Understanding the Air Quality Index

The Air Quality Index (AQI) is a simple way to turn complex pollution measurements into a single number you can act on. Instead of interpreting separate readings for ozone, fine particles, and other pollutants, the index rolls them into one scale.

How to read the scale

On most dashboards, including Aether, lower numbers mean cleaner air:

• 0–50 (Good): Air quality is satisfactory for most people.
• 51–100 (Moderate): Acceptable for the general public; unusually sensitive people may notice effects.
• 101–150 (Unhealthy for sensitive groups): Children, older adults, and people with asthma or heart disease should limit prolonged outdoor exertion.
• 151–200 (Unhealthy): Everyone may begin to experience effects; sensitive groups should avoid prolonged outdoor activity.
• 201+ (Very unhealthy / Hazardous): Reduce outdoor activity and follow local health advisories.

Which pollutant drives the number?

AQI is based on the worst pollutant at a given time. If PM2.5 is elevated but ozone is low, the index reflects whichever poses the greater risk right now. That is why the dominant pollutant can change through the day.

Practical tips

Use AQI as a daily planning tool: check before exercise, school sports, or opening windows. Pair the index with the hourly forecast on Aether to see whether conditions are improving or deteriorating.

Aether combines model estimates and ground stations where available. For medical decisions or official alerts, always follow guidance from your local environmental health authority.