A year ago we took a trip to London, and hopped over to Paris for 4 days in the middle. While planning the trip (Spring of 2016), the terror attacks in Paris of the previous November were pretty fresh in everyone’s mind. More than one person asked me if I was worried about terrorism. Before worrying, I did the math.
Basically the odds of dying in a terror attack are:
Probability of a terror attack occurring while we’re there
(times)
Probability of dying in such an attack, given that we’re there
Needless to say, it is difficult to assign values to either of these. I just made a bunch of assumptions.
Probability of a terror attack in Paris while we’re there. How frequent are attacks like that? Impossible to say. Let’s pick a “high risk” value and say that Paris will have an attack like that once every three years. That’s a depressing thought, and I don’t think it’s accurate – having suffered the first attack, countries tend to take steps to reduce the odds of another. But let’s go with that. Three years = 1095 days. We were there 4 days, so 4/1095 = 1 in 274.
Probability of dying in an attack. The population of central Paris is about 2.2 million (surrounding area is much larger). Plus, another 43,000 tourists per day visit the city. The attacks tended to affect people who were out doing things that evening (people who stayed at home were safe). Assume all 43,000 tourists were out. What about the general population? Maybe 10% are out in a given evening? Just a guess. So that’s 43,000 + 220,000 = 263,000. The horrific attacks killed 130 people. 130/263,000 = 1 in 2023. Again, this is a “high risk” estimate; I think the actual odds are lower.
Combine the two, you get the risk of dying in an attack, assuming you’re in Paris for four days: 1 in 554,000.
What about London? They had two attacks in the first half of this year; 12 people killed total. The numbers are different – more frequent attacks, but lower casualties; our stay in London was longer. But the math is similar. I won’t bore you with the details, but I came up with: 1 in 759,000.
Compare that to the risk of dying on the drive to and from the airport (SFO) to take the flight: 134 miles round trip, 1.25 deaths per 100 million miles; works out to about 1 in 597,000.
So, I guess the answer is, I’m as worried about dying in a terror attack in Europe as I am about dying on the drive to the airport. Which is, not very much.
