Disrespect of the Tombs of Ma’sūmīn (a.s.) is Kufr
The respect of the tombs of the Holy Prophet (S) and the Pure Imams (a.s.) is Wajib and a necessity of faith and their disrespect is a greater sin. In fact it is considered the greatest sin to the extent of Kufr and Shirk. If a tomb gets polluted and no disrespect is evident, on the basis of precaution, it is necessary to purify them.
According to jurists as in the case of mosques it is not permitted for Junub person, Haiz and Nifas ladies to stay in the holy Shrines. Some scholars even maintain that even passing through them is not permitted for polluted person, just as it is not allowed for Masjidul Harām.