Indoor Air Pollutants: Protect Against Smoke, Carbon Monoxide and Radon

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First Alert’s Ultimate Dual Sensor Remote Control Alarm (SA302)
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The First Alert Strobe Light Smoke Alarm (SB100B) will alert the hearing impaired.
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American Sensor’s CO910 CO alarm features a digital LED display.

The air inside homes can be even more polluted than the outdoor air in the largest and most industrialized cities, according to the U.S. Environmental Protection Agency (EPA). Some air pollutants, such as cigarette smoke, are easy to detect and avoid. Others, such as carbon monoxide and radon, are virtually impossible to see or smell, and they can be deadly. You can protect your family by installing appropriate alarms.

Smoke alarms

Your chance of surviving a fire is almost 50 percent higher if your home has the recommended number of smoke alarms, according to the National Fire Protection Association (NFPA). Experts recommend installing a smoke alarm on each floor and inside each bedroom. For larger homes, consider interconnecting models, which all sound when one alarm senses smoke. Install alarms near but not inside kitchens, garages and bathrooms to prevent false alarms from cooking smoke, exhaust and humidity.

Ionization alarms use “ions,” or electrically charged particles, to detect smoke. Photoelectric alarms use a beam of light and a light sensor. You need both technologies. Ionization alarms respond to blazes with high flames, and photoelectric alarms respond to slow, smoldering fires. “Dual alarms” can sense both types of fires (high-flaming and smoky) with equal effectiveness.

Choose from battery-powered alarms, hardwired electric models or units you can incorporate into your home’s security system. If you prefer a hardwired model, choose one with a battery backup.

Combination alarms sense both smoke and carbon monoxide. However, these alarms typically include only one type of smoke-detection technology (ionization or photoelectric). If you purchase a combination alarm, make sure to buy a second alarm with the smoke-detection technology not used in the combination alarm.

Whatever model you choose, replace  smoke alarms every 10 years because their sensitivity declines over time. When an alarm’s battery runs out, the alarm will give a short beep every minute or so. However, experts suggest replacing batteries at the same time each year before the low-battery signal begins. Some models include lithium batteries, which typically last the life of the alarm.

Carbon monoxide alarms

Carbon monoxide (CO) is found in the combustion fumes of fuel-burning engines, tools and appliances–from cars and trucks to heating systems and gas ranges. The amount of CO they produce is usually harmless, so long as these devices are working properly and used appropriately. To ensure they are, have your heating system and other indoor, fuel-burning appliances inspected by a qualified technician annually.

Likewise, it’s critical to use fuel-burning tools appropriately. Never operate charcoal grills, portable gas stoves or any other   unvented fuel-burning devices inside your house, garage or any other enclosed or partially enclosed space where fumes can build up quickly.

Carbon monoxide kills roughly 500 people in the United States each year. CO poisoning can occur from brief exposure to very high levels of the gas as well as longer-term exposure to low levels. Breathing in CO can lead to headaches, nausea, dizziness, fatigue, confusion, unconsciousness and death. The gas is invisible and odorless–the only way to detect it is with a CO alarm or by professional inspection. In short, if you have fuel-burning appliances in your home or an attached garage, you should install a CO alarm.

The technology of CO alarms is still a work in progress. In laboratory testing, device performance has varied–some doing well, others failing to alarm even at very high CO levels. When you shop for a CO alarm, don’t choose a product based on cost alone. Underwriters Laboratories (a public service product-testing organization) certification is a must. For larger homes, consider buying interconnecting models, which trigger each other when one detects a threat.

A battery-operated alarm or an electric model with a battery backup is best because people tend to increase their use of appliances, such as fireplaces and generators, during power failures.

Look for a unit with a digital readout, which allows you to monitor levels of CO that are lower than 70 parts per million (ppm)–the amount that triggers most CO alarms.

Finally, a CO alarm can’t ensure 100 percent protection from CO poisoning. It’s also a good idea to follow the safety tips outlined on the Centers for Disease Control’s website

Radon detectors

Radon is an odorless, invisible gas that comes from the natural breakdown of uranium, which exists in small amounts in most soil, rocks and water. The second-leading cause of lung cancer, radon can enter your home through drains, cracks and other holes in the foundation. The good news is that it takes years of radon exposure for lung cancer to become a concern. Moreover, simple tests detect radon and established venting techniques can fix problems.

Nearly 1 out of every 15 homes in the United States has elevated radon levels, the EPA estimates. Testing is the only way to know whether your home has elevated radon levels.

Testing for radon is easy and inexpensive. Radon test kits can cost as little as $10 plus a $15 lab fee and are readily available in hardware stores. You also can hire a radon-mitigation contractor to test your home.

There are many types of radon test kits and detectors. Short-term detectors measure radon levels for 2 to 90 days, depending on the device. Long-term tests determine average concentration levels over a 90-day period or longer. The most common type of short-term kit is a simple charcoal canister, and the most common type of long-term kit is the alpha track detector.

Because radon levels can vary from day to day and month to month, a long-term test is a better indicator of average radon levels.

If your home’s radon level measures 4 pico-curies per liter (pCi/L) or higher, the EPA recommends mitigation. To find a qualified radon service professional, contact the National Environmental Health Association or the National Radon Safety Board (see “Resources” at right).

Smoke alarm basics

• Choose a smoke alarm that features a combination ionization/photoelectric sensor.

• Consider only alarms that meet UL (Underwriters Laboratories) standards. Most, but not all, models do.

• Choose an alarm with a test button to ensure it’s operating correctly.

• Place each alarm at least 4 inches from corners (4 inches from walls if placed on the ceiling, 4 inches from ceiling if placed on the wall) and away from windows and heating vents.

• Maintain alarms. Test them monthly. Replace batteries yearly. Vacuum out dust and other debris (get one with a removable cover for easy cleaning); too much dust can cause a sensor to fail.

• Replace smoke alarms every 10 years.

CO alarm basics

• Have your heating system, water heater and any other gas-, oil- or coal-burning appliances serviced by a qualified technician every year.

• Check or replace the battery in your CO alarm when you change the time on your clocks each spring and fall. If the detector sounds, leave your home immediately and call 911.

• Don’t burn anything in an unvented stove or fireplace.

• Seek prompt medical attention if you suspect CO poisoning and feel dizzy, light-headed or nauseated.

• Don’t use a generator, charcoal grill, camp stove or other gasoline- or charcoal-burning device inside your home, basement or garage, or outside near windows.

• Don’t leave a car or truck running inside a garage attached to your house, even if you leave the garage door open.


Carbon Monoxide Detectors

American Sensors CO920
(800) 387-4219 (Dicon Global)

Kidde Nighthawk KN-COPP-B
(800) 880-6788
(Consumer Reports’ “Best Buy”)

NSI 3000 Monitor
Available through and
(alarm sounds at 15 ppm)

Smoke Alarms

First Alert Dual Sensor SA302 or Strobe Light SA100B
(800) 323-9005

Radon Test Kits

First Alert RD1 Radon Detector
(800) 232-9005

Pro-Lab Radon Gas Test Kit
(954) 384-4446

RadonZone Alpha Track Test Kit
(540) 651-9906


A Citizen’s Guide to Radon
(800) 438-4318 

National Environmental Health Association
(800) 269-4174

National Radon Safety Board
(866) 329-3474

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