SOUTH DAKOTA Department of
Environment & Natural Resources

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Air Quality

Natural Events Action Plan
High Wind Dust Alerts


Air Quality Status:  "No high wind dust alert issued for today."  Click here for data

 

Past High Wind Dust AlertsNatural Events Action Plan Logo

Area of impact

Meteorological Criteria

High Wind Dust Alert Issuance

Health Precautions During an Alert

Voluntary Actions to Reduce Air Pollution Levels

Basis for Criteria Selection


Area of Impact: Applies only in West Rapid City beginning at the "Gap".

Meteorological Criteria:

If the following weather conditions exist, a high wind dust alert  will be called:

1. Five consecutive days of 0.02 inches or less of precipitation each day, excluding dry snow;
2. The forecasted peak wind gust greater than 40 mph; and
3. The forecasted average hourly wind speed greater than 20 mph.

The high wind dust alert will be discontinued when the following weather conditions exist:

1. Wind speeds decrease below 12 mph on an hourly average and peak wind gusts are below 30 mph; or
2. There is greater than 0.02 inches of precipitation in a 24 hour period excluding dry snow.

High Wind Dust Alert issuance: An alert will be issued and subsequently cancelled by the National Weather Service.   The National Weather Service will notify the media as well as the Rapid City Air Quality Program or the department in the following sequence:  Jon Epp, SD DENR - Rapid City (work 394-5200), Air Quality Coordinator, Rapid City Air Quality Program (work 394-4120),or Brad Schultz, SD DENR - Pierre (work 605-773-3151).

Health Precautions: During an alert, elderly citizens, young children and individuals with respiratory problems should avoid excessive physical exertion and minimize outdoor activities. Although these people are the most susceptible to health impacts, it is recommended that everyone take precautions to avoid being exposed to these poor air quality conditions.

Voluntary actions to reduce air pollution levels: To minimize pollution levels, it is recommended that any manipulation of soils (i.e. construction, or industrial or agricultural activity) cease or be minimized during these events. It is also recommended that pollution controls for soil stabilization, process equipment, waste pits, stock piles and construction sites (i.e. watering or chemical treatment) be increased.

Basis for criteria selection: High wind/dust conditions typically occur after extended dry periods during the colder months of the year and have, on occasion, caused air pollution problems during warmer months. Therefore, high wind dust alerts will be called year-round. High air pollution levels occur when peak wind gusts reach 40 to 70 miles per hour and average hourly wind speeds are greater than 20 miles per hour for an extended period of time. The high winds strip away the top crusted layer of the soil and suspend the finer dust particles in the air. The high wind events can last from one to eight hours depending on the strength of the storm system.

During these events, the hourly dust concentrations have ranged from 100 ug/m3 to 900 ug/m3 per hour. A violation of the dust health standard is a reading over 150 ug/m3 averaged over a 24-hour period. This standard has been violated during these conditions in West Rapid City. Therefore, air pollution alert for dust will only be called for the West Rapid City area. A review of monitoring data indicates that high concentrations only occur in this area of town during these high wind events.

Past High Wind Dust Alerts:  The following is a list of high wind dust alerts that have been called in Rapid City during the past year.  By clicking on the date, you can view the weather conditions and PM10 concentrations.

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