Current Air Quality
Monitoring Air Quality
The map below provides data for pollutants measured at specific locations in Benton County’s monitoring network. Select a site to access types of monitors and additional data, including current and five-day trends. To see current air quality outside of Benton County, visit AirNow or the Department of Ecology’s monitoring network for more information.
EPA’s Air Quality Index (AQI)
The AQI is a national uniform system, defined and used by the EPA, to report pollution levels for the criteria air pollutants regulated under the Clean Air Act. The AQI provides citizens with information about the general health effects associated with different pollution levels.
Monitoring and Forecasting FAQ’s
The AQI is divided into these six categories:
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Good – Air quality is considered satisfactory, and air pollution poses little or no risk. Numeric Value: 0-50
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Moderate – Air quality is acceptable; however, for some pollutants there may be a moderate health concern for a very small number of people who are unusually sensitive to air pollution. Numeric Value: 51-100
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Unhealthy for Sensitive Groups – Members of sensitive groups may experience health effects. The general public is not likely to be affected. Numeric Value: 101-150
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Unhealthy – Everyone may begin to experience health effects; members of sensitive groups may experience more serious health effects. Numeric Value: 151-200
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Very Unhealthy – Health alert: everyone may experience more serious health effects. Numeric Value: 201-300
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Hazardous – Health warnings of emergency conditions. The entire population is more likely to be affected. Numeric Value: 301-500
What does Current Air Quality represent?
Pollutant concentrations are converted to the Air Quality Index (AQI). The pollutant with the highest value (the predominant pollutant) is reported for the “Current Air Quality.” The AQI is updated each hour.
The air quality monitoring network measures concentrations of three air pollutants: PM10 (coarse + fine particles), PM2.5 (fine particles) and Ozone (measured May-Oct during ozone season.) The monitoring map (above) provides data for each monitoring site in Benton County. You can view the current day trend, or you can view a 5-day trend for each site. Some sites measure multiple pollutants.
How is the AQI calculated for the Current Air Quality?
Each pollutant has its own health-based standard. For particulate matter, it is a 24-hour average, midnight-to-midnight. This means the official daily AQI is not known until the following day. A rolling 24-hour average report also isn’t very useful when conditions rapidly change, such as during a dust storm or wildfire. To address this, EPA developed the NowCast to report air quality that is near real-time (referred to as “Current Air Quality” reported at the top of this webpage.)
The NowCast calculation is designed to be responsive to rapidly changing air quality conditions. More recent hourly air pollution readings (e.g., last three hours) are given greater weight in determining the NowCast index value when air quality is changing more rapidly, as may be the case when wildfire smoke affects air quality.
Why don’t we provide a one-hour, stand-alone value? Because there is not a one hour health-based standard. For ozone, the standard is an eight-hour average, and for particle pollution it is a 24-hour standard. The NowCast is a very effective tool to report near real-time air quality that correlates to the health-based standards. Learn more about the AQI and NowCast calculations.
Why is the AQI updated only once an hour?
Each hour, readings from our air quality monitors are automatically uploaded to the statewide air quality monitoring telemetry system and then to EPA’s AirNow.gov. Data goes through a quality check, and then at :35 past each hour, our website is updated with the most recent hour of data. So, the Current AQI updated at 1:35 pm is monitored data from Noon-1pm. At 2:35 pm, the 1-2 pm data is reported. The delay enables our system to ensure we are providing the best quality data. If a monitoring site has a malfunction, this potentially “bad data” can be removed from the reporting so that the AQI isn’t erroneously reported.