I can't see your photos Henri. But Peg's is a good one.
We went to Phuket before and after the tsunami which swept away so many people to their deaths. We befriended the owner of a beach cafe/restaurant.
DH's parents took photos of her with them on the visit before the tragedy and after, and the photos taken after were absolutely teeming with orbs - maybe 25 in one shot, some overlapping. None in the first visit. Same place, same camera, same people, 2 years apart. Yes it could have been dust, or bugs. At a stretch.