The killer fog: when green politics masquerades as environmental science. (Culture and Reviews).

When Smoke Ran Like Water: Tales of Environmental Deception and the Battle Against Pollution, by Devra Lee Davis, New York: Basic Books, 336 pages, $26

FACTS MUST COME before philosophy. The question of whether air pollution quietly kills millions of people has to be decided by examining the evidence, not by checking that claim against one's political principles, be they environmentalist, pro-market, or something else.

In the first half of When Smoke Ran Like Water, Devra Lee Davis, an epidemiologist and public policy professor at Carnegie Mellon University, goes to great lengths to demonstrate her credibility by examining data, describing clear-cut environmental catastrophes, and giving readers useful lessons in epidemiology along the way. Somewhere around the middle of the book, though, a strange thing happens, and even a sympathetic reader must begin to doubt Davis' scientific objectivity. As is all too often the case with the environmental movement Davis represents, the data quietly fade into the background, their dire implications often taken for granted, while moving anecdotes and denunciations of political foes take center stage.

In the first part of the book, Davis recounts the disaster that befell her childhood home, the small steelmaking town of Donora, Pennsylvania. The town's mills constantly gave off chemical fumes, which most citizens accepted as a necessary byproduct of their livelihoods. In October 1948, a dense blanket of cold air and fog settled over the valley in which Donora was nestled. Fumes from factory smokestacks could not escape, and the haze of pollution became so dense that visibility was limited and doctors advised the infirm to get out of the valley. An unusual number of illnesses occurred among those who remained, and some 18 people died in a 24-hour period.

Davis notes similar tragic incidents in Liege, Belgium, in 1930, where a "killer fog" trapped heavy pollution and killed dozens, and in London in i952, while debate still raged over the exact cause of the events in Donora. Her account is a sobering reminder that air pollution was once the industrialized world's chief environmental problem and that it remains a serious dilemma in the developing world. While today's environmental debates in the developed world typically concern hard-to-detect chemicals and subtle or hypothetical health effects, a century ago in London one could see the pollution, tuck and brown in the air, and feel it in the lungs. Even today, in places such as New Delhi, just stepping outside can induce coughing in newcomers.

Davis carefully explains how epidemiologists go about determining whether pollution during extraordinary incidents such as the killer fogs in Donora and Liege can be fatal. They compare normal death rates for cities of those sizes to the elevated death rates during the fogs. This, she suggests, is the dispassionate, rational business of scientific inquiry in which she and other public health experts are engaged.

From the opening pages, however, Davis plants the seeds of another, more emotive line of argument. She clearly wants the reader to fear that mass death caused by pollution may be going on all around us on a regular basis, not just in the past and not just during periods of exceptionally high pollution--and she wants that fear to haunt us whether or not the hard numbers exist to prove that the fear is warranted.

She describes the tragedy in Donora with understandable passion, and she expresses frustration over the fact that it is so difficult to get a solid count of the victims in such cases, given the stealthy nature of pollution and the subtlety of the statistical evidence. At the same time that she extols the virtues of hard data, she suggests that the above-average rate of heart disease in her own family was caused by the pollution of Donora--something she admits she couldn't even get her own mother to believe: "Uncle Jack, Aunt Ruth, Aunt Gert, and my mom...all developed some form of cardiovascular ailment." This is related with great emotional force, but it is anecdotal reasoning, not epidemiology.

Davis' anecdotes are not confined to Donora. Her Uncle Len died of a heart attack years after leaving Donora, on a smoggy day in Los Angeles in 1969. Did he die because of L.A.'s then-legendary air pollution? We do not know--and neither does Davis, as she briefly acknowledges. Yet all but the most careful readers will be left with the impression that he died from smog and that many others have as well. Davis describes Uncle Len's athleticism at great length, hinting that such a strong man could not simply drop dead of a heart attack. "'Heart attack' is what his death certificate said," she writes. "That is what thousands upon thousands of death certificates said for folks who happened to succumb at times of high pollution."

As if the tragedies of Donora and A Uncle Len were not enough to put us in the right frame of mind, Davis tells us about friends and relatives who survived the Holocaust, noting that the exact numbers of those killed by the Nazis will never be known. Davis claims that she is not suggesting any parallel between those murdered and forgotten during the Holocaust and those whose deaths due to pollution are overlooked today, but she pointedly strikes one of the most powerful emotional chords in the modern psyche. She uses a similar tactic in the Donora narrative, where she expresses frustration over the fact that the "killer smog" victims, upon autopsy, had healthy, clean-looking lungs--and then notes that the same was true of poison gas victims during World War I.

By noting the uncounted dead--and by lamenting that Uncle Len's cause of death cannot be stated with certainty--Davis turns her lack of hard numbers, which by epidemiological standards would be considered a weakness, into a rhetorical asset. Not only is pollution a crime, the reader is led to feel, but it is a crime that dishonors its victims by leaving no clear record of their manner of death. Like extraterrestrial visitors or God, fatal pollution is made to seem all the more ominous and powerful precisely because it is undetected.

Davis' rhetorical flourishes and innuendo would be forgivable if they were merely used to set the stage for hard data about the ongoing toll of air pollution. But when she discusses pollution from around 1970 and since, her narrative undergoes a shift. We hear more tales of struggles between activists and industry than explanations of epidemiological research. There are few of the numbers, graphs, and scientific experiments one might have anticipated from reading her earlier capsule lessons in how to do hard science.

Instead, the floodgates of politics are opened. We are suddenly treated to Davis' stories of working with U.S. Rep. Bella Abzug (D-N.Y.), who was convinced that the high rates of breast cancer on Long Island must have an environmental, probably corporate, cause. A recent National Cancer Institute study concluded that women on Long Island were not exposed to chemicals at an abnormal rate, suggesting that genetic or other demographic factors might explain the very slight elevation in breast cancer rates there. But Davis dismisses this report as "unproductive" and "bogged down" in bureaucracy. Instead of painstakingly explaining where the study went wrong, Davis gives us an extended description of Abzug's own struggle with breast cancer.

We are also told that polychlorinated biphenyls (PCBs), chemicals formerly used in flame retardants and electrical insulation that still linger in the environment, are taking a terrible toll on human health. Davis claims that hermaphroditism in polar bears and alligators shows that PCBs and various man-made "environmental estrogens" account for reduced human sperm counts and may threaten the future of the human race. Even if Davis is right in suspecting that estrogen-mimicking chemicals can affect human hormones, the actual demographic numbers of boy births vs. girl births hardly suggest a crisis: From a 1970 ratio of about 106.5 boys per 100 girls, she tells us, we have plummeted to...105.2 boys per 100 girls. Serious crisis, minor shift, or chance variation? Davis thinks it's the former, but she doesn't make a case for that view.

Throughout her description of this and other pseudo-crises, we are repeatedly asked to see regulators who act before the data are in as courageous figures. In her estimation, they are unwilling to sit idly by while tragedy strikes. Davis praises science one moment and the next moment praises those unwilling to "wait" for science's answers.

In away, this shift in Davis' tone is fitting: It reflects a real change in the environmental movement during the last 30 years. The problem of severe air pollution has been diminishing in the industrialized world, and that change has sent environmentalists in pursuit of more nebulous threats. Groups such as Greenpeace, which once addressed problems visible to the naked eye--smoggy air, garbage-filled rivers-now warn of minuscule or hypothetical risks from industrial chemicals or biotechnology.

Some parts of the developing world, such as Mexico City and China, face increasing levels of pollution, as Davis documents. Air quality has become measurably worse in some places as industrial activity has increased and population has grown denser--but it should not be inferred from this trend that our own pollution problems are getting worse.

Why has air pollution lessened in the developed world? The past few decades have seen a combination of cleaner technologies and regulations that have limited emissions from factories, cars, and other sources. Whether the regulations that helped create those improvements should have been more market-based is open to debate. (Indeed, that debate was reopened in November, when the Bush administration rolled back some parts of the Clean Air Act, allowing companies and local governments greater flexibility in choosing the most efficient means of reaching pollution-reduction goals.) There is little question, though, that when people become wealthy enough to turn their attention to subtle problems like pollution (instead of more immediate ones like starvation), they do so, and the developing world will no doubt follow the same pattern in short order.

Pollution is, among other things, a violation of property rights and bodily integrity; one need not sign on to a radical green agenda to object to it. One ought, however, to avoid extrapolating from the environmental movement's past victories to the conclusion that today's vaguer, more dubious threats are producing a hidden body count as great as the one produced in decades past. Furthermore, one should avoid depicting those who doubt such threats as stubborn, obstructionist tools of industry. But Davis remembers how reluctant Donora's mill owners were to shut down during the "killer fog," and she repeatedly implies that her intellectual opponents in more recent decades are equally obtuse and malevolent.

In the interest of full disclosure, I should note that one writer she attacks (for his criticism of recent air pollution epidemiology) is Joel Schwartz, who has done work for both the Web site I edit, HealthFactsAndFears.com, and the Reason Public Policy Institute, a think tank operated by the foundation that publishes this magazine. Davis says Schwartz and all such critics of environmentalism are playing "public relations games" and "hindering legitimate Science." Again and again, when the work of Davis and her allies is questioned, she simply dismisses her opponents as industry mouthpieces. Any link to industry, no matter how indirect, is sufficient to call into question the objectivity of scientists and commentators who doubt Davis.

Apparently, though, no bias is created by growing up in a town where numerous people reportedly were killed by industrial pollution; believing that several members of your own family have heart disease because of that pollution; grieving for your beloved Uncle Len's death in the L.A. smog; or being on friendly terms with people like the alternative medicine guru Mitchell Gaynor. In the foreword to Davis' book, Gaynor assures readers that her fears about pollution--and his own--are based on "abundant evidence" and "voluminous scientific literature." Perhaps, but it is worth noting that Gaynor also believes in using noise-making "Tibetan singing bowls" to combat cancer.

Davis goes to great lengths to describe her more orthodox views on epidemiological methodology with textbook clarity, but when it comes to more controversial matters--precisely when we most need her to be clear and forceful--she glides quickly over her opponents' objections, pausing only to describe them as flacks for polluting companies. So you will learn nothing here about whether high-dose animal experiments really are good predictors of human health effects, or whether there are minimum doses of pollution (as with most poisons) below which we need not fear health effects. On such questions, Davis in effect asks us to trust her intuitions, intuitions shaped by her own unusual experiences and strongly held beliefs.

Even Davis' concluding anecdote, metaphorical and inconsequential though it is, calls her accuracy into question. After noting that she is now involved in a group that seeks to combine religious life with environmental concerns, Davis tells us that she heard a traditional Midrash fable in childhood, a fable that she now sees as a metaphor for her struggle against pollution.

In the original story, she says, a female rabbi is rescuing starfish on the beach by throwing them back into the water. A little boy tells her that her efforts cannot make a difference because the beach will be covered with starfish again the next day. The rabbi tosses another starfish out to sea and says, "Made a difference to that one."

Cute, noble, defiant. A great little story. But since the first female rabbi in the United States was not ordained until 1972, how plausible is it that a girl growing up in the 19505 would have heard a Midrash story featuring one? I do not ask out of a desire to defend patriarchal religious traditions. I ask because it is one of those nagging little details that leave the reader wondering whether Devra Lee Davis is as sure of her facts as she is of her mission.

Todd Seavey edits HealthFactsAndFears.com, a webzine published by the American Council on Science and Health. He is writing a hook titled Conservatism for Punks.