1.   Cars and buses spewing clouds of exhaust are common on the roads, and most electricity is generated by coal-burning plants.

2.   The caves also might be targeted by little-used fuel-air explosives, which can spew a cloud of aerosolized fuel.

3.   Through the years it occasionally has spewed clouds of sulfur dioxide, and it is thought to be responsible for high levels of dust.

4.   A barge hit a bridge on the Intracoastal Waterway on Thursday, spewing a cloud of flammable gas and forcing hundreds of residents and workers to evacuate.

5.   A volcano on the Caribbean island of Montserrat spewed clouds of ash as far away as Puerto Rico, forcing airlines to cancel flights in the region.

6.   Beyond all of that, diesel trucks and cars using inferior gas spew clouds of carbon monoxide and lead-laced exhaust.

7.   Even on their first day on the road, the scavenged engines generally spew clouds of exhaust.

8.   It began spewing thick clouds of roiling ash on Wednesday.

9.   It will no longer spew clouds of black exhaust, and gone is the raucous rattle from which it got its name.

10.   On Thursday, the volcano again spewed small clouds of rock, ash and gas.