What is AQI (Air Quality Index)?
Read how AQI categories, pollutant breakpoints, and one familiar number can make outdoor air easier to interpret.
Learn
Learn about air quality
Air quality can feel invisible until a hazy morning, a smoky afternoon, or a run that feels heavier than expected. These short guides explain AQI, outdoor pollution, annual PM2.5 city rankings, and air-quality measurement in the same practical language used across Air Quality Router.
The app's Activity & Air notes use the same evidence-aware approach to connect air-quality context with common outdoor routines. They support planning and awareness rather than medical guidance or personal exposure measurement.
The measurement guide also covers how public air-quality data can grow through community outdoor monitors, including the AirGradient OpenAQ sharing path as one available example. AirGradient, OpenAQ, and Air Quality Router remain separate organizations and services; no endorsement is implied.
Outdoor pollution and why AQI matters during walking or jogging
See why breathing rate, route timing, traffic, and changing AQI can make the same outdoor routine feel different from one hour to the next.
How air quality is measured and assessed
Follow the path from station readings and community sensor metadata to forecast fallback and concentration-to-index assessment.
Best and worst air quality cities in 2025
Compare source-backed annual PM2.5 rankings for the cleanest and most polluted cities, then bring the lesson back to local AQI planning.
Put air-quality context into the next route decision
Air Quality Router compares practical walking and jogging routes with estimated AQI, source freshness, and cleaner-hour timing.
