Americans of a certain age may well remember one of the most frightful images of the 1950s, and no, it's not a mushroom cloud over the Nevada desert. It's the iron lung, a ghastly, cylindrical contraption that pumped air into the paralyzed lungs of the polio victim lying inside.

The iron lung was used in some instances only temporarily, and did save lives. But for some polio victims, many of them children, the iron lung was a coffin in which they lived out their lives, unable to move, forcibly ventilated, 24/7, year after year.

Thankfully, the iron lung has vanished from our collective memory. The dreaded poliovirus that spawned its invention has been vanquished, and there is no parent in this country who fears sending his or her child to the city pool this summer, as parents did prior to the introduction of the polio vaccine in 1954.

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Scientists who study emerging diseases strongly suspect, and have evidence to show, that newly emerging diseases are tied to the ways in which we alter our environment.

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Once a scourge, polio is only a bad memory in the developed world. It's being driven from the developing world as well, one village at a time. In time, polio will go the way of smallpox, another plague banished by science.

It wasn't long ago that infectious disease was considered a career dead end for young scientists. Though polio, smallpox, measles, mumps, rubella, pertussis, cholera, yellow fever, malaria and diphtheria have long ceased to plague American and European cities, infectious diseases are making a comeback.

Newly emerging diseases – HIV, hanta virus and West Nile virus, to name but a few - burst into being only recently, seemingly out of nowhere. While most of us are mystified about the how and why of this new viral explosion, scientists who study emerging diseases strongly suspect, and have evidence to show, that newly emerging diseases are tied to the ways in which we alter our environment.

A few examples:

About three decades ago, researchers interested in stopping the spread of the ubiquitous knapweed began collecting the weed's natural predators from central Europe, where the weed is native. Knapweed is responsible for huge agricultural losses in western Montana, and is turning some sections of the Frank Church River of No Return Wilderness into a weed-choked monoculture.

Ridding western Montana of knapweed was, and still is, considered an impossible task. Halting its spread, however, was thought noble, necessary and most of all, doable, not so much with chemical herbicides, but by releasing gall flies, which feed on knapweed seed heads, thereby limiting the spread. For some years it seemed the experiment was successful; though knapweed has become a permanent fixture on the landscape, it no longer thrives as it did before the release of the predator gall fly.

But last year, one Forest Service scientist discovered something disturbing about gall flies. The insect, gathered from Europe and bred and released across western Montana for thirty years, lays eggs which successfully overwinter in the weed seed heads. The gall fly larvae seems to have become a new and important food source for deer mice, which would normally die off over the winter, leaving only small surviving populations in spring. In test plots, the deer mouse population increased by nearly three times. And with the increase in deer mice populations came a corresponding increase in hanta virus, a deadly respiratory disease carried and transmitted by deer mice and discovered only a decade ago.

In the arid Powder River Basin area of northeast Wyoming, 60 million gallons of water are pumped out of the ground to the surface every day, the result of coalbed methane well drilling. Warm, shallow ponds have formed across the drought-plagued landscape, creating perfect breeding grounds for mosquitoes, particularly Culex tarsalis, a species widely distributed across North America west of the Mississippi.

Last summer, researchers discovered that six of eight radio-collared sage grouse hens at the coalbed methane site near Spotted Horse, Wyo. died of West Nile encephalitis. At two other nearby sites, where there is no coalbed methane development, only one of 42 radio-collared sage grouse hens died of the virus.

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At some point we have to stop being cynical about our government. And in any case, mankind clearly is not going to stop altering his environment.

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More research is necessary before scientists can confirm the link between coal bed methane development and West Nile encephalitis, but it is a fact that Culex tarsalis is a particularly efficient vector of encephalitis.

Chronic wasting disease has been documented in penned game farm animals, and the possibility exists that the disease can be transmitted from penned herds to free-ranging wildlife. The transmission route is unknown, but it appears likely that animals must be in close contact for the disease to spread. Penned elk also have been known to escape into the wild, breeding with red deer and polluting the gene pool. The long-range consequences of interbreeding are unknown, but wildlife biologists fear they could be serious and irreversible.

Rocky Mountain Spotted Fever appeared suddenly on the Montana side of the Bitterroot Range in the late 19th century. The native Salish were unaware of the disease, as were the Jesuit priests who established a mission in the Bitterroot Valley, the epicenter of the pestilence. Capt. William Clark, on his return trip through the Bitterroot Valley in early July 1806, when his men could have been expected to come into contact with ticks, did not report the disease.

What was it that created the conditions necessary for the sudden appearance of tick fever? Scientists believe it was the deforestation of the west side of the Bitterroot Valley. In 1887, one timber mill was cutting 10,000 feet of lumber a day. Less than a decade later, the Bitterroot Range was yielding between 60 and 70 million board feet annually. The scrub vegetation that grew up on the forest in the wake of so much deforestation created habitat for many small mammals that harbored the pathogen and the ticks that fed on the mammals.

If we are to keep free of infectious diseases it seems clear that disease prevention rather than disease cure should be the goal. In fact, preventing disease is the foundation of public health in this country.

At the turn of the 20th century, New York City, the birthplace of public health, was a disease-ridden cesspool. Crowded tenements, dangerous working conditions and lack of plumbing and sewage disposal created the perfect conditions for the spread of contagious diseases. Improvements in housing, occupational safety laws and proper plumbing arguably did more to improve the human condition than did the introduction of antibiotics decades later.

But disease prevention in the 21st century is considerably more complicated than making infrastructure improvements. It would mean that humans would have to stop clearing the forests, cease penning wild game and put an end to burning fossil fuels, which has been linked to about two dozen recently identified infectious diseases. But changing human behaviors and consumption patterns globally is as likely as finding a cure for HIV/AIDS by tomorrow morning.

The only remaining alternative, then, is scientific research that will lead to therapies for diseases that only recently burst on to the world scene: hemorrhagic fevers, tick-borne encephalitis and others designated Biosafety Level 4, because of their deadliness and lack of therapies.

And that means public acceptance of more strict containment research labs.

The National Institutes of Health has made the study of emerging infectious diseases a priority, and has received funding for the construction of four Biosafety Level 4 labs.

In one location, Hamilton, Mont., the NIH has proposed a $66.5 million, 105,000-square-foot Biosafety Level 4 lab within the enclosed perimeter of the 76-year-old Rocky Mountain Laboratories.

The new lab will allow scientists to study the world's most virulent pathogens in a secure environment. But opposition groups in Hamilton - and in Boston, Mass. and Davis, Ca., two other proposed locations for Biosafety Level 4 labs - have formed in a shortsighted effort to stop the projects from moving forward.

Three groups in Hamilton and Missoula forced the government to expand its environmental analysis of the project, but didn't stop the project entirely. In June, the NIH announced that construction of the lab would begin by summer's end.

Opposition to such an intellectually exciting project has been disappointing, shortsighted and selfish. The arguments against the lab run the gamut from mundane concerns over noise and dust during the construction phase to vague worries of accidental release of deadly viruses into the surrounding neighborhood to unfounded fears that the lab will shift its focus from public health research to bioterrorism weapons manufacturing.

Noise and dust problems affect only a small area, and in any case will last only a short while. The pathogens that someday might be studied at the Hamilton lab already exist in many environments around the world, including in western Montana, which has experienced hanta virus. And, finally, the U.S. is prohibited by international treaty from developing bioterrorism weapons.

It's that last statement, of course, that draws the most contempt from opponents who doubt whether the duplicitous Bush administration can be trusted to adhere to the treaty. Said one man: You can just bet that if the government is going to do it, they'll screw it up somehow.

That argument doesn't take into consideration the public health problems created by private companies which, arguably, have made more people sick than any government screw-up – Hooker Chemical at Love Canal, N.Y., Northeastern Pharmaceutical and Chemical Co. at Times Beach, Mo. And, of course, W.R. Grace at Libby, Mont.

At some point we have to stop being cynical about our government. And in any case, mankind clearly is not going to stop altering his environment. There's neither the societal will nor the political leadership to make us consider the consequences of our ecological recklessness.

The next best approach, then, is developing therapies for what ails us.

At its core, the opposition to Biosafety Level 4 labs is selfish because virtually everyone in the developed world has been vaccinated against the diseases that in recent memory killed, scarred, crippled or maimed.

We don't much fear the really scary, science fiction germs such as Ebola because they don't live in our neighborhoods.

But they live in other people's neighborhoods and those people deserve the same world-class science that vanquished our own former public health enemies.

Opponents to the Biosafety Level 4 labs say they fear that a killer virus will somehow escape into the environment. Those viruses are already loose in the environment. The point of these labs is to create a safe place to study them so that someday they'll be banished entirely from the environment. Just like smallpox.