure Definitions: Health Outcomes. Centers for Disease Control and Prevention. https://www.cdc.gov/places/measure-definitions/health-outcomes.html (accessed 2026-10-18).
- PLACES: Frequently Asked Questions. Centers for Disease Control and Prevention. https://www.cdc.gov/places/faqs/index.html (accessed 2026-10-18).