Winter is risky, even when mild.

• Position: Avoiding carbon monoxide poisoning and hypothermia

Whether winter weather is cold or just cool, the season brings temperatures that require some safety precautions. "You don't have to live in the land of snow and ice to be at risk of suffering from winter weather," explains Robert Norris, assistant professor of surgery and clinical director of the Stanford University Hospital Department of Emergency Services.

Even in mild climates, people use heaters on the coldest days, and he points out that some gas or oil heaters pose a potential risk of carbon monoxide poisoning, which can be life-threatening. Those in mild climates may need to be especially alert, since heating units aren't used as often there and may not receive regular preventive maintenance.

"Carbon monoxide poisoning is caused by inefficient burning of any oil- or gas-burning heater, and early warning signs of this condition are ful-like symptoms, such as headache, nausea, vomiting, or ringing in the ears. But remember--carbon monoxide is odorless and tasteless, so you can't expect to notice its presence in the air."

So, how can you tell carbon monoxide poisoning from the flu? "One warning sign is when the whole family develops symptoms almost simultaneously--not a few...