It was 1977 when American coal miners were first required by law to carry a self-rescuer, a portable breathing device with a one-hour supply of oxygen.

Coal was king then, and the new federal Mine Act was ushering in a series of safety reforms, spurred by the deaths of 78 miners in an explosion at the Consol No. 9 mine in Farmington, W. Va.

Nearly 30 years later, coal is king again, says Dennis O'Dell, administrator of occupational health and safety for the United Mine Workers of America. But the technology that coal miners need to avoid and escape disasters like the one that killed 12 men at the Sago Mine in Tallmansville, W.Va., last week has not improved much over the years.

"Miners are using 20-year old technology -- it's been that long," Mr. O'Dell said. "In that stagnant period, the industry kind of died, and very little was being worked on."

Market forces have shifted, experts say, rendering miners' safety equipment a niche market, and stifling technological advancement.

Communications and navigation systems remain largely unchanged in mining operations. Global positioning systems do not work underground, experts say. Alarms, pagers and hard-wired telephone systems are limited in their coverage and vulnerable to fire damage and power outages.

Some self-contained self-rescuers have been recalled because of holes in the air bags, leaks of caustic chemicals, or hoses that rot and turn to dust in the containers. Some design improvements have been made, but the technology is largely the same.

One of the reasons for the innovation lag is that coal mines in the United States today are more productive than ever, mining coal about 20 times faster than they did just 15 years ago, said Lewis Wade, senior science adviser for NIOSH, the National Institute for Occupational Safety and Health, and former head of its mine research program.

With the industry's advancements in automation, the ranks of coal miners have dwindled. Companies that were founded on innovations in mining safety have switched their focus to firefighting equipment, crowd evacuation gear, homeland security and military applications.

"The mining industry is big where you are, but it's very small when it comes to buying power," said Mr. Wade. "It's difficult to compete with manufacturers when those markets are huge."

Pittsburgh-based MSA, or Mine Safety Appliances, was started in 1914 by former rescue engineers for the U.S. Bureau of Mines. Coal miners then used candle lamps, which became deadly when a worker encountered a pocket of methane gas. The company's first product was a battery-powered cap lamp. The founders approached inventor Thomas Edison, who was working on battery technology at the time.

"He didn't see any value in [the battery-powered miner's cap lamp] at first," said MSA spokesman Mark Deasy. "Later in life, he'd say that was the one invention that did the most for humanity."

Now, even though it is in the company name, mining accounts for less than 5 percent of MSA's business. It concentrates on a wide range of protective equipment such as hardhats, firefighter helmets, respirators, self-contained breathing apparatuses, clothing, and hearing, eye and face protectors.

MSA exited the self-contained self-rescuer business a year and a half ago in North America.

"The market had a bearing on it," said Mr. Deasy.

In the wake of the Sago disaster, the focus narrowed to the self-rescuer, one of the last resorts of survival and escape.

Greene County native Joe Main, former head of United Mine Workers Department of Health and Safety, was in Upshur County, W.Va., on his own this week to draw attention to safety recommendations made after explosions in an Alabama mine killed 13 people in 2001. He says those recommendations have been ignored and, as a result, 12 men died in Sago.

Mr. Main sees tragic similarities between the Alabama and Sago disasters. Both were explosions that poisoned the air, delaying rescue attempts. Both explosions made communications between the miners and rescuers impossible.

Mr. Main was part of the group that designed the SR100, a belt-wearable breathing device that many miners today wear. These supply about an hour's worth of air.

"Even with that, that's not enough air to get those miners out of these circumstances which we all know now they find themselves in," Mr. Main said.

MSA supplies two types of self-rescuers to mines in other countries. One is a filter self-rescuer, which converts exhaled carbon dioxide into oxygen. Its useful service life depends on the level of carbon monoxide in the air; if the air has a high concentration of the poisonous gas, the miner might get an hour of air, maybe even less.

The other is a self-contained self-rescuer -- a larger, heavier device that supplies oxygen through a chemical reaction. It is designed strictly for escape purposes, said Mr. Deasy.

"Mine workers can keep it cached somewhere in the mine, and in an emergency can take it out, don it, and get the heck out of there," said Mr. Deasy.

The self-contained self-rescuer provides an hour of air to someone breathing at a "moderate to high" rate, he said. At rest, with controlled breathing, a miner may get 4 to 5 hours of air out of it.

According to Mr. O'Dell of the UMW, there should always be enough oxygen for miners in jeopardy to be able to reach the surface, with self-rescuers placed strategically throughout the mine.

"If it takes me six hours to walk outside, I should be able to find a new unit, change out my unit, and don the new unit," he said.

NIOSH conducts scientific research and makes recommendations for preventing work-related injuries and illnesses. The single biggest advance it is pursuing is the personal dust monitor, or PDM -- 20 years in the works. Coal dust causes Black Lung disease, and can also be a factor in mine explosions.

With current technology, a mine employee takes a dust reading by exposing a piece of filter paper to the atmosphere and sending it away for analysis. Two weeks later, the results come back, said Mr. Wade. The new PDM clips to the miner's belt and measures the coal dust levels immediately. Prototypes are being deployed in mines, so far with great success.

NIOSH is also exploring through-the-earth communications systems, using the rock itself as a conduit.

"Technically, that's a ways off," said Mr. Wade. "The realistic thing to do now is to harden the systems we do have, protecting them from a fall of ground or a fire."

Advances in mine safety technology also depend on regulations, and enforcement of those regulations, said Tim Baker, the UMW's deputy administrator for occupational safety and health.

The safety requirements for self-contained self-rescuers have been pretty much unchanged over the past two decades. Early generations were big and heavy. Mine operators with federally approved storage plans began to allow workers to store them nearby, in man buses or escape ways, rather than carry them, Mr. Baker said.

"In effect, what that did was stop the technology," he said. "Why would I want to spend any more money on [better self-rescuers] when we're already in compliance?"

With retirements and other kinds of attrition, the mining industry has also been losing its specialist mine inspectors, said Mr. O'Dell.

"It used to be, a mine had a ventilation specialist, a roof-control specialist, an electric specialist," Mr. O'Dell said. "[Now] they've got these specialists being asked to perform other duties, and the system has lost its efficiency."

The past two weeks, mining experts and mine safety gear manufacturers were all talking hopefully about a relatively new technology called a refuge chamber.

Just one day after the explosion at Sago mine, and half a world away, three miners were saved from a fire in an underground nickel mine in Tasmania. Trapped behind a burning truck, the men waited for 8 hours in the oxygen-supplied metal chamber, sealed off from the thick smoke.

Draeger Safety Inc. supplies the refuge chambers. Mandated by federal law to be used in metal and nonmetal mines but not coal mines, the chambers are big metal boxes that can accommodate 20 people and supply them with oxygen for 24 hours.

In an emergency, miners enter, sit down and turn on the oxygen cylinders. The chamber both absorbs exhaled carbon dioxide and creates a slight overpressure so poisonous gases can't enter, said Draeger Safety President Wes Kenneweg.

In those metal and nonmetal mines, workers dig out a section of rock for the chambers. Using the refuge chambers in coal mines is more problematic, but, Mr. Kenneweg said, "not outside the realm of possibility."

"In coal mines, the problem is the process moves so fast, it's difficult to keep up with where all the miners are located," he said.

The company, which has its U.S. headquarters in Pittsburgh, is also developing a smaller, lighter self-rescuer.

Over the decades, there have been advances. There are now lightweight and easily installed support systems to shore up cave-ins, once the principal source of mining fatalities, said Mr. Wade.

Some larger mine operations have atmospheric monitoring systems, with sensors placed throughout the mine to detect methane levels, smoke and carbon monoxide. All the information is fed into a computer on the surface, and dispatchers relay information about system failures to the teams below ground, said Mr. O'Dell.

Mining experts hope some good will come from the deaths at Sago Mine. Large-scale mine fatalities have historically brought safety improvements and other reforms.