Rock Products - The Leading Voice of the Aggregate Industries.

Minnesota City Monitors Silica Levels


In January 2014, the Minnesota Pollution Control Agency (MPCA) placed air-quality monitors in the city of Winona, Minn. The monitors were placed primarily to measure general particulates and crystalline silica adjacent to a silica sand transportation route.

The real-time information gathered is given a PM2.5 Air Quality Index (AQI) number. The index numbers correspond to the following categories:

  • (0-50) Good: No potential issues.
  • (51-100) Moderate: Unusually sensitive people should consider limiting prolonged outdoor exposure.
  • (101-150) Unhealthy for sensitive groups: Active children and adults, and people with respiratory disease, such as asthma, should limit prolonged outdoor exertion.
  • (151-200) Unhealthy: Active children and adults, and people with respiratory disease, such as asthma, should avoid prolonged outdoor exertion; everyone else, especially children, should limit prolonged outdoor exertion.
  • (201-300) Very Unhealthy: Active children and adults, and people with respiratory disease, such as asthma, should avoid all outdoor exertion; everyone else, especially children, should limit outdoor exertion.
  • (301-500) Hazardous: Everyone should avoid all outdoor exertion. 

 

Data collected from January through March from one of Winona’s air monitors on top of the Winona YMCA was recently published by MPCA. With the exception of a single day, results from the combustion emission fine-particles monitor – which measures anything that burns fuel and gives off emissions 2.5 microns or less –show levels were well below the health standard set by the Environmental Protection Agency, according to the Winona Daily News.

One day exceeded the EPA standard for combustion emissions, and the reading was seen around much of the region that day. “(It) was the result of a regional weather pattern that included a strong temperature inversion, light winds, and heavy fog,” a MPCA report said.

Additional data will be forthcoming as the project proceeds.