Mass shootings and terrorism. These two topics continue to strike fear into the hearts of Americans everywhere.

It makes sense why. Their randomness instills us with fear. The shooters often look deranged, and the images shown in the media are gruesome. And because of the cynical (but true) journalistic maxim, "If it bleeds, it leads," we are guaranteed weeks of discussion after every incident.

But boring things are far deadlier. According to the most recent data from the CDC, accidents killed 136,053 Americans in 2014, making them the #4 leading cause of death1. Included in that number is accidental carbon monoxide poisoning, which kills on average 374 people every single year2. (See chart.)

Source: CDC

Homes that are entirely powered by electricity do not have problems with carbon monoxide. The deadly gas3 is only a potential threat to individuals who heat their homes or appliances with natural gas or some other fossil fuel. Also, during power outages in the winter, some people bring gasoline powered generators inside. That's a particularly bad idea, and it partially explains the spike in carbon monoxide poisonings in the winter.

How Deaths from Carbon Monoxide Compare to Mass Shootings and Terrorism

Because so few people die from it, most of us don't think twice about carbon monoxide. Yet, we all fret over mass shootings and terrorism. So, how do deaths from the former compare to those of the latter?

The numbers are a bit tricky. First of all, the definition of "mass shooting" varies. Starting in 2013, the FBI reduced the definition of "mass murder" from four to three. Mass shootings, on the other hand, can be defined based on the number of victims, deceased or not. Also, it can be difficult to separate mass shootings from terrorism, especially since an increasing number of terrorist attacks involve mass shootings. With these caveats in mind, existing numbers can give us a ballpark estimate.

Given 374 carbon monoxide deaths and a total U.S. population of 319 million, the mortality rate from carbon monoxide poisoning is 1.2 deaths per one million Americans.

According to a 2013 analysis provided by The Economist (see chart on right), the worst year for mass shootings (based on morality rate and defined as "four or more people killed in a single incident and location") in the U.S. was 2012, with a mortality rate just under 0.25 deaths per one million. In other words, the average American is roughly five times more likely to die from accidental carbon monoxide poisoning than in a mass shooting.

If we use a different definition for mass shooting, say a minimum of four injuries and/or fatalities, then 188 Americans were killed in mass shootings in 20154, which gives a mortality rate of 0.59 deaths per one million. Even by this expanded definition, carbon monoxide is still twice as likely to kill the average American than a mass shooting.

Similarly, CNN produced an analysis that showed how many Americans (including those living abroad) died in terrorist attacks. The annual average was around 20. Using a total population figure of 327 million (319 million Americans + 8 million living abroad), the mortality rate from terrorism is a miniscule 0.06 per one million people. Thus, the average American is 20 times likelier to die from carbon monoxide poisoning than by an act of terrorism.

The point isn't to scare people about carbon monoxide. It's a minor threat. Instead, the point is to demonstrate that, once again, the chaotic stuff that makes the nightly news is far less likely to kill you than boring, everyday things. So eat healthy and exercise, buckle your seat belt, stop texting while driving, and put down that cigarette.

Notes

(1) Suicide is in the top 10 (42,773 deaths), and homicide is not in the top 10.

(2) "Weird Al" Yankovic's parents died from carbon monoxide poisoning.

(3) Dr. Josh Bloom explains the chemistry behind the toxicity of carbon monoxide.

(4) It is unclear if this figure includes the shooter himself.

Source: "QuickStats: Number of Deaths Resulting from Unintentional Carbon Monoxide Poisoning, by Month and Year — National Vital Statistics System, United States, 2010–2015." MMWR 66(8): 234. Published: 3-March-2017. DOI: 10.15585/mmwr.mm6608a9