If the tooth fairy gave you 10,000 RMB every year in China that you could only spend on your health, what would you buy? Would you get an air purifier? How about a gym membership; an organic delivery service; a daily massage — what would you choose? Perhaps it’s best to rephrase the question, “what gives my health the most bang for the buck?” In order to answer that, one needs to know which lifestyle choices are harmless fun and which are unhealthy.
Air Pollution : A Lifestyle Choice?
Many in China, both local and foreign, would instinctively say that air pollution is their greatest threat to health, but is it really? Let’s make a slight intellectual leap and say that exposure to air pollution is a lifestyle choice; in other words, a modifiable risk factor. I know that breathing is of course involuntary, but most of my readers do have a choice whether or not to live here in China. If you accept this admittedly disturbing assumption, you can then compare this always dreaded “risk factor” to much more mundane risks we all encounter — such as obesity, smoking, lack of exercise, poor diet and other lifestyle choices.
We can clarify lifestyle choices even further into what the American Heart Association calls the four ideal health behaviors:
- not smoking
- not being overweight (body-mass index (BMI) <25 kg/m 2)
- physical activity at goal levels (>150 minutes a week of moderate exercise)
- diet that includes three or more servings of fruits and vegetables daily.
The AHA also lists three ideal health factors, including total cholesterol <200 mg/dL, systolic blood pressure <120 mm Hg and diastolic blood pressure <80 mm Hg, and fasting plasma glucose levels <100 mg/dL.
How many of these seven metrics do you pass? Don’t feel too guilty, as only 1 percent of the AHA’s test group of 7,622 persons passed all seven. But here’s the clincher: compared with individuals who didn’t meet any of these seven measures, those with five or more had a 78% lower risk of all-cause mortality and an 88% lower risk of death from diseases of the circulatory system. That’s impressive, no? But it’s much more interesting to find out exactly which of these ideal goals is most efficiently beneficial. Plus, how do they compare to air pollution?
It’s All About The Relative Risks
I’m a data junkie, and I find hard numbers very comforting in the midst of my hectic “medicine is art” family medicine clinic. My favorite tool to compare health outcomes is the relative risk; this compares the ratio of a disease’s prevalence from a health exposure as compared to non-exposure. It’s simple division: divide numerator (exposure) by denominator (no exposure) and you have your ratio, your “RR”. Any RR over 1 signifies a positive risk, and under 1 is a “negative” risk, i.e. a benefit. Let’s use air pollution and smoking as initial examples. As I mentioned in my controversial post earlier this year, a day in Beijing is comparable to smoking 1/6 of a cigarette, which for many of my readers was scandalously low, almost heretical to their predisposed belief systems. Sorry, true believers, but you can crunch the numbers yourself from Dr C Arden Pope’s sudy. From this study, we can calculate relative risks of lung cancer for air pollution, smoking and secondhand smoke:
- Air pollution (from American Cancer Society and Harvard Six Cities studies): 1.14-1.21 relative risk
- Air pollution in Beijing: 1.49 RR
- Secondhand smoke victims: 1.21-1.28 RR
- Smoking 3 cigarettes a day: 5.6 RR
- Smoking half a pack a day: 7.7 RR
- Smoking a pack a day: 12.2 RR
- Smoking two packs a day: 19.8 RR
As the numbers show, “light” smoking of only 3 a day is far more deadly than living with Beijing’s air pollution. Since writing that article last winter, I’ve achieved a certain catharsis on this issue, and my personal obsession with air pollution has mellowed from debilitating to professionally curious. I’m now more concerned with the much less glamorous lifestyle choices that bedevil all developing societies, all eagerly latching onto the “Western” lifestyle and quickly picking up both the best and the worst of such lifestyle.
I’m particularly worried about obesity, the great pandemic of our times and an astonishingly pervasive crisis in my homeland, the USA. When I make my annual visit home on Boston’s south shore, I’m truly shocked just how large are the average American adult and child. Having spent six years outside of America, I can peer back with increasing impassivity and state that Americans simply don’t realize the true state of this public health disaster. One of my all-time favorite public health graphs, taken from data from a 1999 NEJM review article, shows the relative risks of increasing weight on coronary heart disease, diabetes, high blood pressure and kidney stones.