1.   But formation usually takes several hours, during which time the air drifts from where the pollution was emitted.

2.   China is highly dependent on coal for generating electricity, which emits extensive pollution.

3.   Emissions of methane and hydrogen sulfide from hog waste, made without any permits to emit air pollution, was another serious concern, he said.

4.   Ford voluntarily builds the Excursion to emit less pollution than regulations allow for sport utilities.

5.   Hybrids, after all, drive as well as gasoline cars because they are, in the main, gasoline cars, and they still emit some pollution.

6.   It remains more expensive than natural gas turbines, but windmills emit no pollution and are not subject to volatile fuel prices.

7.   Other high-temperature fuel cells are made up of an acid base or molten salt, which emit more pollution.

8.   Part of the plan was to use the cells to provide power for the signs instead of buying power from coal-fired generating plants that emit pollution.

9.   The panel is expected to tackle a range of issues, such as the long lines of idling vehicles emitting pollution at border crossings.

10.   The pollution is emitted by cars, power plants, mining smelters and even fast-food restaurants.