Saturday, September 6, 2014

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.


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