Table 1.

The classification of the primary and secondary UFUs sampled in Haikou for this study.

Primary UFU	Number	Secondary UFU	Number
Institution business area	44	Hospital	6
		Government organization	8
		Primary and secondary schools	15
		Research institutes	7
		University	8
Industrial and commercial area	19	Industrial area	11
		Commercial area	8
Residential area	31	High-rise residential	26
		Low-rise residential	5
Leisure and entertainment area	7	Parks	6
		Square and sport center	1
Transport area	10	Road	8
		Transportation hub	2
Total	111		111