Dr. Scott Hurst said that even more dangerous than the PM2.5 and PM10 air pollution particles that are monitored and regulated are "ultra-fine" particles smaller than 2.5 microns. A report shows that the smallest pollution particles pose the greatest danger because of their chemistry and surface area.

Moench cited reports that compared ailments caused by air pollution as similar to those caused by smoking. Some of the worst effects happen when unborn children, and the very young, are exposed to air pollution, he added — people who have never smoked.

"Our children and grandchildren deserve nothing less than our combined best efforts," he said.

Board member Wayne Samuelson said he was disappointed to hear the physician group "take a position that could be construed" as the stance that one might as well smoke because it's no worse than breathing in a polluted city.

"Take the cigarette comparison out of it," he urged. Smoking is a separate issue, Samuelson added.

Rick Sprott, executive director of the Utah Department of Environmental Quality, said state officials regard groups like the physicians as "very strong allies." In the February meeting, he added, the concern was about the fact that the smoking and air pollution comparison was a metaphor.

Sprott added, "I think we're on the same page."

Asked for a comment on the physicians' presentation, Packham said air pollution worse than the federal air quality standards poses unacceptable health risks.

"They are unacceptable to me as a toxicologist and as a regulator. The risks from air pollution are not zero, and they are not acceptable, but they are also not equivalent to smoking."

Packham added that he hasn't spoken directly with Moench about the group's statements or comparisons, "and I look forward to discussing this issue with them on a scientific basis."

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