Production will always have some waste and pollution. China has high pollution because we do a lot of production there. As I pointed out above, on both a per-capita and a per-production basis China pollutes less than many industrialized nations (US. Germany, Japan, South Korea, Canada, Taiwan) and many developing nations (Singapore, Malaysia).
Given current manufacturing data, moving production out of China to other countries would likely increase pollution.
Do you have a better metric?