An extended cold snap, with overnight lows in the 20s, means it’s a good time to check on elderly or otherwise vulnerable relatives and neighbors. Shasta County Public Health is warning about the danger of carbon monoxide, an invisible, odorless, colorless and difficult to detect gas that can kill without warning. Carbon monoxide is created by burning wood or fossil fuels, such as heating and cooking equipment or vehicles left running in closed areas. Early indications can include nausea, headache and drowsiness. Homes should not be heated by gas stoves or ovens, charcoal grills, lanterns or portable camp stoves. Extreme cold can also be deadly. Warning signs of hypothermia can include shivering, exhaustion, confusion, fumbling hands, memory loss, slurred speech or drowsiness. More life saving information can be found at shastahhsa.net or shastaready.org.