Chinese cooking can be especially greasy. Kitchens in older-style apartment are often very small, enclosed spaces to keep the grease from traveling throughout the house. They are often so small that refrigerators (even though the ones here are roughly half the size of the American standard) are located in the dining room or elsewhere in the house.
Most of these range hoods have built-in containers to catch the grease.
However, there are times where it will still need a good clean. And, for such times, there are door-to-door cleaners.