One way scientists compare ionizing radiation exposure is a unit called the sievert.

科学家们区别电离辐射暴露的一个方法是一种叫西韦特的单位。

An acute exposure to one sievert will probably cause nausea within hours, and four sieverts could be fatal.

一西韦特的急性暴露下可能会造成几个小时的恶心，四西韦特可以致命。