Pick your poison

[phantom power]

There's another kind of happy-sunny killer that he doesn't mention: drought. But anyway, interesting discussion of air pollution.

A huge, destructive hurricane takes aim at a major U.S. city. The media creates a riveting drama, followed by millions of people, who watch in awe as the massive storm smashes ashore. Grimly, wind-blown reporters and concerned news anchors document the mounting death toll and billions in damage wrought, bemoaning nature's deadliest and most destructive weather phenomena--the hurricane.

We've got it all wrong. The hurricane is not nature's deadliest and most destructive weather phenomena. Yes, hurricanes have taken a terrible toll in the U.S. over the past 20 years. They've killed an average of 150 people and caused $15 billion in damage per year--mostly thanks to Katrina. But the nation's deadliest weather events are not destructive storms that shred cities. Nature's most innocent weather--high pressure systems that bring sunny skies and light winds--are our deadliest weather events, thanks to the witch's brew of pollution we pour into our atmosphere.



Figure 1. Pick your poison--a Category 5 hurricane, or a sunny high pressure system with light winds? If you're an asthmatic, or have heart or lung disease, you'd probably be better off picking the Cat 5 hurricane. Photo of Los Angeles smog courtesy of wunderphotographer boytonbeachboy.

How many people does pollution kill?
Why is it that air pollution episodes that kill thousands of Americans don't receive the media attention that hurricanes get? It's because it is not obvious when someone dies from air pollution, and there is very large uncertainty in the numbers. The only way to see air pollution deaths is to analyze death rate statistics for multiple years, carefully filtering out other influences such as weather extremes. Over two thousand studies have been published in the scientific literature documenting the link between air pollution and higher death and hospitalization rates. Most of these studies concern fine particulate matter (less than 2.5 microns in diameter), which can get deep into a person's lungs and be passed into the blood stream. Recent studies have also documented higher death rates from ozone pollution. For example, in a 2004 study published in the Journal of the American Medical Association, Dr. Michelle Bell, an air quality and health expert at Yale University, found that an ozone increase of 10 parts per billion increased the death rate by an average of .52% in 95 U.S. cities (containing 40% of the U.S. population) during the period 1987-2000. Bell's research implies that a change in the ozone standard from the current 80 ppb (parts per billion) to the newly proposed standard of 60 ppb could prevent nearly 8,000 premature deaths per year in those 95 cities. About half of the people who died prematurely in Bell's study were over age 75, but the death rate increased the same amount for both young and old. In some cases, the people who died were victims of strokes or heart attacks that had other contributing causes, such as high blood pressure or sedentary lifestyles. Thus, the "premature deaths" caused by air pollution are only partly attributable to breathing bad air, while drowning in a hurricane's storm surge is entirely due to the hurricane. Nevertheless, a great many children die of pollution-induced asthma attacks who would not have died otherwise, and the mortality due to air pollution in the general population is in the thousands or ten of thousands each year. Outdoor air pollution in the U.S. due to particulate pollution alone was estimated by the EPA in 1997 to cause at least 20,000 premature deaths each year. A 2005 study by EPA scientists (Particulate Matter Health Risk Assessment for Selected Urban Areas) estimated that over 4,700 premature deaths occur each year in just nine cities (Detroit, Los Angeles, Philadelphia, Pittsburgh, St. Louis, Boston, Phoenix, Seattle, and San Jose)--even if those cities all met the current federal standards for particulate matter pollution. Extrapolating these data to the entire nation puts the annual death toll in the tens of thousands--but the EPA has not calculated that total. Some studies have placed the annual pollution death toll in the U.S. at 50,000 to 100,000 (Dockery, D.W., and C.A Pope III. Acute Respiratory Effects of Particulate Air Pollution. Annual Review Public Health, 1994, vol. 15,107-32.) The death toll is much higher in other parts of the world, where air pollution standards are not as stringent (see the photos below of pollution in Cairo and Hong Hong!) Globally, about 800,000 people per year die prematurely due to outdoor air pollution, according to a 2005 study published in the Journal of Toxicology and Environmental Health. This represents about 1.2 percent of total annual global deaths.

http://www.wunderground.com/blog/JeffMasters/comment.html?entrynum=663&tstamp=200705

[NNadir]

1. It is difficult to get a reasonable assessment of this problem.

I've heard a lot of figures for air pollution deaths. The World Health Organization says that there are 1.6 million deaths around the world simply from burning biomass indoors. But I'm not sure how they know that.

[phantom power]

2. The sort of thing you can only tease out with statistics.

So, the quality of our knowledge is only as good as the statistical samples and methodology. A lot of demograhics strikes me as shaky, but it's just a complicated problem. People's lives and deaths are the outcome of many many things. Teasing a reliable signal out of that complexity is tricky.

[phantom power]

3. This reminds me of a story from my father in law.

He is an anesthetist, and told me a story about a runner who came to the hospital complaining of breathing problems. To his astonishment, he was diagnosed with emphysema. Although he never smoked in his life, he did his running for years along a busy highway, breathing in the pollution.