Usage patterns
劣悪な環境a poor/substandard environment
The factory made its employees work in poor conditions.
劣悪な待遇poor treatment (of workers, etc.)
Migrant workers are often subjected to poor treatment.
劣悪な条件poor/harsh conditions
They kept working under harsh conditions.
劣悪化するto worsen; to deteriorate (in quality)
Public safety deteriorated due to the worsening economy.