Thaum muas tshuaj pleev thaiv hnub, ua tib zoo saib ob lub ntsiab lus tseem ceeb: SPF (Tsev Tiv Thaiv Factor) thiab dej tsis kam. SPF yog tsim los ntawm cov tshuaj pleev thaiv hnub tiv thaiv UVB. Thaum SPF siab dua txhais tau tias tiv thaiv UVB ntev dua, nws tsis lav zoo ib yam tiv thaiv UVA. Yog tias koj xav tau kev tiv thaiv UVA thiab UVB, xav txog kev yuav tshuaj pleev thaiv hnub "broad-spectrum". Kev tiv thaiv dej yog qhov tseem ceeb zuj zus. Cov hws, dej hiav txwv, thiab dej hauv pas dej ua ke yog txhua qhov muaj peev xwm ntawm kev puas tsuaj, ua rau cov dej tiv thaiv tseem ceeb rau kev ua si sab nraum zoov thiab cov neeg nyiam mus ncig. Raws li American Academy of Dermatology, ib qho SPF tiv thaiv cov tawv nqaij los ntawm lub hnub puas tsuaj rau 10 feeb; Yog li ntawd, ib qho SPF ntawm 15 tshuaj pleev thaiv hnub muab kev tiv thaiv rau 150 feeb. Tsis txhob skimp ntawm tshuaj pleev thaiv hnub zoo li koj xav nrog qhov muag cream; siv ib qho nyiaj pub dawb txhua lub sijhawm. Siv tshuaj pleev thaiv hnub 30 feeb ua ntej mus rau hauv lub hnub (los yog dej) kom cov khoom xyaw nquag nkag mus rau hauv daim tawv nqaij.
