Breakdown of kono uirusu wa kuukichuu de hirogarimasu.
はwa
topic particle
このkono
this ... adnominal
空気kuuki
air
〜中〜chuu
throughout, during
Sometimes the initial t-sound changes into a d-sound due to rendaku, a phenomenon where the initial consonant of the second part of a compound word becomes voiced.
Unfortunately, there are no clear rules for when rendaku applies.
