The test and assessment for the homogeneity of a certified reference material are introduced. 介绍标准物质的均匀性检验及其评价方法。
In the U.S., health care workers, and other employees that are required to wear respirators must do a fit test before wearing the respirator for the first time. 在美国，医疗机构内的医护人员及在工作场所中使用呼吸器的其他雇员，在第一次佩戴呼吸器时，都必须进行适合性检验。
