torsdag 18. mars 2021

Beijing’s ‘sandstorm’ was actually a dust storm – and that’s much worse

The problem, at least in terms of public health, is that it was not actually a sandstorm. It was a dust storm. This might sound like an act of geological pedantry, but it represents a crucial difference, and it comes down to a question of size. Sand grains are mineral particles greater than 0.06mm in diameter – the sort that scratches your ankles on a windy day at the beach and ends up spoiling the picnic by feeling crunchy in your sandwiches. Dust is potentially a far more serious issue than blowing sand.

Dust particles (or silt and clay as many geologists would term them) are those smaller grains, which would feel silky to the touch, and don’t scratch the skin. Crucially, these smaller, lighter grains may travel much, much further.