Question: how many ppb to ug/kg?
Answer: ppb↔ug/kg 1 ppb = 1 ug/kg. ppb↔ul/l 1 ul/l = 1000 ppb. ppb↔nl/ml 1 nl/ml = 1000000 ppb. ppb↔ml/m3 1 ml/m3 = 1000 ppb.