Hot Days, Higher AQI: Use CDC’s HeatRisk Tool to Prevent Asthma Flares

Hot days don’t just raise temperatures—they can also worsen asthma through dehydration, heat-related changes in breathing, and air pollution (including ozone and particle pollution). A practical way to prepare is to check CDC’s HeatRisk forecast for heat risk and the Air Quality Index (AQI) for air-pollution risk, then adjust your day before symptoms flare.

Step 1: Check CDC HeatRisk for your area (heat risk)

CDC’s HeatRisk tool is a 7-day health-based heat forecast. It uses a 5-level color scale (green, yellow, orange, red, magenta). Higher levels mean the potential for hot temperatures to cause health harm is greater.

Where to look: Open the CDC HeatRisk dashboard and find your location. If HeatRisk is in a higher color category, plan for more breaks and lower-intensity activity—especially if you have asthma or other health conditions.

Step 2: Add AQI to the picture (air risk)

The AQI helps you understand whether outdoor air quality is healthy. Values from 0–100 are considered “satisfactory air,” and 101–500 are “unhealthy air.” The AQI categories also include guidance for sensitive groups.

Key AQI idea for asthma: For sensitive groups, AQI orange (unhealthy for sensitive groups) is a signal to reduce prolonged or heavy exertion and to follow your asthma action plan while keeping quick-relief medicine handy.

Important limitation: The AQI does not include pollen counts. So on some days, air quality may look “okay” on AQI while pollen-driven triggers still bother some people with asthma and seasonal allergies.

Think “heat + air,” not just temperature

HeatRisk helps you plan for the heat side of the risk; AQI helps you plan for the air-pollution side. On summer days, both can matter at the same time—during outdoor work, sports, smoke events, or humid stretches. A sensible approach: if either tool shows higher risk, scale back outdoor time and intensity and prioritize cleaner indoor air when needed.

Self-care planning before symptoms start

Here are practical steps that fit most people and align with CDC’s HeatRisk/AQI action approach:

Reduce prolonged or heavy exertion when heat risk is higher or when AQI is in ranges that are unhealthy for sensitive groups.
Build in breaks and consider doing demanding activities during cooler parts of the day (or switching to indoor options).
Use cooling basics and rest: hydration, rest breaks, and staying in cooler environments when possible.
Limit exposure to indoor irritants when air quality is poor (for example, avoid activities that add smoke/particles indoors).

Medication planning: follow your asthma action plan

High-risk heat/air days are a good time to confirm you’re prepared—but use your clinician-approved asthma action plan, not improvising.

Follow your action plan if symptoms start, including the steps you’ve been told to take during higher-risk conditions.
Keep quick-relief medicine accessible and don’t forget it when you go out.
Don’t abruptly stop asthma medications unless your clinician tells you to.
Store inhalers safely: CDC notes that high heat can affect medications and that inhalers should not be left in hot cars or other very hot places.

Who may be more likely to worsen?

CDC describes sensitive groups broadly to include people with certain health conditions and specific age groups. For asthma planning, this often includes:

Children and teenagers with asthma
Older adults
People with asthma or other lung disease

Caregivers, schools, and workplaces can reduce risk by matching outdoor time and activity intensity to HeatRisk/AQI and having a clear plan for symptoms and quick-relief access.

When to get urgent help (call 911)

If you or your child with asthma has danger signs, get emergency help right away. Call 911 (or your local emergency number) immediately if any of the following are happening:

Trouble walking or talking because it’s so hard to breathe
Hunching over
Lips or fingernails turning blue or gray
Confusion or less responsiveness than usual

MedlinePlus also lists common warning signs such as coughing (day or night), wheezing, breathing problems (shortness of breath, gasping, fast breathing), and chest tightness. If symptoms are getting worse or not improving as expected based on your action plan, seek urgent medical care.

Bottom line

For asthma, the “next step” is straightforward: check HeatRisk and AQI, plan ahead for higher-risk colors, and follow your asthma action plan. If you repeatedly flare on similar hot, high-AQI days, bring that pattern to your healthcare team to update your plan.

Key sources

Editorial note: Weence articles are researched from cited public-health, medical, regulatory, journal, and reputable news sources and may be drafted with AI assistance. They are checked for source support, clarity, and safety guardrails before publication.

This article is for general informational purposes only and is not medical advice. Research findings can be early or incomplete, and health guidance can change. Always talk with a qualified healthcare professional about personal symptoms, diagnosis, medications, vaccines, screenings, or treatment decisions. If you think you may have a medical emergency, call emergency services right away.