Well, most likely particles in the smoke. Also notice some of the orbs are the same color as the light on the porch.  

when I was trained with my former paranormal group I was told that when you see orbs in photos one of the first things you have to check is to see weither they're transparent or not. of they aren't you need to look around the photo and see where they were taken. for example your phOtis were taken outside and I see there's a fire you could have captured ambers from the fire or bugs. I hope that my input was helpful !