By Erik Runkle and Heidi Lindberg
Smoke from the wildfires in the boreal forests of northern Minnesota and Ontario, Canada has been in the news almost every day for the last week. Michigan has been one of the most affected states, with thick smoke that has decreased visibility to a mile or less. Pollution from wildfire smoke also made the news in Michigan in 2023 and 2025, but the fires were farther away in British Columbia and Alberta. As a result of the smoke, the particulate matter (PM2.5) significantly reduced air quality in Michigan when the wind came from the northwest. Table 1 shows examples of the air quality index (AQI) at select Michigan locations from July 15 to July 17, 2026.
Table 1. Air Quality Index (AQI) values for July 15 to July 17 at various locations throughout Michigan.
**(0-50: Good, 51-100 Moderate, 101-150 Unhealthy for Sensitive Groups, 151-200 Unhealthy, 201-300 Very Unhealthy, 301+ Hazardous)
Not surprisingly, some of the greatest AQI values were at downwind locations of the fires in the western Upper Peninsula of Michigan, which were 532 on July 15 and 619 on July 16. While the air quality has clearly been dangerous at times for people and their pets, the potential impacts on plants in general, and floriculture crops specifically, are unclear.
At its worst, the smoke decreased sunlight by 20 to 80%, according to MSU Enviroweather stations across the state. A reduction of 20% is not cause for concern since it is comparable to a partly cloudy day. However, heavily affected regions, such as McMillian in the Upper Peninsula of Michigan, reported one of the lowest solar radiation values reaching the ground on 7/15 according to the MSU Enviroweather system (Figure 1). The only other weather event that could cause such an extreme reduction in solar radiation would be dense fog the entire day.
Source : msu.edu