Swimming Pools Good, Guns Bad

A number of gun advocates use bad statistics and logic to conclude that swimming pools are more dangerous than guns. They make a number of logical mistakes, such as only looking at accidental shootings or focusing on children and thereby deliberately ignoring the adults who are much more likely to be shot and less likely to drown in a swimming pool. Leaving those arguments aside, however, there is another reason they are fundamentally wrong – the health benefits of a swimming pool dwarf the risks, providing around an order of magnitude more lifespan increase via exercise than they claim due to drowning accidents, if not more.

390 children per year under the age of 15 drowned in the nation’s approximately 10.7 million swimming pools between 2009 and 2012. Note that this data is substantially different that the data from 1997 used in the Levitt article cited above (550, 6 million), so we clearly have experienced a dramatically falling death rate the last 15-20 years. I suspect you can blame regulations for that. In any case, data on teens or adults is sparse but the trend of death rates falling rapidly with age clearly continues, at least until very old age. Let's approximate it at 450 total drowning per year in recent years, which works out to one death per 23,778 pools.

Sadly, the average age of the drowning victims – two-thirds are between one and three years old – is very low, so let’s approximate the average as five years. Compared to an eighty year lifespan, this represents 75 years of lost life per 23,778 pools per year. Therefore, the average pool claims 1.15 life-days (or 28 life-hours) each year due to drownings.

So how does this stack up against the exercise benefits? In short, this risk is dwarfed by them. For example, this paper indicates (summary here), that meeting the CDC guidelines of 2.5 hours of moderate exercise (such as playing in a pool) per week extends lifespan by a whopping 3.4 years. If you work through the math on that, you will find that for each hour of moderate exercise, your lifespan is increasing by two hours and fifty minutes, almost three times as much! Vigorous exercise is even better, close to a six to one ratio. This data was specifically for those aged over 40, but it is highly likely that something similar applies to younger people as well.

So assuming that swimming in a residential pool meets the paper’s definition of moderate exercise, which is certainly seems to, and that the benefits of exercise are roughly constant with respect to age, then if a pool generates a mere 10.4 hours of additional moderate exercise per year, it will save more life-days than it will take. While I don’t have any firm data on how many person-hours a typical pool represents each year, surely it is far, far higher than 10.4, probably closer to several hundred, and many thousands for public pools. Clearly, the health benefits win in a landslide, and the net effect of owning a pool is to cause your family members to live substantially longer, not less.

So while pools are risky, they are far less risky than the alternative – your kids sitting around in front of the TV growing fat. Obviously, one should take the risks of pools seriously, follow all relevant regulations, and otherwise act prudently, but getting your kids a pool is ten steps forward for every one back.

In contrast, guns do not have any health benefits that would offset the incredible risks that they bring to bear on your family. To compare them to pools, which are a substantial net positive from a health and longevity perspective, is therefore completely mistaken. Guns do not lower your cholesterol, or prevent heart attacks, or make your sex life better. They just get you and your family members killed, both by dramatically increasing suicide rates in your home, and turning what would have been merely heated arguments into fatal tragedies. If you love your family, you'd sell your guns for scrap today, and use the money to buy a pool.

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Addendum: The same logic works for cycling. Others have worked out the math here. Exercise is your friend, folks.

Guns, Booze, and Automobiles

A comment I often hear from gun advocates is a variant of "Why don't we restrict access to cars and alcohol, as they get a lot of innocent people killed as well?".

This is actually a good argument, qualititatively. Where it breaks down is quantitatively. In other words, the numbers just don't add up. I have posted the wonky details here, but what I have calculated or discovered is that:

Americans make 233 automobile trips per year, killing approximately 21500 third parties, or 10.7 million trips per third party fatality.

Americans drink approximately 28 billion times per year, killing approximately 7400 third parties, or 3.7 million drinking events per third party fatality.

Americans use long guns (rifles, shotguns, etc) approximately 840 million times per year, resulting in 950 third party fatalities, or one fatality per 1.15 million uses.

Americans use handguns approximately 500 million times per year, resulting in over 7600 third party fatalities, or about one fatality per 67,000 uses.

It is very clear what item stands out here: handguns. Long guns seem to be only marginally more dangerous than drinking or driving, and probably safer than drinking AND driving. However, handguns are in a league of their own, with well over a hundred times the third party fatalities per use as automobiles and around fifty times the fatalities per use as alcohol. This is why they are not remotely compariable, and why is it perfectly reasonable to call for the abolition of handguns, but not necessarily long guns.

Guns, Booze, and Automobiles - Wonk Version

This is the wonky details of my post found here for those who like to quibble.

Note that throughout this exercise, I have focused on "externalized" fatalities: deaths to parties other than the drinker, the driver, and the gun owner. Matters such as suicide, single-car auto accidents, etc are excluded or explicitly accounted for. While obviously these are still a matter of public policy, they are on a different level than harm inflicted upon innocent third parties.

For automobiles, there are approximately 233 billion trips made per year in the US, and bit over 32000 traffic fatalities. However, roughly a third are self-inflicted and only involve the driver. This can be inferred from the facts that about half of all fatalities occur to a driver and that about a third of fatal accidents are single car, thus implying that roughly two thirds of the half of fatalities that occurs among drivers happens to the at-fault driver, while the other third of a half occurs to an innocent driver in a two car accident. Thus, there are approximately 21500 externalited traffic fatalities each year. This leads to the conclusion that with respect to driving there are approximately 10.7 million trips per externalized fatality.

For drinking, the average American drinks 9.4 liters of alcohol per year. If you assume that the average drinking session involves three ounces of alcohol (about three drinks), that implies the average American drinks 88 times per year, or 28 billion drinking events per year among all Americans. There were 10228 drunk-driving related fatalities in 2010, but approximately 45% of them are likely self-inflicted, resulting in 5625 externalized drunk driving fatalities. Additionally, approximately 28% of violent crime is alcohol related. There were 12664 homocides in 2011, and assigning 50% of the responsibility of "alcohol related" homocides to the alcohol results in 1773 externalized deaths. Combined with the traffic fatalities, this gives alcohol a total of 7398 externalized fatalities, or approximately one externalized fatality per 3.7 million drinking events.

The data for guns is a little more sparse and I have to make some assumptions. One is to look at ammunition use. The domestic ammunition market is $1.9 billion dollars per year according to a recent industry report. At $0.20 per bullet wholesale, that is 9.5 billion bullets. Of those, the military uses 1.8 billion, and other federal agencies 400 million. I could not find data for state and local police use, but considering there are more than five times as many state and local law enforcement officers as federal ones, my assumption that their bullet consumption is the same at 400 million is probably conservative. Thus, there are approximately 6.9 billion bullets available for civilian use annually. For a rough estimate, the assumption that people shoot six bullets on average when using a gun would lead to 1.15 billion uses per year. Of course, "using" a gun could range from no shots fired (an unsuccessful hunt, brandishing it in order to scare off an intruder) to a few boxes full at the gun range. The figure of six per use is literally made up but probably reasonable. Note that since there are about 64 million gun owners in the US, this would imply the average gun owner uses a gun 18 times per year and expends and annual total of 110 bullets. That seems very reasonable to me based on my experience.

We can attempt to look at this from the bottom up as well. There are 13.7 million active hunters in the US. Assuming 30 hunts per year, that is approximately 400 million hunts. As for shooting ranges, their annual industry revenue is about $560 million, so at $30 per trip, there are about 19 million visits to gun ranges. However, these would disproportionally add up to a lot of bullets fired, as most people shoot a fair number each time they are there. Even the wildest estimate of defensive gun uses is 2.5 million per year. Assuming the average gun owner uses their guns about ten times a year in addition to the aforementioned uses puts us right back at about 1.1 billion uses. To be generous, I will overweight the (likely exaggerated) defensive use estimate 100-fold, just for good measure, resulting in 1.35 billion gun uses per year.

Hand guns make up a bit under one third of all guns in the US. I will assume they make up no portion of the hunting uses, 80% of the 100-fold overweighted defensive uses, and a proporitionate 1/3 of the remaining miscellaneous uses, resulting in 510 million uses per year, with the remaining 840 million uses being long guns (rifles, shotguns, etc). According to the FBI, there were 8583 firearm deaths in 2011, with 6220 from handguns, 776 from long guns, and 1587 from "unstated". Assigning the "unstated" deaths to handguns and long guns proportionately, this results in 7631 hand-gun deaths and and 952 long-gun deaths in 2011. Thus, 1.15 million uses per externalized fatality for long guns, and 67200 hand gun uses for externalized fatality.