One of the highest emitters in recent years was the Cadereyta refinery, run by Mexico’s state-owned oil company Petróleos Mexicanos (Pemex). The plant can also be seen from satellites in space as one of the biggest emitters in the world of sulphur dioxide, which contributes to smog.

Ironically, whether they know it or not, a refinery with such high sulphur dioxide emissions is actually countering climate change by cooling the Earth…