These particles being, dust, pollen, and moisture, to name a few. Please note however that regular film cameras can also pick up these artificial orbs, but it is much more rare and they are always fewer in numbers. A general rule is to look for some substance within the orb structure for authenticity. It's best to use them as a team. Ghosts are not just in haunted old buildings.
Ghosts are almost everywhere in one form or another.
So don't be afraid to take photos at the mall or out on a busy intersection at night, or anywhere else for that matter. When you take photos at night, let's say in a cemetery etc. If your camera has this setting, please use it otherwise your photos might come out to dark or fuzzy. Always take photos of something and not just a clearing. Having a background image such as a tombstone, tree, building etc.