There are many brands of smoke alarms on the market, but they fall under two basic types: ionization and photoelectric.

Ionization and photoelectric smoke alarms detect different types of fires. Since no one can predict what type of fire might start in their home, the USFA recommends that every home and place where people sleep have:

• Both ionization AND photoelectric smoke alarms. OR

• Dual sensor smoke alarms, which contain both ionization and photoelectric smoke sensors.

Choose interconnected smoke alarms, so when one sounds, they all sound.

There are also alarms for people with hearing loss. These alarms may have strobe lights that flash and/or vibrate to alert those who are unable to hear standard smoke alarms when they sound.

Smoke alarms are not expensive and are worth the lives they can help save.

Alarm type and cost

• Ionization and photoelectric: $6 and up

• Dual sensor: $24 and up

• Smoke alarms with a microprocessor (faster to alert, fewer false alarms): $30 and up

• Radio frequency/wireless (communicate from one to the next without wires): $40 and up

Your city, county or state may require a specific type of alarm. Please check with your local fire marshal for information on what type of alarm you need.

Some fire departments offer reduced-price, or even free, smoke alarms. Contact your local fire department's non-emergency phone number for more information.

Smoke alarms are powered by battery or by your home's electrical system. If the smoke alarm is powered by battery, it runs on either a disposable nine-volt battery or a non-replaceable 10-year lithium (“long-life”) battery. Alarms that get power from your home's electrical system, or “hardwired,” usually have a back-up battery that will need to be replaced once a year.

• A closed door may slow the spread of smoke, heat and fire. Put smoke alarms inside and outside each bedroom and sleeping area. Put alarms on every level of the home. Smoke alarms should be interconnected. When one sounds, they all sound.

• Place smoke alarms on the ceiling or high on the wall. Check the manufacturer's instructions for the best place for your alarm.

• Only qualified electricians should install hardwired smoke alarms.

Some fire departments will install battery-operated smoke alarms in your home at no cost. Contact your local fire department’s non-emergency phone number for more information.

Is your smoke alarm still working? A smoke alarm with a dead or missing battery is the same as having no smoke alarm at all. A smoke alarm only works when it is properly installed and regularly tested. Take care of your smoke alarms according to the manufacturer’s instructions. Below are some general maintenance tips.

Smoke alarm powered by a nine-volt battery

• Test the alarm monthly.

• Replace the batteries at least once every year.

• Replace the entire smoke alarm every 10 years.

Smoke alarm powered by a 10-year lithium (or “long-life”) battery

• Test the alarm monthly.

• Since you cannot (and should not) replace the lithium battery, replace the entire smoke alarm according to the manufacturer's instructions.

Smoke alarm that is hardwired into your home's electrical system

• Test the alarm monthly.

• Replace the backup battery at least once every year.

• Replace the entire smoke alarm every 10 years.

Never take the battery out of your smoke alarm while cooking! If a smoke alarm sounds while you're cooking or taking a shower with lots of steam, do not remove the battery. You should:

• Open a window or door and press the “hush” button.

• Wave a towel at the alarm to clear the air.

• Move the entire alarm several feet away from the kitchen or bathroom.

Disabling a smoke alarm or removing the battery can be a deadly mistake.

Carbon monoxide, also known as CO, is called the “Invisible Killer” because it's a colorless, odorless, poisonous gas. More than 150 people in the Unites States die every year from accidental non fire-related CO poisoning associated with consumer products, including generators. Other products include faulty, improperly-used or incorrectly-vented fuel-burning appliances such as furnaces, stoves, water heaters and fireplaces. Source: Consumer Product Safety Commission

Because CO is odorless, colorless, and otherwise undetectable to the human senses, people may not know that they are being exposed. The initial symptoms of low to moderate CO poisoning are similar to the flu (but without the fever). They include:

• Headache

• Fatigue

• Shortness of breath

• Nausea

• Dizziness

High level CO poisoning results in progressively more severe symptoms, including:

• Mental confusion

• Vomiting

• Loss of muscular coordination

• Loss of consciousness

• Ultimately death

CO enters the body through breathing. CO poisoning can be confused with flu symptoms, food poisoning and other illnesses. Some symptoms include shortness of breath, nausea, dizziness, light headedness or headaches. High levels of CO can be fatal, causing death within minutes.

The concentration of CO, measured in parts per million (ppm) is a determining factor in the symptoms for an average, healthy adult.

• 50 ppm: No adverse effects with 8 hours of exposure.

• 200 ppm: Mild headache after 2-3 hours of exposure.

• 400 ppm: Headache and nausea after 1-2 hours of exposure.

• 800 ppm: Headache, nausea, and dizziness after 45 minutes; collapse and unconsciousness after 1 hour of exposure.

• 1,000 ppm: Loss of consciousness after 1 hour of exposure.

• 1,600 ppm: Headache, nausea, and dizziness after 20 minutes of exposure.

• 3,200 ppm: Headache, nausea, and dizziness after 5-10 minutes; collapse and unconsciousness after 30 minutes of exposure.

• 6,400 ppm: Headache and dizziness after 1-2 minutes; unconsciousness and danger of death after 10-15 minutes of exposure.

• 12,800 ppm: Immediate physiological effects, unconsciousness and danger of death after 1-3 minutes of exposure.

Source: NFPA's Fire Protection Handbook, 20th Edition.