1 ppm = 1,000 ppb = 1,000,000 ppt

parts per million 百万 - ppm

1 ppm = 1 milligram/kilogram (mg/kg)
1 ppm = 1 milligram/liter (mg/l)
1 ppm = 1 microgram/gram(μg/g)
1 ppm = 0.0001 % = $10^{-6}$

parts per billion 十亿 - ppb

1 ppb = 1 microgram/kilogram (μg/kg)
1 ppb = 1 microgram/liter (μg/l)
1 ppb = 1 nanogram/gram(ng/g)

1 ppb = $10^{-9}$

parts per trillion 万亿 - ppt

1 ppt = 1 nanogram/kilogram (ng/kg)
1 ppt = 1 nanogram/liter (ng/l)
1 ppt = 1 picogram/gram (pg/g)

1 ppt = $10^{-12}$

milligram - 毫克 - $10^{-3}$克

microgram - 微克 -$10^{-6}$克

nanogram - 纳克 - $10^{-9}$ 克