By Malia Mattoch McManus
HONOLULU (Reuters) - Officials tracking volcanic lava creeping through a forest toward homes on Hawaii's Big Island have issued a voluntary evacuation notice for residents with existing health conditions who might find themselves abruptly cut off from medical care.
Residents in the affected Puna district were warned on Tuesday that "medical services and supplies will be severely limited and emergency medical response time may be significantly delayed" if the lava flow crosses the area's main roadway.
Health officials have previously warned of the effects of heavy smoke from trees burned by the molten rock.
A mixture of gases and fine particles released as the lava sets vegetation on fire could cause breathing difficulties, especially for individuals with chronic respiratory conditions, the state Health Department and American Lung Association said.
Civil Defense officials and the Federal Aviation Administration on Monday imposed flight restrictions over the lava stream, which began oozing from Kilauea Volcano on June 27, due to congested air traffic from sightseers and the media.
The flow came to a standstill in late September but resumed its slow crawl forward last week and has covered 85 to 110 yards (meters) since Tuesday, according to the Hawaiian Volcano Observatory.
The leading edge of the flow was about a mile (1.6 km) from the outskirts of Pahoa village, a historic former sugar plantation consisting of small shops and homes with a population of about 800 people.
It was also about 2 miles (3 km) from Highway 130, a major route traveled by as many as 10,000 automobiles a day. About 4,000 people overall live in the residential communities that the lava is approaching.
The lava flow initially prompted some residents of the Kaohe Homestead subdivision to flee as it crept toward their homes. It then cut through vacant areas in the homestead last month as it veered toward the much larger town of Pahoa.
Officials have said that thousands of people could end up isolated and forced to take congested gravel roads if the flow blocks Highway 130.
The flow's leading edge is about 40 yards (meters) wide, large enough to destroy homes in its path. But it posed no immediate danger to local communities, and no general mandatory evacuations have been ordered, civil defense officials said in a statement.
The Kilauea Volcano has been erupting from its Pu'u O'o vent since 1983. The last home destroyed by lava on the Big Island was in the Royal Gardens subdivision in Kalapana in 2012.
(Editing by Steve Gorman and Sandra Maler)