I can post a pic if needed, but it's hard to catch the little buggers. Basically, over my entire city, I get a green sparkle effect. it's pretty recent, is it caused by a particular lot or is it a modd issue? I would expect someone else has seen this by now, but I saw nothing in the boards when I looked.
Believe is either radiation effects, from a explosion or an effect from a specially modded lot, buggi created a super park that had this effect to it in which he modded the radiaction to be plus effects not negative. Check for any recently added plopable building or parks as the effect can be added to any lot, think there is also a glow of life easter egg , that may also add this effect to your city.
turns out it was radiation, and not the good kind. I didn't think of it because I plopped no lots with radiation effects that I know of. Swell, IDK which lot even did it now.