A citizen rides in smog on December 20, 2016 in Jinan, Shandong Province of China. Air quality index (AQI) readings exceeded 400 and some schools have suspended classes in Jinan. (Photo by VCG/VCG via Getty Images)

A girl peeps at a gate as primary school students enter to attend an open air class near their school building as part of an initiative from the government following restrictions imposed to control the spread of the Covid-19 coronavirus, in Kolkata on February 7, 2022. (Photo by Dibyangshu Sarkar/AFP Photo)