>> Questions or Comments: monops@tceq.texas.gov
You are here:

Interpret the AQI Rating

Information about interpreting the EPA's Air Quality Index rating and scale.

Each National Ambient Air Quality Standards (NAAQS) pollutant has a separate AQI scale, with an AQI rating of 100 corresponding to the concentration where health effects for each pollutant begin to affect the general public. AQI ratings below 100 indicate no appreciable health risk.

Additional information about the AQI and how it can be used is available from the EPA.Exit to EPA

The AQI scale is divided into the following categories:

AQI Air Quality Scale

The AQI for ozone is based on the either the peak eight-hour running average since midnight OR the peak one-hour measurement since midnight. The AQIs for PM-10 and PM-2.5 are based on a 24-hour average sampled from midnight to midnight. The AQI for carbon monoxide is based on the peak eight-hour running average since midnight. The AQI for sulfur dioxide is based on the either the peak one-hour measurement since midnight OR the peak 24-hour average sampled since midnight. On most days the critical pollutant is ozone. Ozone one-hour average concentrations of 125 ppb or higher exceed the old NAAQS. The new NAAQS for ozone is based on eight-hour averages; an eight-hour average of 71 ppb exceeds the new NAAQS for ozone.