As the cooler temperatures roll into the valley, so does the pollution.

The annual winter atmospheric inversion effect, preventing pollutants building up below from escaping, has begun.

This week, the Department of Environmental Quality showed air pollution climbing into “Moderate” levels as the cooler temperatures crept in during morning and evening hours.

Residents using fire places can help reduce pollutants by not burning wood logs, said Ericka Flores with Maricopa County.

“Or, wax logs, on any given day,” Flores implored.  “Instead of burning wood, use alternatives like propane or electric.”

Maricopa County is offering residents in limited areas a chance to retrofit wood burning fire places with cleaner options.

This week, the county begins coordinated efforts with the D.E.Q. posting “No Burn” days as pollutant levels rise.