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Site colors reflect the current ozone Nowcast Air Quality Index
Click a dot to see more information for that location.

National Park Map
Ozone Nowcast Air Quality Index Information
  • Ozone GoodGood
  • Ozone ModerateModerate
  • Ozone Unhealthy for Sensitive GroupsUnhealthy for Sensitive Groups
  • Ozone UnhealthyUnhealthy
  • Ozone Very UnhealthyVery Unhealthy
  • Ozone Data Not AvailableNo Data Available

  • Other (non-ozone) Monitoring SiteOther (non-ozone) Monitoring Site

The NowCast is EPA's method for relating hourly data to the Air Quality Index (AQI). It is designed to be responsive to rapidly changing air quality conditions, such as during a wildfire. The NowCast displays air quality for the current hour by using a calculation that involves multiple hours of past data. The NowCast aligns more closely with what people are experiencing, allowing them to protect their health when air quality is poor and help them get outdoors when air quality is good. For ozone, the NowCast method uses the relationship between 1-hour and 8-hour ozone averages during the prior two weeks to predict an 8-hour ozone average that is centered on the current hour.

Site colors reflect the current Nowcast Particulate Matter (PM2.5) Air Quality Index.
Click a dot to see more information for that location.

Map
Particulate Matter (PM2.5) Nowcast Air Quality Index Information
  • Particulate (PM2.5) matter Nowcast air quality index icon for good condition (green)Good
  • Particulate matter (PM2.5) Nowcast air quality index icon for moderate condition (yellow)Moderate
  • Particulate matter (PM2.5) Nowcast air quality index icon for unhealthy-for-sensitive-groups condition (orange)Unhealthy for Sensitive Groups
  • Particulate matter (PM2.5) Nowcast air quality index icon for unhealthy condition (red)Unhealthy
  • Particulate matter (PM2.5) Nowcast air quality index icon for very-unhealthy condition (purple)Very Unhealthy
  • Particulate matter (PM2.5) Nowcast air quality index icon for hazardous condition (maroon)Hazardous
  • Particulate matter (PM2.5) Nowcast air quality index icon for no data (gray)No Data Available

The NowCast is EPA's method for relating hourly data to the Air Quality Index (AQI). It is designed to be responsive to rapidly changing air quality conditions, such as during a wildfire. The NowCast displays air quality for the current hour by using a calculation that involves multiple hours of past data. The NowCast aligns more closely with what people are experiencing, allowing them to protect their health when air quality is poor and help them get outdoors when air quality is good. For particulate matter, the NowCast is based on the last 12 hours of particulate measurements, with heavier weighting on the most recent hours.

Additional Data