moshun is 47 years old.a was transformed very a largely agricultural society to an industrial powerhouse. millions of people were lifted out of poverty. but the sky went dark in the process. was it like this when you were a child? >> it was different, very different. we did have blue sky. and i learned my swimming in the nearby river. but now, you know, we lost the blue sky and much of the clean water. >> how did china lose its blue sky? >> 35 years of massive industrialization. it's very much coal-based energy. and pollution intensive. >> mashun said inhaling the dirty air is a lot like inhaling cigarette smoke. he took me to a store, the clean air center, specializes in masks, and other devices to protect families from the pollution. of all the things we've seen, this one bothers me the most. a baby sized little gas mask. and this is for what age? for like a 1-year-old, 2-year-old? >> under 3. >> under 3. >> china's now setting higher and higher targets for the switch to renewable fuels and decommissioning