Millions of tonnes of nanoplastics are polluting the ocean

> The tiniest of pieces of plastic, nanoplastics are defined by the researchers as having a diameter of less than one micrometre (one one-thousandth of a metre). Microplastics are between one micrometre and 5 millimetres across.

Isn’t a millimeter one one-thousandth of a meter and a micrometer one one-thousandth of that (or one-millionth of a meter)? I don’t have to reason about objects this small very often so I was trying to make sense of the relative sizes and this threw me off.

Of course mistakes happen, so whatever, hopefully it’s corrected shortly; I’m just surprised to see something so easily check-able as a unit definition get missed in a publication like Nature.