Fine particle pollution in the air across southern Minnesota is causing unhealthy breathing conditions for children, the elderly and people with respiratory diseases.
An air pollution health alert is in effect for the Twin Cities metro and Rochester. It expires at 12 a.m. Wednesday.
Cassie McMahon with the Minnesota Pollution Control Agency said a storm system across the Great Plains has trapped stagnant air over Minnesota, allowing pollution levels to rise.
"What happened overnight was those levels continued to build, the wind died down significantly and we also had a bit of a warm up yesterday," McMahaon said. "So overnight when the sun went away the surface was warmer than the air above it which creates an inversion which then traps the pollution near the surface."
Fine particles can make asthma worse and lead to heart attacks, McMahon said. She said sensitive people should reduce their activity level during the pollution alert.
"Having a Hepa filter in your home can help reduce the amount of pollution that you're exposed to, but really the fine particle levels are pretty uniform throughout inside and outside," McMahon said. "The fine particle levels are going to be elevated everywhere."
Fine particles are produced from motor vehicle exhaust, gasoline powered engines and wood burning. Residents are asked to reduce or postpone unnecessary vehicle trips, engine idling and other fine particle-creating activities during the alert.
This is Minnesota's first air pollution health alert this winter. The MPCA expects conditions to improve later this afternoon as wind speeds increase.