Air Samples Dim Hope In New Zealand Mine Rescue Effort

Air released from drilling into a New Zealand mine to reach 29 workers trapped underground contains high levels of carbon monoxide and methane but little oxygen, according to police officials.

Authorities refused to speculate on whether the miners could survive breathing that air, but they repeated earlier concerns that the situation is growing increasingly grim.

""Obviously, with the passage of time, optimism diminishes,"" Gary Knowles, superintendent of the Tasman Police District said, at a Wednesday morning news conference.

Authorities said the two camera-bearing military robots sent into the mine had found a worker's helmet with its light still on, but no sign of life. The helmet, police said, was dropped by one of the two miners who escaped the original explosion.One of the robots had broken down earlier Tuesday but was back online, said Peter Whittall, CEO of Pike River Coal, which owns the mine. Whittall said a third robot was on its way to the site.

One the units reached a ""fresh air base"" and found nobody there, he said.

The 29 men, ages 17 to 62, have been missing since Friday, when an explosion ripped through the Greymouth mine. Most of the miners are from New Zealand, but the group also includes Scotlanders and South Africans.

The missing men are believed to be spread throughout the mine, with perhaps half trapped in one area. Authorities have said there is drinking water in the mine, but it is likely none of the trapped miners brought more than a day's worth of food on the day of the explosion."