You don't need UWB for safety alerts. Simply bluetooth is enough. These tags send out a message every 2 seconds and have a predictable part of the rotating key so if you see the same fixed portion multiple times in a row, its very likely to be the same tag (unlikely that multiple different tags were near you one at a time with exactly the same fixed part) but if you do something like set up tracking stations at malls, there will be too many duplicates.