Air Quality Forecasts

Like the weather, air quality conditions can be forecast. APCD works with the Indiana Department of Environmental Management (IDEM) to forecast ozone and fine particle (PM2.5) pollution levels using meteorological expertise and computer models. Monitoring data, collected locally, and meteorological data are used to generate the forecast.

For Ozone

  • Forecast peak 8-hour average concentrations for one to three days ahead
  • Concentrations are forecast from April to October, the months when high ozone is likely in the Louisville area

For PM2.5

  • Forecast peak 24-hour average concentrations for a three- or four-day period
  • Concentrations are forecast year round

Forecasts are reported in Air Quality Index (AQI) values. APCD issues an Air Quality Alert when air pollution is forecast to reach unhealthy levels (AQI value > 101). Alerts may be used to:

  • Help citizens avoid air pollution related health impacts; and
  • Encourage businesses and individuals to take action to reduce polluting activities.

You can learn more about the health impacts of air pollution and actions you can take to reduce air pollution at KAIRE’s website


APCD also participates in EPA's AIRNow website to provide the public with easy access to national air quality information. AIRNow offers daily AQI forecasts as well as real-time AQI conditions for over 300 cities across the US. To provide “real-time” AQI conditions, AIRNow displays data as soon as practical after the end of each hour. Although some preliminary quality assessments are performed, the data are not fully verified or quality assured and are intended to be used in reporting and forecasting the AQI only.


EnviroFlash is a system that sends e-mails about your daily air quality forecast. The message is the same air quality information that the local media provide, along with suggested safety measures when levels are unhealthy. This service is provided by APCD and the EPA.

With EnviroFlash you can:

  • Receive Air Quality Alerts wherever you are, at home, at work, or on the go; and
  • Choose to receive air quality forecasts and at what level to be notified.

EnviroFlash is especially helpful for people who are more sensitive to the effects of air pollution, such as the young, people with asthma, and the elderly. Sign up for EnviroFlash Today!