AQI explained: what the number can—and cannot—tell you

The short answer

A higher Air Quality Index generally means greater potential concern from outdoor air pollution. In the United States, AirNow groups daily AQI values from Good through Hazardous and explains that sensitive people may face concern before the general population.

What is behind the AQI?

The displayed number may be driven by particles such as PM2.5 or by ozone and other regulated pollutants. That matters because the pattern through the day can differ. HiAir therefore keeps the environmental signals explainable instead of treating the headline number as the whole story.

Why a personal view is useful

Two people can make different plans under the same conditions. Intended activity, heat, humidity and personal sensitivity can change whether the practical next step is to shorten a workout, choose a later hour, or follow an official local advisory.

What to do next

• Check the current AQI and the pollutant responsible.
• Look at the hourly trend, not only the daily maximum.
• Consider heat and the intensity of your planned activity.
• Follow local authority guidance during smoke or pollution events.

Primary reference: AirNow — AQI Basics.