What is the definition of a healthy city?

A healthy city is a city that can provide people with good living environment, good health and low crime rate.

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healthy city應擁有甚麼呢?
(1) 好的居住環境，少污染。
(2) 人民的健康良好，少疾病傳染。
(3) 安全，犯罪率低。