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Safety's No Accident: A New Year's Resolution Has Us Buzzing about Alarms and Detectors – Part 2: Dual-Sensor Alarms

As I reported in an earlier blog, I planned to install sealed 10-year smoke alarms in our home to be in compliance with Maryland state law. I knew that I had replaced a battery-powered smoke in my home within the past 10 years. Further, also I knew that because it did not have a sealed 10-year battery, the alarm would now have to be upgraded. But as I assessed the situation, I learned two things: First, each floor of our home has been hard-wired to the electrical panel for smoke alarms. The battery-powered smoke alarm I had replaced appears to have been installed by the former owner when for some reason, they did not replace the hard-wired alarm on the second floor of our home. Second, because our home was built after 1975, I would need to replace the hard-wired alarm to be in full compliance with Maryland state law. But what alarm should I install?

Different Types of Smoke Detectors

Smoke alarms can come with two different types of smoke detectors.

  • Ionization detectors create a flow of ions within the device. When the ions are disrupted by smoke, the alarm sounds. Research has found that ionization sensors are best at responding to fast-burning, “flaming” fires.
  • Photoelectric detectors have a light source within the device. When the light is reflected by smoke particles entering the chamber, the light sensor triggers the alarm. Research has found that photoelectric sensors are best at responding to slow-burning, “smoldering” fires.

As recently as 2012, about 90% of U.S. homes had a smoke alarm with an ionization sensor, about 5% had a photoelectric sensor, and the remainder of homes had no smoke alarm at all. Having no alarm certainly poses the highest risk, but people are now realizing that having the “wrong” type of sensor in the home can also have tragic results. Today, many groups including the National Fire Protection Association (NFPA), insurers, and the publishers of Consumer Reports recommend installing both types of alarms in our homes. Manufacturers are now selling devices that have both sensors, so the most efficient way to put both sensors in a home is to install these “dual-sensor” models.

Are We Safer with Dual-Sensor Alarms?

Some observers have questioned whether the dual-sensor models will alarm as quickly as models with the individual sensors. However, a 2009 study by the National Institute of Standards and Technology (NIST) and reviewed by NFPA found that “the assumption that sensors in dual alarms are always less sensitive than those found in individual photoelectric or ionization alarms is false. Typically, dual alarms respond before ionization alarms in smoldering fires and before photoelectric alarms in flaming fires.”

Knowing that a dual sensor would effectively protect my family’s safety, I started thinking more about the idea of having just one alarm per story in our home.1 I had seen smoke alarms sold in combination with carbon monoxide (CO) detectors. Could a single alarm on the second floor address the risks of both fires and carbon monoxide poisoning? Unfortunately, the marketplace is not there just yet. Consumer Reports says it well: “Our challenge to manufacturers: Produce a single device that senses both kinds of fire and CO. Until then, combining various types of alarms offers the best protection.”

Next Steps in the Resolution for Home Safety

With this information in hand, I went ahead with purchasing and installing a dual-sensor hard-wired smoke alarm. I also decided to seize the moment and practice what my organization preaches: Every home should have a CO detector installed. In a separate blog, I’ll discuss my search for the optimal CO detector for our home.

1 We have a relatively small home with all bedrooms next to our second floor smoke alarm. Fire officials recommend placing extra smoke alarms within bedrooms if there is a risk that a hallway-based alarm might not be heard in those rooms.  

Jonathan Wilson, MPP, joined NCHH in 1993 and currently serves as Deputy Director and Chief Financial Officer. Mr. Wilson has authored more than 25 peer-reviewed research manuscripts evaluating assessment tools and interventions for healthy housing hazards. He also served as the NCHH representative to the federal Advisory Committee on Childhood Lead Poisoning Prevention from 2004 to 2010. He came to NCHH with a background in nonprofit housing development and a Master of Public Policy degree.

Safety's No Accident: A New Year's Resolution Has Us Buzzing about Alarms and Detectors

This past weekend, I began a home project that would improve the safety of our home, make our home compliant with Maryland state law, and achieve a New Year’s resolution. The project was going to involve 10-year sealed battery smoke alarms. As I’ll explain in a series of future blogs, the home project ended up having a couple of twists and turns, as often happens with DIY work. But rest assured, in less than half a day, my home is now safer and in compliance with the law. Resolution met, with three blog stories to write instead of one. The following is the blog story I expected to write.

Smoke Alarms Save Lives

The evidence is clear. Yet, what is also clear is that even though our fire departments remind us twice a year to check our smoke alarm batteries when we change our clocks, this does not always happen.

Several years ago, I had the opportunity to work on an important study. The National Center for Healthy Housing (NCHH) partnered with the CDC National Center for Injury Prevention and Control to assess the effectiveness of a program to distribute and install battery-powered smoke alarms nationwide. In a report released in 2008, we found that, 8-10 years after installation, only about one-third of the smoke alarms were still operational. Thirty percent (30%) of the smoke alarms were present, but the battery was missing or dead.

Smoke Alarm Recommendations

To address this significant problem, we recommended in the Journal of Community Health (October 2010) that:

  • Future distribution programs install lithium battery-powered alarms with sealed-in batteries that last 10 years. 
  • Alarms come with “hush” buttons that allow residents to silence a nuisance (e.g., burned toast) alarm without removing the batteries or the whole alarm. 
  • Ten-year smoke alarms “chirp” after the battery loses power and offer the added benefit of reminding owners to replace ineffective units at their properties. 
Smoke detection sensors also lose effectiveness after about a decade; fire safety advocacy groups like the National Fire Protection Association have been educating people to replace their smoke alarms every 10 years

New Smoke Detector Laws

Eight states and at least six localities now require homes with battery-powered smoke alarms to install the 10-year sealed-battery units. The states include California, Georgia, Florida, Louisiana, North Carolina, Oregon, and Wisconsin (multifamily only), as well as my home state of Maryland. New York City is one of the localities that currently has a similar ordinance, while New York State is working on regulations that will go into effect in 2019. On January 1, 2018, the Maryland law went into full effect, so smoke alarms with replaceable batteries should now be replaced with 10-year sealed devices.

As with many laws, the devil is in the details. For example, Oregon’s law applies to only one type of smoke detection sensor (ionization), while multiple states exempt battery-powered smoke alarms from the 10-year sealed battery requirement if the alarm connects with other alarms in the home wirelessly (e.g., a Nest). Those planning on buying a battery-powered smoke alarm should look into the requirements in their area

I ended up installing a hardwired smoke alarm in my home (more on that later). Even though I didn’t purchase a battery-powered smoke alarm, I’m so glad the CDC/NCHH research on these alarms is being translated into policy that is making the public safer. Other states and municipalities should consider taking up this important legislation.

Jonathan Wilson, MPP, joined NCHH in 1993 and currently serves as Deputy Director and Chief Financial Officer. Mr. Wilson has authored more than 25 peer-reviewed research manuscripts evaluating assessment tools and interventions for healthy housing hazards. He also served as the NCHH representative to the federal Advisory Committee on Childhood Lead Poisoning Prevention from 2004 to 2010. He came to NCHH with a background in nonprofit housing development and a Master of Public Policy degree.

Hot Tips to Protect Your Home from Fires

We’ve all heard the phrase “where there’s smoke, there’s fire” at least once in our lives. Most of the time, that smoke is the only unfortunate warning we get before we realize something’s wrong. It’s easy to go through your home and make sure matches and lighters are put away and clothes aren’t near a space heater and then call it a day, but it takes a bit more diligence and work to protect your home from fires.

1.    Check Your Cords

Remember the episode of Friends when Rachel left her hair straightener plugged in and accidentally burned down Phoebe’s apartment? It’s true that leaving your electronics plugged in for a while can start a fire, but the same is true for faulty or deteriorating cords for those electronics. If the plastic covering on a cord is broken and the wires underneath are exposed, it could send sparks flying and start a fire. Make it a habit to check all of your electrical cords; if they’re frayed or broken, consider buying a new item to replace the potential danger. You can also use electrical tape (if the break is not extremely bad) as a temporary solution until you’re able to replace the cord. Also make it a habit to check your outlets to make sure they’re not overloaded. If you have to use an outlet for more than two plugs, use a power strip or surge protector. 

2.    Clean the Oven

Almost every movie and TV show we’ve seen shows fires always starting in the kitchen. Ovens, toasters, microwaves, and even the refrigerator can be potential sources for a fire. Keeping everything clean and free of debris will lessen the risk of starting a fire. If you use pot holders, towels, or paper towels in the kitchen, keep them clear of the oven burners so they don’t catch fire. Cleaning your stovetop and oven to prevent or get rid of the grease buildup also makes it harder to fires to start spontaneously. Lastly, always check the kitchen appliances before you go to bed: make sure all burners are switched off and unplug toasters and toaster ovens if you won’t be using them. Make sure that you also have an unexpired fire extinguisher near the kitchen, preferably one that is designed to put out grease fires. 

3.    Keep an Eye on Your Candles

Candles are some of the most useful home accessories: They can light a dark area, fill a room with delicious fragrance, and even serve as a prop for telling spooky stories. At the same time, candles are some of the most dangerous home accessories. You should never leave a candle unattended, especially when there are children around. Don’t leave candles burning around loose fabrics like curtains or clothes, and always extinguish the candles when you’re finished with them. Rest candles on a sturdy surface that won’t fall over. If you absolutely have to leave a candle (maybe you need to step into another room, for example), move the candle to a tall and safe space where it won’t be at risk of falling or being bothered.

4.    Avoid Smoking in the House

As tempting as it may be, it’s really a good idea to take your cigarettes outside if you must smoke. You’ve no doubt heard stories about people falling asleep with lit cigarettes, which is obviously very dangerous. On a related note, you don’t want to leave cigarettes, matches, and lighters around the house where kids can get to them.

5.    Stack Your Firewood Correctly

A wood-burning fireplace can be quite cozy in the winter time, but if you aren’t careful, it can also be dangerous. You’ll want to avoid embers flying out onto your carpet, which can be done by stacking wood correctly. If you stack your wood as you would a bonfire, you can reduce your chances of embers popping out into your living room. Also, if you burn pine, hemlock, or other evergreen wood species, have your chimney cleaned regularly. These wood types contain more tar, which can result in a creosote buildup in your chimney. Never operate a fireplace without a screen, and never leave a fire unattended.

6.    Clear the Flammable Debris

Wildfires are just as dangerous as a kitchen fire, depending on where you live. Dry brush and sweltering heat is just enough to cause a massive outdoor blaze. You can protect your home by clearing out dead branches and leaves from around the outside perimeters and composting them instead of burning them. If you have trees around your home, trim any branches that look dead and are hanging over the house to prevent a flame from dropping onto your roof. If you have firewood by your back door, consider moving the piles away from house once the hotter months start coming back. Firewood piles can easily catch a spark and go up in flames, and a pile of lit firewood by your home can mean disaster or the need for major restorations.

7.    Get the Proper Smoke Detectors and Replace Them Every 10 Years

It goes without saying that you should have smoke detectors in your home, but many people assume that they’re all basically the same. Smoke detectors with photoelectric sensors are faster to respond to smoldering fires and are recommended by the International Association of Fire Fighters. Ionization detectors are better suited for flash fires; however, they’re more likely to alarm for non-life-threatening situations such as burnt toast. This can be a disadvantage of the dual-sensor detectors as well. The National Fire Protection Association (NFPA) recommends installing both ionization and photoelectric alarms in your home for the best overall protection from both sudden and smoldering fires. If you’ve decided to replace your ionization detector for a photoelectric model, don’t discard a working smoke detector until you have and are ready to install its replacement. Having a working detector is more important than having a specific variety.

While we're talking about smoke detectors, the best protection comes from having a smoke detector with a 10-year battery, and from replacing that smoke detector after 10 years. It’s may seem inconvenient, but it’s worth it to keep your family safe.

The good news is that it’s not difficult to keep your home safe from fires. You just need to be aware of the dangers and take the appropriate precautions.

Patricia Sarmiento loves swimming and running. She channels her love of fitness and wellness into blogging about health and health-related topics at She played sports in high school and college and continues to make living an active lifestyle a goal for her and her family. She lives with her husband, two children, and their shih tzu in Maryland.

Photo by tpsdave via Pixabay.

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