Orb Swarm in Very Clean Air

Photo date: November 17, 2014. Photographer: Mark Mahin.

At the time this indoor picture was taken of a featureless wall, an air quality monitor showed the air quality was very good, with a reading of  45/2 (anything below 50 is "very good" air according to the monitor's back plate). Dust cannot account for the image, because the air was too clean for dust to be a plausible explanation.   The image below was color-adjusted using the "Auto-adjust colors" menu option in the IrfanView program.

Reflective surfaces nearby: none. No orbs were seen in photos shortly before and shortly after this picture was taken, which argues against any dust explanation. No artificial light was involved in the photo area except the camera flash. No insects were observed at the photo site.