India probably, or just generically "the third world"

But USA is also failing, Los Angeles was the city with most dense pollution.

https://www.forbes.com/sites/jamesconca/2018/08/23/the-ten-most-polluted-cities-on-earth/

"Los Angeles is the most toxic city in America, the tenth in the world, with the 7th highest PM10 air pollution levels at 57 PM10, and a light pollution score of 10,900 μcd/m2. Chicago and New York ranked in 21st and 26th place, respectively."

And I think things went worse in 2023.

Ok, I found this: https://www.iqair.com/world-air-quality-ranking
Seem China still on all top.

Who is "we" exactly? Most developed countries have reduced their emissions so much that they've been producing less CO2 per Capita than China for a very long time (like, a decade for the whole of the EU if I remember correctly).

https://ourworldindata.org/grapher/consumption-co2-per-capita-vs-gdppc?zoomToSelection=true&endpointsOnly=1&time=earliest..latest&country=CYP~DNK~FIN~FRA~DEU~ITA~NLD~POL~PRT~SVK~ESP~SWE~GBR~CHN~JPN~USA

And I see you coming, no, it's not because China exports lots of stuff for the rest of the world: https://ourworldindata.org/grapher/production-vs-consumption-co2-emissions?country=CHN~OWID_EU27