Apples to apples, for instance Soviet Union compared to Europe, there is no doubt Soviet union was decades behind the west regarding regulating on toxic compounds and pollution and cleaning up.
Same with China, they build their industrial capacity on polluting without limits, compare that to Japan or South Korea. China even had the advantage pollution wise that they started later, so a lot of know how was available on how to pollute less for comparable industrial output.
At least China has improved, but Soviet union never did.