防晒霜包装上一般都标有SPF和PA，SPF是指防晒指数，是针对UVB紫外线的，我们常见的SPF指数有15、30、50等。
Sunblock is generally marked with SPF and PA on the package. SPF refers to Sun Protection Function and is targeted at UVB. The common SPF index includes 15, 30, 50, etc.