Greetings, Takers of the A-train,
Last night I went to a show in the big city. As you know, I don't own a car, so I took a subway car back, and noticed how very odd it was that about 100 rich patrons waited with me for over 20 minutes for a train. (My metropolitan area has notoriously infrequent trains, especially at night.) It got me wondering: how crazy is it (financially) to run trains infrequently at night?
Extra Costs
It's easy to say "Let's just run trains every minute," but the whole reason why public transit systems work is that many people going the same way can use just one vehicle and driver. Let's figure out the cost of splitting one infrequent but long subway trains into two shorter trains.
If the run lasts two hours and the driver costs $40/hour (including overhead, training, etc.) the personnel expense is $80. The necessary force (hence electricity cost) of pushing an additional train front through the air can be calculated using:
F = .5 A D p v^2,
where A is the area of the train front, D is a drag coefficient (usually about .25 for aerodynamic shapes), p is the density of the medium and v is the speed. Using A D = 4 m^2, p = 2kg/m^3, v = 20 m/s, electricity costs $.15/kWh and the distance traveled is 100 km, we see the extra energy costs is a measly $7. Let's round up and say an extra $100 would be needed to run an extra train.
Extra Benefits
So, how much shorter a commute would there be if an extra train came? The trains come every 24 minutes, and by the time a train came last night there were over 100 people waiting at my station and over 100 at the next station (the two busiest, mind you); let's lowball the estimate and say 250 people would be able to catch a train on average 6 minutes sooner if train frequency were doubled. Doubling train frequency means 25 commuter hours would have been saved at a cost of $100 to the system: $.40 per passenger or $4/hour of passenger time saved.
However, increasing service might increase ridership, so it's possible that the extra train would (at least partially) pay for itself. Increasing ridership eases burdens on parking and roads too; public transit is overall a good bargain.
Summary
It's time commuters got vocal about being willing to pay a fair amount for their time that gets wasted by sluggish schedules. I wish we'd get a consistent metric of how much our time is worth, and use it to make policy decisions. Check out my post on machine wages for equivalent cost-time comparisons; this concept may evolve into a wiki page soon.
Keep on track!
LeDopore
Showing posts with label motor vehicles. Show all posts
Showing posts with label motor vehicles. Show all posts
Thursday, September 20, 2007
Thursday, September 13, 2007
Life in the Slow Lane
Greetings, road warriors.
This post is about commuting; specifically why I refuse to do long commutes. I don't really understand why people put up with long commuting. Some of my coworkers get up at 4 AM to get to work on time (8 AM), twice a day wasting in traffic more time than it takes to travel by train from Rome to Naples. Where do I start with the problems here? That kind of squandering of human life is so egregious that I don't even know where to start to try to attack it: res ipsa loquitor! If that res still isn't very loquacious, read on!
In an earlier post, I quantified how much you pay labor-saving machines for each hour of chores they save you; here I'm going to figure out how much you're paying yourself to live in a cheap neighborhood and commute to a good job.
Tinned Nation
On average last year, Americans spent 50 minutes per work day commuting to and from their jobs; mostly in a sitting position within oversized metallic cans on wheels. However, like the aforementioned coworkers, over 3.4 million Americans spent more than three hours per day commuting to work. If these extreme commuters value their time at $25/hour and work 20 days per month, they're spending $1500 of their time every month for the privilege of living where it's cheap. Unless housing is drastically more expensive where they work, it's just not worth their time.
Leisure sucker
Commuting is more than just a monetary problem, however: the less free time you have the more precious it becomes. If you're awake 16 hours a day, work 8 hours and spend 2 hours keeping the household together that leaves just 6 hours of discretionary free time per day. If three hours is sucked up in commuting, you have half the time to pursue self-development.
Greeks to the Rescue?
Aristotle thought the best division of waking hours was to spend 6 hours working, 6 hours resting and 6 hours pursuing some leisured activity: being creative and exercising parts of your body and intellect for the shear joy of it. The 8-hour work day already overbalances this ancient ideal; why tip it further into job-is-everything territory?
Personally I'm dismayed with the fact that the remainder of peoples' time usually has to go towards wakeful resting (like watching the tube), and not the active creation of interesting life, tradition and culture. I want life to be more participatory: we should be having a good time with the freeboard that going to work gives, if the work itself isn't fun (a harsh reality I'm trying to avoid).
Staying Un-Canned
What are some ways to keep our commuting hours down? How about the following for a start;
leave comments if you have more ideas.
Take care, and stay out those cars as much as possible!
LeDopore
Hold infinity in the palm of your hand-- William Blake, Auguries of Innocence
And eternity in an hour.
This post is about commuting; specifically why I refuse to do long commutes. I don't really understand why people put up with long commuting. Some of my coworkers get up at 4 AM to get to work on time (8 AM), twice a day wasting in traffic more time than it takes to travel by train from Rome to Naples. Where do I start with the problems here? That kind of squandering of human life is so egregious that I don't even know where to start to try to attack it: res ipsa loquitor! If that res still isn't very loquacious, read on!
In an earlier post, I quantified how much you pay labor-saving machines for each hour of chores they save you; here I'm going to figure out how much you're paying yourself to live in a cheap neighborhood and commute to a good job.
Tinned Nation
On average last year, Americans spent 50 minutes per work day commuting to and from their jobs; mostly in a sitting position within oversized metallic cans on wheels. However, like the aforementioned coworkers, over 3.4 million Americans spent more than three hours per day commuting to work. If these extreme commuters value their time at $25/hour and work 20 days per month, they're spending $1500 of their time every month for the privilege of living where it's cheap. Unless housing is drastically more expensive where they work, it's just not worth their time.
Leisure sucker
Commuting is more than just a monetary problem, however: the less free time you have the more precious it becomes. If you're awake 16 hours a day, work 8 hours and spend 2 hours keeping the household together that leaves just 6 hours of discretionary free time per day. If three hours is sucked up in commuting, you have half the time to pursue self-development.
Greeks to the Rescue?
Aristotle thought the best division of waking hours was to spend 6 hours working, 6 hours resting and 6 hours pursuing some leisured activity: being creative and exercising parts of your body and intellect for the shear joy of it. The 8-hour work day already overbalances this ancient ideal; why tip it further into job-is-everything territory?
Personally I'm dismayed with the fact that the remainder of peoples' time usually has to go towards wakeful resting (like watching the tube), and not the active creation of interesting life, tradition and culture. I want life to be more participatory: we should be having a good time with the freeboard that going to work gives, if the work itself isn't fun (a harsh reality I'm trying to avoid).
Staying Un-Canned
What are some ways to keep our commuting hours down? How about the following for a start;
leave comments if you have more ideas.
- Arrange to spend one day a week telecommuting (if possible)
- Use a home office
- Rent an apartment close to your job (and price out the time cost of your commute if you live far from your job - you might consider moving then)
- Live/work arrangements are also great
Take care, and stay out those cars as much as possible!
LeDopore
Monday, April 9, 2007
Where Would Gaia Tan?
Greetings, sun-worshipers.
Today's post in by request. A bronzed goddess I know who's recently traveled aboard a Caribbean cruise wanted to know if cruising takes more or less fuel than a transatlantic airplane trip to Europe. Here's my take.
Fuel Cost of Flying
According to this chart from Nova, a typical transatlantic flight aboard a 747-100 will consume 57.7 gallons of fuel per passenger, or 115.4 gallons round-trip. (I'm not sure why they include three significant figures; I'm sure the variation is at least a few percent.) Incidentally, if you could drive solo all the way to Europe you would burn about five times as much, so flying isn't that bad in terms of mileage relative to driving a car alone.
Fuel Cost of Cruising
On the other hand, taking a one-week Caribbean cruise will burn about 140 gallons of fuel per passenger. (Here I assumed fuel efficiency of about 20 feet per gallon on a modern cruise ship - inspired by the QE II's mileage of 29 feet per gallon; a cruising speed of 22 knots, 3500 passengers and 3 days of full-speed cruising of the 7 total days.) The per-capita mileage of a cruise is then about 13 miles per gallon: about the same as driving alone; perhaps a little worse.
Conclusion
A transatlantic flight and a one-week cruise consume about the same amount of fuel. You're not exactly doing Gaia a great favor by vacationing on either, but the occasional vacation isn't going to outweigh habitual energy usage either. If you have a 2-hour commute in your own car, you'd burn roughly 25 gallons per week, so cruising once a year isn't going to overwhelm your daily habits.
Who knows; maybe the next generation of cruisers will like fuel-saving tech like this too? (Personally I would love a nuclear cruise ship as much for its silence as for its eco-friendliness, but I don't think that's in the cards.)
Today's post in by request. A bronzed goddess I know who's recently traveled aboard a Caribbean cruise wanted to know if cruising takes more or less fuel than a transatlantic airplane trip to Europe. Here's my take.
Fuel Cost of Flying
According to this chart from Nova, a typical transatlantic flight aboard a 747-100 will consume 57.7 gallons of fuel per passenger, or 115.4 gallons round-trip. (I'm not sure why they include three significant figures; I'm sure the variation is at least a few percent.) Incidentally, if you could drive solo all the way to Europe you would burn about five times as much, so flying isn't that bad in terms of mileage relative to driving a car alone.
Fuel Cost of Cruising
On the other hand, taking a one-week Caribbean cruise will burn about 140 gallons of fuel per passenger. (Here I assumed fuel efficiency of about 20 feet per gallon on a modern cruise ship - inspired by the QE II's mileage of 29 feet per gallon; a cruising speed of 22 knots, 3500 passengers and 3 days of full-speed cruising of the 7 total days.) The per-capita mileage of a cruise is then about 13 miles per gallon: about the same as driving alone; perhaps a little worse.
Conclusion
A transatlantic flight and a one-week cruise consume about the same amount of fuel. You're not exactly doing Gaia a great favor by vacationing on either, but the occasional vacation isn't going to outweigh habitual energy usage either. If you have a 2-hour commute in your own car, you'd burn roughly 25 gallons per week, so cruising once a year isn't going to overwhelm your daily habits.
Who knows; maybe the next generation of cruisers will like fuel-saving tech like this too? (Personally I would love a nuclear cruise ship as much for its silence as for its eco-friendliness, but I don't think that's in the cards.)
Wednesday, March 7, 2007
Consuming to Curb Consumption: the Case for a new Prius
Greetings, fellow humans.
Today's post is by request. One of my readers who is interested in minimizing his environmental impact asked about whether the energy costs of manufacturing a new car outweigh the energy costs of running an older, less fuel-efficient vehicle. The reader in question bikes to his law firm in all weather but snow, so he's already taken the cheapest (and probably most significant) step towards reducing his transportation-related energy consumption. However, many of us need cars at least once in a while, so it will be fun figuring out how many miles of driving you'd have to do to make buying a new car worthwhile.
Manufacturing a New Car
The Internet's too powerful these days. I thought I'd have to sift through details about modern steel-making techniques to get an estimate of how much energy goes into making a new car. It turns out that Google Answers beat me to it though: the average energy consumption associated with making a new car is 73 Gigajoules. Given that a liter of gas has about 32 Megajoules of energy, that means the energy content of manufacturing a new car is equal to the energy content of about 610 US gallons of gas. Since fossil-fuel-burning power plants are only about 40% efficient, the energy cost of making a new car is equivalent to that of burning about 1500 gallons of gas. (Aside: making cars from recycled steel reduces this energy cost by about 20%.)
Comparing Manufacturing Energy to Use Energy
Now that we know how much energy it takes to make a car, let's see how much you would have to drive a new, fuel-efficient car to make up for the extra energy used in producing it. Suppose that your new car gets about 45 miles per gallon while the old one got only 30. Then, for every 90 miles you travel, you'd save one gallon of gas from the fact that you bought a new car. Since making the new car consumed the equivalent of 1500 gallons of gas, you'd have to drive 135 000 miles to get to the break-even point, energy-wise.
Adding Emissions to the Mix
One thing I haven't factored into my account is the fact that power plants tend to have lower emissions than vehicles, since some power plants are zero-emission and others may have scrubbers (i.e., they may clean their exhaust of the worst polluting chemicals before dumping it into the air). In summary, this report says that 68% of the CO2 emissions from the life cycle of a typical car come from fuel consumption, 21% come from fuel processing and only 11% come from vehicle manufacturing, based on a vehicle lifetime of 120 000 miles. That means that, from an emissions standpoint, you have to drive your new hybrid only about 15 000 miles to reduce your net CO2 output.
Conclusions
I guessed that the energy cost of operating an old vehicle would be much greater than the cost of making a new, fuel-efficient one. The marketing behind new, hybrid cars is slick: it had me thinking about ditching old clunkers in the name of environmental responsibility. It's almost as if there's no corporate muscle behind the message "don't buy a new car while your old one still works." I guess that commercial culture will never miss a chance to tell us to buy something new, even when hiding behind the message "consume less!"
It's true that many new cars will probably make it beyond the 135 000 mile mark, meaning that you could ditch your old car for a new hybrid and rest assured that probably your net energy usage would go down eventually. It's also true that if you're worried about emissions as well as consumption, you would have to drive only about 15 000 miles to break even. Still, the environmental impact of buying additional vehicles, even if they're hybrids, is not insignificant, and should be factored into any decision over "going green" by ditching an old but still usable car.
Today's post is by request. One of my readers who is interested in minimizing his environmental impact asked about whether the energy costs of manufacturing a new car outweigh the energy costs of running an older, less fuel-efficient vehicle. The reader in question bikes to his law firm in all weather but snow, so he's already taken the cheapest (and probably most significant) step towards reducing his transportation-related energy consumption. However, many of us need cars at least once in a while, so it will be fun figuring out how many miles of driving you'd have to do to make buying a new car worthwhile.
Manufacturing a New Car
The Internet's too powerful these days. I thought I'd have to sift through details about modern steel-making techniques to get an estimate of how much energy goes into making a new car. It turns out that Google Answers beat me to it though: the average energy consumption associated with making a new car is 73 Gigajoules. Given that a liter of gas has about 32 Megajoules of energy, that means the energy content of manufacturing a new car is equal to the energy content of about 610 US gallons of gas. Since fossil-fuel-burning power plants are only about 40% efficient, the energy cost of making a new car is equivalent to that of burning about 1500 gallons of gas. (Aside: making cars from recycled steel reduces this energy cost by about 20%.)
Comparing Manufacturing Energy to Use Energy
Now that we know how much energy it takes to make a car, let's see how much you would have to drive a new, fuel-efficient car to make up for the extra energy used in producing it. Suppose that your new car gets about 45 miles per gallon while the old one got only 30. Then, for every 90 miles you travel, you'd save one gallon of gas from the fact that you bought a new car. Since making the new car consumed the equivalent of 1500 gallons of gas, you'd have to drive 135 000 miles to get to the break-even point, energy-wise.
Adding Emissions to the Mix
One thing I haven't factored into my account is the fact that power plants tend to have lower emissions than vehicles, since some power plants are zero-emission and others may have scrubbers (i.e., they may clean their exhaust of the worst polluting chemicals before dumping it into the air). In summary, this report says that 68% of the CO2 emissions from the life cycle of a typical car come from fuel consumption, 21% come from fuel processing and only 11% come from vehicle manufacturing, based on a vehicle lifetime of 120 000 miles. That means that, from an emissions standpoint, you have to drive your new hybrid only about 15 000 miles to reduce your net CO2 output.
Conclusions
I guessed that the energy cost of operating an old vehicle would be much greater than the cost of making a new, fuel-efficient one. The marketing behind new, hybrid cars is slick: it had me thinking about ditching old clunkers in the name of environmental responsibility. It's almost as if there's no corporate muscle behind the message "don't buy a new car while your old one still works." I guess that commercial culture will never miss a chance to tell us to buy something new, even when hiding behind the message "consume less!"
It's true that many new cars will probably make it beyond the 135 000 mile mark, meaning that you could ditch your old car for a new hybrid and rest assured that probably your net energy usage would go down eventually. It's also true that if you're worried about emissions as well as consumption, you would have to drive only about 15 000 miles to break even. Still, the environmental impact of buying additional vehicles, even if they're hybrids, is not insignificant, and should be factored into any decision over "going green" by ditching an old but still usable car.
Friday, February 9, 2007
Fill 'er Up with Air: the 25¢/Gallon Asthma Tax
Greetings, fellow nerds.
Today I'm going to quantify the asthma cost of burning one gallon of gas in the US. Car-derived air pollution is a major contributor to asthma in the United States. Human suffering aside, let's estimate the cost of providing asthma care associated with burning 1 gallon of gas, and figure out who should bear that cost.
Economic Burden of Asthma
A 2003 study estimates the per-capita cost of asthma to be $4,912, and in 2004 there were 17,624,930 Americans with asthma. The total cost of asthma to the US is therefore about $87 billion, although it's likely to have increased since 2004. To put that in perspective, the US trade deficit for 2004 was $611 billion, less than 7 times the cost of asthma.
In 2004, the US burned 20 million barrels of oil per day, which works out to 318 billion gallons for the year. If we were to attribute all the asthma in 2004 to vehicle-caused air pollution, the asthma cost per gallon of gas burned would be just over 27¢. The 2007 costs of asthma must be greater than 2004's 27¢ per gallon, but on the other hand not 100% of asthma is caused by air pollution. (However, asthma rates have quadrupled in the last few decades according to the WHO, suggesting that human-made factors like air pollution play an overwhelming, if not exclusive, role.) In any case, for every gallon of gas you burn, you do approximately a quarter's worth of damage through asthma.
Benefits of the Asthma Tax
Let's add an asthma tax to gas and make it pay for everyone's asthma treatment. It wouldn't be prohibitively expensive; I bet the per-capita cost of asthma would also go down if treatment were universally free, since the cost of treating acute attacks of people who rush into emergency rooms must be a lot higher than the cost of preventative care. This cost-reduction from efficient treatment would mean the average American would pay less total in health insurance premiums and gas combined. Those without insurance would also suffer less, let's not forget. It would be only those whose lifestyle currently creates disproportionally-large asthma suffering who would suffer under the asthma tax.
The Asthma Tax and 21st Century Capitalism
As long as the asthma tax were related to the true cost of asthma care, auto manufacturers would have a financial incentive to keeping the skies clean: they believe they can sell more cars with the price of gas low, and a low incidence of asthma would lower the at-the-pump price. The public and private incentives would be aligned, which is what 21st century capitalism is all about: getting people working together.
Let's not forget the human element of 21st century capitalism. A disproportionate number of poor urbanites suffer from asthma. Imagine the effect of the goodwill they would feel if the rich showed a little compassion by at least paying for the medical treatment of the damage they've done with their smog. If you actively oppose a measure which lowers costs and brings goodwill to humanity, you're a troll.
Conclusion: Let's Do It
In conclusion, the quarter-a-gallon gas tax would relieve human suffering, decrease the financial burden of treating asthma, and provide a direct incentive to auto manufacturers to start taking better care of us. It's a win-win situation; let's get started.
Today I'm going to quantify the asthma cost of burning one gallon of gas in the US. Car-derived air pollution is a major contributor to asthma in the United States. Human suffering aside, let's estimate the cost of providing asthma care associated with burning 1 gallon of gas, and figure out who should bear that cost.
Economic Burden of Asthma
A 2003 study estimates the per-capita cost of asthma to be $4,912, and in 2004 there were 17,624,930 Americans with asthma. The total cost of asthma to the US is therefore about $87 billion, although it's likely to have increased since 2004. To put that in perspective, the US trade deficit for 2004 was $611 billion, less than 7 times the cost of asthma.
In 2004, the US burned 20 million barrels of oil per day, which works out to 318 billion gallons for the year. If we were to attribute all the asthma in 2004 to vehicle-caused air pollution, the asthma cost per gallon of gas burned would be just over 27¢. The 2007 costs of asthma must be greater than 2004's 27¢ per gallon, but on the other hand not 100% of asthma is caused by air pollution. (However, asthma rates have quadrupled in the last few decades according to the WHO, suggesting that human-made factors like air pollution play an overwhelming, if not exclusive, role.) In any case, for every gallon of gas you burn, you do approximately a quarter's worth of damage through asthma.
Benefits of the Asthma Tax
Let's add an asthma tax to gas and make it pay for everyone's asthma treatment. It wouldn't be prohibitively expensive; I bet the per-capita cost of asthma would also go down if treatment were universally free, since the cost of treating acute attacks of people who rush into emergency rooms must be a lot higher than the cost of preventative care. This cost-reduction from efficient treatment would mean the average American would pay less total in health insurance premiums and gas combined. Those without insurance would also suffer less, let's not forget. It would be only those whose lifestyle currently creates disproportionally-large asthma suffering who would suffer under the asthma tax.
The Asthma Tax and 21st Century Capitalism
As long as the asthma tax were related to the true cost of asthma care, auto manufacturers would have a financial incentive to keeping the skies clean: they believe they can sell more cars with the price of gas low, and a low incidence of asthma would lower the at-the-pump price. The public and private incentives would be aligned, which is what 21st century capitalism is all about: getting people working together.
Let's not forget the human element of 21st century capitalism. A disproportionate number of poor urbanites suffer from asthma. Imagine the effect of the goodwill they would feel if the rich showed a little compassion by at least paying for the medical treatment of the damage they've done with their smog. If you actively oppose a measure which lowers costs and brings goodwill to humanity, you're a troll.
Conclusion: Let's Do It
In conclusion, the quarter-a-gallon gas tax would relieve human suffering, decrease the financial burden of treating asthma, and provide a direct incentive to auto manufacturers to start taking better care of us. It's a win-win situation; let's get started.
Thursday, February 8, 2007
Mad about BSE
Greetings, fellow nerds.
This will be just a quick post about the relative risks between the "mad" and the "cow" in mad cow disease. In truth, the danger "tainted beef" poses to us is so small that as a consumer, you should forget about mad cow disease entirely: it's a waste of neurons. I'd even feel guilty making you read this post if it weren't for the fact that it exposes the sensationalism behind mad cow disease reporting.
Assessing Mad Cow Lethality
Mad cow disease in cows is called bovine spongiform encephalopathy (BSE), and to date there have been at least 188515 reported cases of it worldwide. Common sense suggests that there are a whole lot of unreported cases too, considering the incentives farmers have to keep things quiet. The disease humans contract by eating infected cows is called variant Creutzfeldt-Jakob disease (vCJD), and there have been a total of 170 confirmed cases worldwide. This number is probably not exaggerated (in fact the false positive rate for vCJD might be rather high), so you might think of 170/188515 (or about 900 per million) as an upper bound on the chances of contracting vCJD from eating an entire mad cow. However, probably not all of the 188515 cows were consumed in their entirety, which means that 900 per million might be a good ballpark figure as to the actual transmission rate from eating a whole cow.
If there are roughly 250 lbs of meat per cow, and if a typical beef meal has a quarter pound of meat, the odds of catching vCJD from a single meal of infected beef are 900 in a billion. When you consider that in the time period the 188515 cows were detected, the UK (the country hardest-hit by BSE) produced about 100 million cows, the risk of getting vCJD from eating one randomly-chosen UK beef meal is about 2 in a billion.
No Consensus among Academics
Why aren't I just reporting what the medical journals say about BSE to vCJD transmission rates? Because these estimates are all over the place. This study in the journal "Risk Analysis" by Eric Grist shows that there's nothing like consensus regarding the risk of a human contracting vCJD from eating an infected meal: published transmission rates vary from 0.9 in a billion to 7 in a thousand (c.f. my estimate of 900 per billion based on case numbers). The "Risk Analysis" article continues on to point out that the 7 in a thousand measure is obviously inconsistent with observed vCJD infection rates. (Thank you, Dr. Grist!) Perhaps even researchers are prone to sensationalism, especially if the said sensationalism might result in extra funding.
New Risk Metrics
We need better units for analyzing risks. It's hard to grok these raw numbers without an everyday context, so I'm going to introduce two new metrics:
Driving cars is a risky activity that most of us have come to terms with. Driving therefore provides an ideal reality check that helps us put new risks in perspective. This DOT report (page 8 of the .pdf) shows that there are about 14.6 vehicular fatalities for every billion miles traveled. The EDD of a new risk is the length of the car trip with the equivalent level of risk. For example, the EDD of the untested UK beef meal is (2 per billion * 1 billion miles / 14.6) = 720 feet; less than one Manhattan city block. Again, if the beef was in a fast food meal, the EDD from the extra calories is over 6400 miles: greater than the radius of the Earth.
Conclusion: Calories Matter More than Prions
If you spent more than 5 seconds worrying about contracting vCJD from beef, even at the height of the mad cow scare in the UK, you've been had. Also, if you think a fast food meal saves time, you should consider the 2.7-day lifespan decrease it brings (unless you're underweight - see my blog entry). It's true that the risk was unknown at the time (so maybe caution was indicated), but I'm getting sick of people worrying about false alarms, especially when there are more pressing issues which aren't getting enough attention.
I'm also disillusioned with the media, although I can see their point. Nobody will buy a paper saying "Get Off Your Butt and Get Healthy," but "New Plague Risk Sweeps the Nation: Will YOU Die?" has more zing.
As new crises come up in the news, I'm going to try to keep up with the LED and EDD metrics for them. With any luck, they'll catch on as popular reality checks for how risky a new terror actually is.
This will be just a quick post about the relative risks between the "mad" and the "cow" in mad cow disease. In truth, the danger "tainted beef" poses to us is so small that as a consumer, you should forget about mad cow disease entirely: it's a waste of neurons. I'd even feel guilty making you read this post if it weren't for the fact that it exposes the sensationalism behind mad cow disease reporting.
Assessing Mad Cow Lethality
Mad cow disease in cows is called bovine spongiform encephalopathy (BSE), and to date there have been at least 188515 reported cases of it worldwide. Common sense suggests that there are a whole lot of unreported cases too, considering the incentives farmers have to keep things quiet. The disease humans contract by eating infected cows is called variant Creutzfeldt-Jakob disease (vCJD), and there have been a total of 170 confirmed cases worldwide. This number is probably not exaggerated (in fact the false positive rate for vCJD might be rather high), so you might think of 170/188515 (or about 900 per million) as an upper bound on the chances of contracting vCJD from eating an entire mad cow. However, probably not all of the 188515 cows were consumed in their entirety, which means that 900 per million might be a good ballpark figure as to the actual transmission rate from eating a whole cow.
If there are roughly 250 lbs of meat per cow, and if a typical beef meal has a quarter pound of meat, the odds of catching vCJD from a single meal of infected beef are 900 in a billion. When you consider that in the time period the 188515 cows were detected, the UK (the country hardest-hit by BSE) produced about 100 million cows, the risk of getting vCJD from eating one randomly-chosen UK beef meal is about 2 in a billion.
No Consensus among Academics
Why aren't I just reporting what the medical journals say about BSE to vCJD transmission rates? Because these estimates are all over the place. This study in the journal "Risk Analysis" by Eric Grist shows that there's nothing like consensus regarding the risk of a human contracting vCJD from eating an infected meal: published transmission rates vary from 0.9 in a billion to 7 in a thousand (c.f. my estimate of 900 per billion based on case numbers). The "Risk Analysis" article continues on to point out that the 7 in a thousand measure is obviously inconsistent with observed vCJD infection rates. (Thank you, Dr. Grist!) Perhaps even researchers are prone to sensationalism, especially if the said sensationalism might result in extra funding.
New Risk Metrics
We need better units for analyzing risks. It's hard to grok these raw numbers without an everyday context, so I'm going to introduce two new metrics:
- Life Expectancy Decrease (LED)
- Equivalent Driving Distance (EDD)
Driving cars is a risky activity that most of us have come to terms with. Driving therefore provides an ideal reality check that helps us put new risks in perspective. This DOT report (page 8 of the .pdf) shows that there are about 14.6 vehicular fatalities for every billion miles traveled. The EDD of a new risk is the length of the car trip with the equivalent level of risk. For example, the EDD of the untested UK beef meal is (2 per billion * 1 billion miles / 14.6) = 720 feet; less than one Manhattan city block. Again, if the beef was in a fast food meal, the EDD from the extra calories is over 6400 miles: greater than the radius of the Earth.
Conclusion: Calories Matter More than Prions
If you spent more than 5 seconds worrying about contracting vCJD from beef, even at the height of the mad cow scare in the UK, you've been had. Also, if you think a fast food meal saves time, you should consider the 2.7-day lifespan decrease it brings (unless you're underweight - see my blog entry). It's true that the risk was unknown at the time (so maybe caution was indicated), but I'm getting sick of people worrying about false alarms, especially when there are more pressing issues which aren't getting enough attention.
I'm also disillusioned with the media, although I can see their point. Nobody will buy a paper saying "Get Off Your Butt and Get Healthy," but "New Plague Risk Sweeps the Nation: Will YOU Die?" has more zing.
As new crises come up in the news, I'm going to try to keep up with the LED and EDD metrics for them. With any luck, they'll catch on as popular reality checks for how risky a new terror actually is.
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