Microwave ovens have limited power, and unless you are standing right in front of one which is on, you have little to fear. Even backing away a few inches or feet subjects the microwaves to the inverse square law of diminishment. The danger to you is 'heat' that it will cook you. I do not think microwaves constitute ionizing radiation (like in nuclear reactors and nuclear medicine). Also, the waves tend to concentrate in the outside surfaces of things. So you would feel them and instinctively move away.
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