You can test for mold using an air quality monitor that has a PM1.0. That means it detects particles <1 μm in size which is good for bacteria. Combine that with an air purifier suitable for the size of the cellar.
Windows to cellars should already have trickle vents otherwise it could get damp pretty quickly. Look carefully at the frame of the small window. If no trickle vent, look to install one.
You can test for mold using an air quality monitor that has a PM1.0. That means it detects particles <1 μm in size which is good for bacteria. Combine that with an air purifier suitable for the size of the cellar.
Windows to cellars should already have trickle vents otherwise it could get damp pretty quickly. Look carefully at the frame of the small window. If no trickle vent, look to install one.