Is that a fact though? If that were the case, Mexico, the US's third-largest trading partner and by most measures, a "developing" county, should be vastly more polluted than India, which is the US's 9th-largest trading partner.
The top-ten polluted cities are in India and Pakistan. China doesn't even make the top 20.[1]
Is Pakistan materially contributing to the high living standards of developed countries? It would be a stretch to suggest that.
However, the high standards of living the developed world are absolutely contributing to rising standards of living in the developing world. If it weren't for trade, South Koreans, for example would still be living in mud-brick houses with sewage dumped in the rivers. The HangGang would resemble the Ganges. The idea that high living standards elsewhere degrade living standards in developing countries is not supported by evidence.
Pollution rates tend to decline with the rising of an economy, which would suggest that increasing world trade would ultimately result in less pollution as countries become more developed. So by not "supporting" the high standards of living in the developed world, a country themselves wouldn't be able to progress to a developed state. South Korea, achieved their economic successes starting in the late 1970s when they were definitely not a developed country. They sold heavy industrial goods and then ventured into electronics and cars which gave them the economic activity necessary to become one of the most developed countries in the world. The absolute poverty rate in the 1950s was almost 50%. As of 2001, absolute poverty in Korea was less than 2%. It could be argued that without "enabling the high living standards in the developed world," South Korea would still be dumping raw sewage into rivers.
[1] https://www.weforum.org/agenda/2015/06/which-is-the-worlds-m...