BEAVER, W.Va. — The National Institute for Occupational Safety and Health plans to ask manufacturers to propose two new types of emergency air packs for underground coal mines.

NIOSH official John Kovac said the agency wants proposals for hybrid air packs, or self-rescuers, that combine the oxygen-generating devices used today with filter self-rescuers that scrub toxins but do not provide oxygen. Filter self- rescuers used to be used in coal mines, but today are limited to other underground mining operations.

NIOSH also wants proposals for air packs that allow miners to swap out chemical cartridges that generate oxygen and remove carbon-dioxide. Today, miners must switch to a new air pack if it stops working.

Kovac told about 40 representatives of mine operators, self-rescuer manufacturers and others that a request for proposals will come shortly, depending on funding from Congress. His remarks came during a daylong meeting about the next generation of self-rescuers at the National Mine Health and Safety Academy in Beaver, W.Va.

Emergency air packs have become a critical issue since fatal accidents at the Sago and Aracoma Alma No. 1 mines in West Virginia in January and at the Kentucky Darby mine in May. Most of the miners killed in those accidents died of carbon monoxide poisoning when they were unable to escape.

All wore the No. 1 brand of air packs manufactured by Monroeville-based CSE Corp. The federal Mine Safety and Health Administration says tests shows air packs recovered from those disasters still generated oxygen and therefore were in working order. But Sago survivor Randal McCloy Jr. and others say some of the devices failed.

Kovac also said NIOSH is close to proposing new standards for certifying self-rescuers for use in coal mines. The idea was first proposed by a NIOSH engineer in 1999, but is being revisited. Currently, the government requires devices to provide one hour of oxygen, but the new standards will focus on how much oxygen the devices provide.

"The standards themselves represent a shift in thinking from duration to capacity," Kovac said.

NIOSH plans public hearings on the idea in September and October in Washington and Denver. The hearings are the first step toward developing new standards, Kovac said.

Kovac further suggested mandatory inspections of all self-rescuers used at U.S. coal mines. Kentucky recently completed such a sweep and found more than 100 defective devices from mines. West Virginia recently ordered all coal mines to submit detailed inventories of their air packs, a first step toward state testing and certification of self-rescuers.

And like many in the industry, Kovac suggested beefed up training that shows miners exactly what it's like to don a self-rescuer and breathe through it during an escape. "Live application is the surest way of giving a miner firsthand experience what it is like," he said.