וְכִפֶּר עַל הַקּדֶשׁ מִטֻּמְאֹת בְּנֵי יִשְׂרָאֵל
וְטִהֲרוֹ וְקִדְּשׁוֹ, מִטֻּמְאֹת בְּנֵי יִשְׂרָאֵל
With these and any other instances, it is of utmost importance that it is not pronounced מִטֻּמְאַת, which would change it from plural to singular.
(It should also be noted that while the שוא under the מ is a שוא נח, it is important to create a separation between the מ and א so that the א doesn't disappear and it is pronounced as if it is מטמות, i.e. it should be mitum-os, not mitu-mos.)