A formal or technical term for an unpleasant smell, often used in legal, environmental, or scientific contexts. In everyday speech, 悪臭 or 臭い are more common.
A foul odor drifted over from the factory.
Measures to prevent bad smells are being called for.
The odor near the factory is strong, and residents have been filing complaints.
The waste treatment facility constantly emits a foul odor.
臭い is the plain, everyday word for a smell (good or bad depending on context), while 臭気 is a stiffer term specifically for a bad odor.
芳香 means a pleasant fragrance, the direct opposite of 臭気, which refers to an unpleasant odor.
臭い (くさい) is the adjective 'smelly' describing something directly, while 臭気 (しゅうき) is a noun referring to the odor itself as a substance or phenomenon.
Compound of 臭 (bad smell) and 気 (air, atmosphere). The combination conveys the idea of a foul odor in the air.
This device was installed to remove the foul odor indoors.
The investigation found that the drainage system was the source of the odor.