St. Paul– The Minnesota Pollution Control Agency (MPCA) has found that air quality in an industrial part of North Minneapolis recently violated a state standard for large airborne particles.

“Although it isn’t an immediate health threat, this is a situation that concerns us,” said MPCA Industrial Division Manager Jeff Smith. “These larger particles are less of a health risk because they can’t be inhaled deeply into the lungs like small particles. However, any violation of this nature is a serious matter.”

The violation was detected by an air monitoring station near the Lowry Avenue bridge on the west bank of the Mississippi River. Levels of large particles, also known as Total Suspended Particulates (TSP), exceeded the state standard on October 26 and November 1, 2014. This triggered an MPCA investigation into possible sources and corrective actions. That investigation is ongoing.

Smith said, “We know these larger particles tend to be heavier and do not travel far. Therefore the cause of the violation, and any effects, are likely to be within about a quarter-mile of the monitor.”

The station that detected the violation monitors the overall quality of the ambient, or background, air in that area. It does not measure the emissions from specific nearby sources such as regulated industries – which are monitored separately. There may be multiple nearby sources that contributed to the problem.

Monitoring has continued since the violation was identified. Although additional violations have not been detected, the MPCA is looking into all of the potential sources that may have caused or contributed to the violation, and is moving quickly to identify specific actions to prevent future violations.

The MPCA began operating a fine-particle monitor at the site in January 2013, which measures particles of 2.5 microns or less (a human hair is about 70 microns in diameter). Fine particles are of a greater concern to human health because they can be inhaled more deeply into the lungs. The fine-particle monitor was installed partly in response to community concerns about air quality, and has not shown any problems since start-up. MPCA discovered the large-particle violation after it expanded the types of particles monitored at the station in October 2014 to compare with other monitors in the Twin Cities.

“We will continue to follow up to see if the high levels of large particles were isolated to just those two days, or whether they’re part of a larger pattern,” Smith said.  “Despite the fact our investigation is not complete, we’re already taking steps to identify potential contributors and work with them to reduce their emissions.”

The mission of the MPCA is to protect and improve the environment and enhance human health.
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