Question: I wanted to write in hopes that you will remind readers how dangerous portable generators are when not used properly. Already this winter, three people in New England have died due to carbon monoxide poisoning because they were running unventilated generators after last month's ice storm. Please remind people to be safe! -- Jack in Concord, N.H.

Answer: Many thanks for the heads-up, Jack! Portable generators are just one item that produces carbon monoxide. Other appliances that can be a problem are home furnaces and fireplaces -- basically, any device that uses combustion to produce heat, because that item also produces exhaust. Even worse, carbon monoxide (CO) is colorless and odorless, and CO poisoning can happen very quickly. So how does one prevent being overcome by CO? The best defense is a carbon monoxide detector with a battery backup, placed near sleeping or living areas of your home. This inexpensive item will detect dangerous CO levels before they can affect a home's residents. Like a smoke detector, it should be tested monthly and the battery replaced at least once a year. The second best defense is properly installed and vented appliances that are maintained regularly. Third, read the instructions before using any combustion-based appliance, like a heater or generator. Never use charcoal grills indoors. Never run generators indoors. Don't run the car in a closed garage. Finally, if the CO detector goes off or you or others begin experiencing the symptoms of initial CO poisoning -- dizziness, headache, fatigue, nausea, irregular breathing -- get everyone, including pets, out of the house immediately and contact emergency services.