My opposition to the Holcim Company’s proposal to burn more than one million tires every year at a cement plant at the headwaters of the Missouri River started as a no-brainer.

I have three children growing up downwind of that plant. I float those rivers. Several friends work with the advocacy group, Montanans Against Toxic Burning. I went to meetings, read literature, was persuaded by arguments exposing shaky economics, health risks, degradation of local environment and questionable science.

I attended a public meeting in a Manhattan, Mont., school, where more than 75 people spoke against the tire-burning proposal. Only four or five, all with ties to the cement plant, spoke in favor.

A petition signed by nearly 100 area physicians circulated. The Bozeman City Commission sent a letter urging the state’s Department of Environmental Quality (DEQ) to pursue a complete environmental impact statement; finally, the state agreed. Case closed.

Or was it? I began making calls, reading documents, asking pointed questions, and that's when things started to get muddy. Not just dense and complicated, as you'd expect, but muddy to the point that, despite my leanings, I began to question my early conclusions. Much of the opposition has been tied to questions about scientific data, such as wind pattern data from Great Falls, Mont., more than 100 miles north of the cement plant. Opponents have also fastened on whether this sort of permit would be allowed in Switzerland, where Holcim is based.

I first called one of the Gallatin County Commissioners who leans towards environmental stewardship. He said he’d read the reports, gone to the meetings and visited the cement plant. "But I don't see the evidence." Next I called the DEQ. I asked him if the grassroots opposition had given him pause.v "We're not idiots," he said. "We are going to make sure our math is right. We're revisiting the weather modeling. We're taking the health risk concerns brought up by doctors very seriously. We know that, no matter which way our decision goes, we'll likely end up in court. We need to get it right."

Next, I called the cement plant manager, who quickly said, "People are right to ask hard questions. But they need to accept facts when they get them." He said that at the hearing someone asked if this would be allowed in Switzerland.

"The answer is yes. Tires, along with other waste stream products, are burned routinely in cement kilns there." He pointed to cement plants in Texas and Oklahoma burning tires and other wastes, that had undergone just this sort of public scrutiny, and that are subject to stringent controls, that now receive environmental awards for reducing their emissions.

Something else started to bother me. Undercurrents of irony and hypocrisy kept bubbling up in this stewpot of controversy. It turns out that about one-third of the cement produced at this plant, some 90,000 tons, is sold within 100 miles. This "tainted" product is briskly being poured into the foundations of new homes where it supports the construction economy spurred by the quality-of-lifers coming to the Gallatin Valley. Yet these are the same folks contractors are so worried will stop building if they get a whiff of sullied environment.

For another, the "pristine" air and landscape touted by tire-burning opponents may not be all that it's cracked up to be. "The numbers in the Gallatin Valley aren't really that great," my DEQ contact said. "Agricultural crop burning alone puts more pollution in the air than the cement plant ever will. Not to mention improperly vented wood stoves. Not to mention diesel fumes from all the trucks and SUVs everyone drives."

In the end, I'm put off by the stridency, exaggeration and selective reasoning in this debate, including that of some of my friends. Doctors point to the likelihood of leukemia and learning disabilities; contractors predict the end of their business; activists conjure images of an 84-mile-long truck convoy bringing waste tires to the valley. This sky-is-falling outcry undercuts what is a real and valid debate.

There is, certainly, cause for concern. I remain worried about tire-burning, especially coming from a foreign-owned company with a less-than-stellar environmental record. I don't entirely trust the Montana Department of Environmental Quality, which, over recent years, appears to have evolved into more of a "rubber-stamp" agency, and away from acting as environmental watchdog.

My conclusion is that the light of truth is a narrow beam indeed, and what it illuminates depends entirely on who holds it. What's more, it's disquieting to find that I'm just as prone as the next person to see only the small circle of illumination that confirms my preconceived notions.

Alan Kesselheim is a contributor to Writers on the Range (hcn.org), a service of High Country News in Paonia, Colorado. He writes in Bozeman, Montana.