1.   Craig Ellis, a National Weather Service forecaster, said a high-pressure system that created a temperature inversion in the Valley also traps pollutants in the atmosphere.

2.   Sinking air that accompanies high pressure acts like a tight lid to trap pollutants near the ground.

3.   The sinking air that accompanies high-pressure systems acts like a lid to trap pollutants near ground.

4.   Weather-tight homes trap pollutants inside.

5.   Air pollution could even be reduced, although this mountain-rimmed basin is vulnerable to wintertime temperature inversions that can trap pollutants at ground level.

6.   Elsewhere in the province, illegal coking ovens and paper mills burn coal with no equipment to trap pollutants.

7.   In addition to high temperatures, Tokyo was beset Thursday by a stagnant air pattern which trapped pollutants and created a thick layer of smog.

8.   Mexico City is located in a valley that traps pollutants during the winter months when winds are low.

9.   Scientists chose Salt Lake because its mountain-rimmed basin is vulnerable to weather inversions that trap pollutants near the ground.

10.   They also trap pollutants, prompting health advisories and firewood bans.