By daybreak in this sprawling metropolis in southeastern China, residents near thoroughfares who leave their windows open overnight find their faces stiff with a dark layer of diesel soot.
After Mary Leung opens her tiny open-air shop along a major road soon after dawn, she must wipe the soot off her countertops and tables; the tiny yellow-and-olive bird that has kept her company is harder to clean.
Trucks are the mules of this country’s spectacularly expanding economy — ubiquitous and essential, yet highly noxious.