Rénwéi yīnsù shì dǎozhì huánjìng èhuà de zhǔyào yuányīn.
Human factors are the main cause of environmental degradation.
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usage
人为 emphasizes that something is caused by humans (often negatively), while 人造 means 'man-made' as in manufactured/constructed. 人为因素 = human factors; 人造卫星 = man-made satellite.