With the changing of the seasons, Utah's annual "Red Light-Green Light" program to control air pollution has resumed.

This year, it begins a few days earlier than past years, according to the Utah Division of Air Quality. Normally, the program begins on Nov. 1, but this year, it is already in effect.

The program is designed to reduce emissions from fireplaces, wood stoves and vehicles during air inversions, when a cold layer of air tends to trap warm pollution in valleys.

During green conditions, no restrictions are in place. When conditions are deemed yellow, the public as asked to voluntarily curtail emissions. During red conditions, when pollution nears the danger level of 35 micrograms per cubic meter, a mandatory no-burning rule is imposed.

Fines can be imposed on offenders.

"This program has been absolutely crucial for Utah to meet air quality standards in the winter," said Cheryl Heying, director of the division. "It's even more crucial with tougher federal requirements that cut in half the allowable daily average of fine particulate pollution caused by combustion."