Air Quality
Air Quality Index Explained: AQI Colors, PM2.5, Ozone, and Sensitive Groups
A guide to AQI colors, fine particles, ozone, sensitive groups, and how to use air quality forecasts for outdoor plans.
Quick answer: The Air Quality Index is a color-coded scale that translates pollution levels into practical health guidance.
AQI colors
Green and yellow usually mean lower concern for most people, while orange and worse can affect sensitive groups or the broader public.
The pollutant driving the number matters.
PM2.5 and ozone
PM2.5 is fine particle pollution from smoke, combustion, and other sources.
Ozone often builds on hot sunny days with certain emissions and stagnant air.
Planning use
Use AQI forecasts to adjust exercise, school activities, outdoor work, and ventilation choices.
People with asthma, heart disease, lung disease, children, and older adults may need extra caution.