In the realm of fuzzy math and statistical manipulation, nothing sounds so wonderful as things that'll add years to your life and nothing so scary as things that'll take those years away. And though we're not scientists or number-crunching pros, we don't want to feel like suckers when it comes to fear mongering figures.
So let's take a look at London's newest set of mortality figures, which supposedly triumph the roughly quarter decrease in traffic due to the congestion charges on the city center. See if you can wrap your head around this fact BBC News reports from a study in Occupational and Environmental Medicine:
Scientists from two London colleges calculated that since 2003, 1,888 extra years of life had been saved among the city's seven million residents.
OK, scientists, we're with you! We want to add years to our lives! We love our lungs! We know pollution is bad for us, and cars cause lots of pollution. Congestion charges are saving our lives!
But wait, what do the numbers really mean? Lets take a look at the figures, further analyzed by more scientists, to understand where these numbers are coming from.
Within the central charging area itself — where relatively few people actually live — the benefits seemed more significant, with an extra 183 years of life saved for every 100,000 residents.
So let's do the math on the best-affected area: 183 years divided by 100,000 people is an awfully small number. Further divided by the four-year time range? Miniscule. Multiplied by 365 days? Still just a fraction. Multiplied by 24 hours? Now we're getting somewhere: The scientists are talking about 4 hours of life per person.
Looking at the figures per person, however, isn't even accurate. Those saved years go disproportionately to sustain those with existing heart and lung problems by helping them breathe in more oxygen and fewer nasty tarry particles. Sure, we're happy that Grandma will have a better time breathing, but touting this small change as a real health benefit for the whole population? That might be going too far.
And what about the bulk of Londoners, who don't live in the congestion zones and are subjected to vehicles free to run rampant with their particulate emissions? The unnamed scientists found that outside of the city center, the reduction in pollution resulted in 18 years of life per 100,000 residents, or about 24 minutes per person.
And that original, impressive-sounding number — 1,888 extra years of life for Londoners — if really divided among the population, amounts to about 35 minutes of life per person.
We're not saying we want more pollution or think 35 minutes of life aren't valuable. We just don't know if it's a significant enough increase to warrant patting the congestion charge on the back.
Congestion charge photo courtesy of otzberg's Flickrstream