According to § 5 paragraph 3 of the Special Containment Measures Ordinance, qualified masks are OP masks of type II or II R with CE marking, FFP2 mask without exhalation valve, FFP3 mask without exhalation valve or mouth-nose covering according to the standards KN95 and N95, each without exhalation valve.
Entry to and stay in the University Library therefore is only permitted with a qualified (medical) mask.