11.   They come from a wide variety of sources, including diesel vehicles, wood fires and construction.

12.   While those in California and Arizona are thinking about how to get rid of diesel vehicles, the federal government is encouraging people to go diesel.

13.   And most of that has been blamed on diesel vehicles, such as buses and taxis.

14.   Hong Kong has a large number of diesel vehicles, mostly taxis and light buses, that emit high levels of harmful particles.

15.   Low winds and still air meant that nitrogen dioxide and other emissions from diesel vehicles stayed in the air, contributing to the pollution, a government statement said.

16.   Might diesel vehicles be purifying the air in cities like Los Angeles?

17.   The most practical way to clean up the air, Law added, would be to reduce dependence on diesel vehicles by expanding the railway system.

18.   Tse blamed the poor air quality on high levels of nitrogen dioxide and respirable particulates disgorged by diesel vehicles and an absence of wind to blow them away.

19.   The automakers and the state premiers also demanded a quick reduction in the tax on diesel vehicles.