Image credit: Minnesota Pollution Control Agency.
On June 14, Minnesota had the worst air quality in the country, with the Air Quality Index reaching the “Very Unhealthy” category.
Minnesota has been plagued by smoke from wildfires from Canada in May and June. The latest event had some of the densest smoke move right over the Twin Cities. The Twin Cities International Airport began reporting smoke at Noon on June 14 and reported smoke for 19 hours straight ending at 6am June 15. The sun was reduced to a pale disk in the sky. It even appeared hot pink at 7:30pm June 14 in St. Paul The thickest smoke in the Twin Cities was from 7-9pm on June 14, with visibilities down to one mile and a quarter, giving the evening a gloomy, foggy feel to it. The average Air Quality Index (AQI) for June 14 for the Twin Cities was 175, which is the highest daily average measure recorded in the Twin Cities since Air Quality Index records began in 1980.
The wildfire smoke contained fine particulates that drifted south and large areas of northern, central and southern Minnesota at times were in the Red (“Unhealthy”) category in the Air Quality Index. Some of the Pollution Control Agency’s sensors in central Minnesota, including parts of the Twin Cites, indicated air quality had degraded into the Purple (“Very Unhealthy”) category in the late afternoon and evening. Reduced visibilities in smoke down to two miles were seen at Duluth and International Falls. St. Cloud had visibilities down to a mile and a half, Rochester down to two-and-a-half miles. These visibilities are more common with fog and falling snow.
Air Quality Advisories begin at when the Air Quality Index (AQI) reaches a value of at least 101, which is the baseline for the Orange or "Unhealthy for Sensitive Groups" category. The Red/Unhealthy category presents risks to the general public and may cause more serious health risks for sensitive groups, and the Purple/Very Unhealthy category increases health risks for everyone.
In recent years, reports of smoke have become more common. There was a quick smoke front on July 6, 2015. In August 2018 there were smoky skies off and on. There was another smoke episode on September 13-15 2020, and a summer of smoke in 2021.