Perhaps the saddest losses that have come in the aftermath of Sandy are the deaths caused by carbon monoxide poisoning.

In a pattern familiar to emergency management officials, people trying to stay warm without electrical power turn to generators, fireplaces, charcoal grills and other heat sources. Too often, these people fall victim to poor ventilation and carbon monoxide, a silent, odorless killer.

In New Jersey, at least five people died from carbon monoxide poisoning in the early days following the storm. Dozens of others were sickened by exposure to the gas.

A 55-year-old New Brunswick man was killed by the fumes from a generator he had running in his basement. In Edison, a man was poisoned by the exhaust from a generator in his garage.

Authorities warn that generators should never be operated in any enclosed space, even with doors and windows open, or within 20 feet of your home - or a neighbor's home.

Two 19-year-old Newark women died last week when carbon monoxide from an outside generator seeped through their apartment window.

"You need to understand which way the wind is blowing and which way exhaust gases are going to be blown, which isn't an easy thing to do," Rob Aiers of carbonmonoxidekills.com told The Star-Ledger.

And no one should operate a generator or any other supplemental heating source without a carbon monoxide detector with battery backup.

When it doesn't kill, carbon monoxide can still have lasting consequences. The gas binds to hemoglobin in blood, and can prevent red blood cells from sending oxygen throughout the body. Short-term exposure can cause headaches, dizziness and stomach upset. Longer exposure can cause permanent damage - tremors, weakness, confusion and paranoia.

Aside from generators, carbon monoxide can come from using stoves or ovens for heat or from burning anything indoors, including fires in grills or in fireplaces with blocked or faulty flues. Those sources also add to the danger of home fires, just as candles do.

Dr. Steven Marcus of the New Jersey Poison Information and Education System told USA Today his group has gotten more than 46 calls concerning carbon monoxide since Sandy hit, almost double the number of calls the system receives in an average month. The poison information system has also received 63 calls since Oct. 27 concerning people who were sickened while siphoning gasoline, the primary fuel for most generators.

Recent storms and the extended power outages that often follow them have encouraged many area residents to buy generators. That purchase comes with the responsibility to learn to use this equipment properly.