Because I work the night shift and get off work at 3-4 in the morning, can I run in the early morning if I want to exercise?

Try not to. The air in the morning is very dirty. At that time, there were few vehicles and people, and more dust would fall to the ground. There is also a security issue. If you work at night, you'd better go home to sleep after work and exercise before going to work in the afternoon (it's hot outside, you can go to the gym treadmill)