WASHINGTON -- In the hours before they suffocated, the miners who were two miles inside the Sago Mine tried to build a shelter to keep out the bad air and keep in the good.

The same month, 72 miners trapped in a potash mine in Canada survived inside a steel rescue chamber, an event that turned the focus of mining regulators to creating safe spaces for miners stranded deep in the earth.

Last week, industry and government officials gathered at the National Academy of Sciences here to explore how to deal with the issue. At one point, representatives of various equipment vendors presented their wares, an occasionally poignant reminder of seemingly simple things that could have saved the 11 Sago miners who, unaware they could escape, huddled inside the mine and slowly asphyxiated.

"We could have given them air, food and water for 96 hours, in time to be rescued," said Ed Roscioli, of ChemBio Shelter Inc., of Allentown. He showed a tape of a self-inflating chemical-biological hazard shelter he hopes mine officials will consider.

The inflatable shelter, designed to protect troops from chemical attack, was one of an array of designs, including corrugated steel boxes and ideas as simple as cutting notches into coal pillars, sealing them with airtight doors and feeding air through holes bored from the surface.

"The simple, cost-efficient, just plain effective things, those are the things we are most likely to mandate first," said David G. Dye, the acting head of the Mine Safety and Health Administration.

The concept of mine rescue chambers in North America dates to 1928, after Canadian miners died in a series of accidents. By the 1930s, Canadian mine owners were voluntarily installing underground chambers, often carved out of the rock inside the mines. Today, most Canadian mines have rescue chambers, said Alex Gryska, a mine rescue manager for Ontario's Mines and Aggregates Safety and Health Association, a quasi-governmental agency.

"The Americans have been able to put a man on the moon. My God, they ought to be able to build a refuge station that ought to offer safe haven to miners. I think it's doable," Mr. Gryska said.

But Canada's mines differ markedly from America's in two respects: Most are far deeper than U.S. mines and only two of them are coal mines, meaning fires are less likely to spread.

"You need a pretty solid barrier of some type for coal. That's why we haven't pursued it in the past," said David M. Young, president of the Bituminous Coal Operators Association. "Historically, the best method has been to get out as fast as possible."

Miners, though, have not always fled, often because passageways are blocked, either by roof falls or dense smoke. The case of the Sago miners bore some haunting reflections of a case 66 years earlier, when a group of miners inside the Sonman Mine in Portage, Cambria County, built a makeshift barricade in hopes of closing off bad air and died for lack of oxygen seven hours later. In all, 63 miners died in the Sonman incident, few of them from the explosion.

Thirteen miners gave up on building a barricade in another section of the mine and, instead, fled to the surface.

One misgiving mine safety officials have expressed about shelters is that they might prompt miners to flee to underground refuge instead of the surface.

"Getting out is the first thing. If you can, you get out," said Kelvin Wu, a researcher in MSHA's Pittsburgh office.

While the inflatable tent displayed at the National Academy of Science forum posed practical issues for coal mines -- such a device would not easily resist blasts or flames -- Mr. Wu sees a role for some of the portable chambers displayed, if they are used in conjunction with a series of hardened, permanent chambers along mine routes.

Mr. Wu and Randy Berry, a researcher from Foster-Miller, a private consulting firm, have advocated a decidedly low-tech system for rescue chambers. Mr. Wu advises using a continuous mining machine to dig out a notch in a coal pillar, then either drill a ventilation hole from the surface or stock bottled air and breathing devices.

Mr. Berry was co-author of a 1983 research paper that laid out similar theories, including closing off cross-cuts, the passageways between coal pillars, with air-tight doors.

"The emphasis in all our designs was to use off-the-shelf materials whenever possible," Mr. Berry said. He suggested the construction of permanent chambers dug into the mine along the escape route.

"It should be located on the way out," Mr. Berry said. "We don't want folks to go the wrong way."