The AirNow Map image above shows that there is a moderate level of ozone (AQI between 51-100, in yellow) over Lake Michigan and Lake Huron.
NOAA Aerosol Watch image above that shows a greenish to a yellow hue of AOD over Lake Huron and Lake Michigan. The high AOD in this region is associated to smoke from seasonal fire activity was scattered across Minnesota, eastern and northern North Dakota, and the southern portions of Saskatchewan and Manitoba, with a number of the plumes merging to form a larger patch
The NASA Worldview image above shows a growing mass of dust over the Sahara Desert. The dark red and green mass is mostly concentrated over Algeria.
The NRL/Monterey Aerosol image above supports this claim as there is an increased concentration of dust over Algeria. The center of the concentration reaches levels greater than 10240 ug/m**3 (in pink).