How can awareness of the need for CO sensors be increased?

Public outcries for reducing carbon dioxide (CO₂) emissions to reduce their climate change impact have been widely promoted for more than two decades. However, attention to a more immediate public health problem from carbon monoxide (CO) has not received anywhere near the same level of attention– unless the deaths get news coverage. For example, in May of 2022, three American tourists died in a Sandals resort in the Bahamas from CO poisoning. More recently, a healthy 21-year-old man nearly died when CO gas filled his small apartment.

Known as the silent killer, carbon monoxide is odorless with no visible or audible human means of detecting it. It is a problem in enclosed spaces not outdoors. In fact, according to the US Environmental Protection Agency (EPA), carbon monoxide totals in the air have declined 88% since 1980. However, more people died from accidental carbon monoxide poisoning in 2022 than any year since at least 1999. In addition to the 624 accidental deaths in 2022, 579 people committed suicide bringing the death total due to CO poisoning to 1,244 people in the US. While this number seems small, according to the CDC, more than 100,000 people visit an emergency room every year for accidental carbon monoxide poisoning.

Automobile exhaust in a closed garage is one of primary causes of suicide deaths but exhaust from other combustion sources including grills, heaters, lawn mowers, generators, pressure washers, and more are just as much of an unintentional problem. As a result, CO sensing has been required for homes and offices for many years. The more recent detectors are battery powered and often interface with smart home networks. In addition to product manual warnings to periodically (every 6 months) change the batteries, the CO sensor itself will also alert users to replace the batteries before they are totally dead. What is not as well known is that the sensors in the CO detector also become useless as they reach their end of life that could be 5 to 7 years after being manufactured.

In 2009, Underwriters Laboratories (UL), began requiring an end-of-life warning to alert homeowners when their carbon monoxide alarm reached the end of its useful life. In response, some manufacturers improved their designs to have a 10-year product life. Checking the back of a CO detector should provide either a build date or an expiration date. If there’s no date or the detector is more than seven years old, it should be replaced immediately.

The UL requirement to replace an end-of-life is independent of the technology used in it. Smoke and heat alarms are often combined with CO sensing. Electrochemical sensing appears in the most common type of detector. For this design, electrodes submerged in an electrically conductive, electrolyte, solution have a chemical reaction when carbon monoxide enters compartment that houses the sensor. The amount of the electrical current increase indicates the concentration of the carbon monoxide molecules.

In contrast, metal oxide sensors employ circuitry instead of a chemical solution. When the sensor’s chip is exposed to CO, it lowers the material’s resistance to indicate the concentration of the chemical present in the air.

Finally, some carbon monoxide detectors employ a gel that changes color as it soaks up carbon monoxide. A light sensor tracking the gel’s color indicates the level of carbon monoxide present in the air.

No matter what sensing technique is used, homeowners, renters, and businesses should have properly function CO sensors located as required by the manufacturer and local as well as other government regulations.

References

Bahamas Sandals deaths: what to know about carbon monoxide poisoning, a quiet killer

Is carbon monoxide still a problem in the US?