1.   Much of the pollution comes from poorly maintained trucks and buses, which can often be seen belching clouds of black smoke.

2.   The commercials open with menacing smokestacks belching black clouds and move to images of sylvan lakes and gliding canoes.

3.   To reach his home, crowds surged past the ambling donkey carts, the overflowing orange garbage bins and vehicles that belched clouds of exhaust.

4.   Old buses and cars belch clouds of black smoke past beggars, who grab at your arm.

5.   A volcano belched a cloud of ash over the tiny Caribbean island of Montserrat, blanketing the main town and sending jitters through the population, residents said.