HALEMA'UMA'U, Hawai'i — Scientists, civil defense and Hawai'i Volcanoes National Park officials are grappling with a new set of problems as the summit of Kilauea volcano pumps out an unprecedented amount of gas and volcanic ash.

The trade winds have helpfully pushed pollutants away from most populated areas since Kilauea nearly doubled its gas emissions earlier this month, but it is only a matter of time until the winds shift.

When that happens, higher levels of sulfur dioxide and other particles may be blown into nearby communities, which include Volcano Village and the subdivisions in Upper Puna, posing a potential health threat. People with respiratory problems such as asthma, bronchitis and emphysema would be particularly at risk.

The unexpected increase in sulfur dioxide production at the summit of the volcano has officials at the state Department of Health scrambling to develop new guidelines to determine when communities may be at risk from short-term spikes in the emissions, and how great those risks may be.

Those guidelines aren't expected to be complete until next week, but there are some signs that suggest which communities could be affected.

On March 19, the 24-hour average levels of sulfur dioxide in Pahala exceeded federal ambient air quality state guidelines in what amounted to the equivalent of a bad pollution day in an urban area. That prompted the state Department of Health to issue an advisory to warn residents, especially those who have respiratory problems.

Pahala is 20 miles southwest of Halema'uma'u, which suggests communities such as Volcano, Glenwood, Kurtistown, Mountain View and even the sprawling Puna subdivisions such as Hawaiian Acres may feel the effects of the changes at Kilauea when the winds blow from the southwest.

According to the 2000 Census, those communities have a combined population approaching 10,000, and all are within 20 miles of the new vent that opened at the crater and dramatically increased the sulfur dioxide emissions from the volcano.

Big Island Mayor Harry Kim acknowledged yesterday that scenarios are being studied that could include evacuations of the 800 workers at Hawai'i Volcanoes National Park and the surrounding area if the air quality deteriorates dramatically.

"Our responsibility is to assess what is the risk to people and to take appropriate actions," he said. "The worst-case scenario obviously would be if in areas of the park the SO2 reaches a level that we will advise evacuation of all people. Hopefully that will not be, but obviously that is a scenario based on wind conditions that could be for the areas abutting the national park."

Asked if that scenario could include Upper Puna areas such as Mountain View, Kim said, "I said areas abutting the national park. Upper Puna abuts the national park."

LAYER OF ASH

Pu'u 'O'o on Kilauea's East Rift Zone has been pumping out about 2,000 metric tons of sulfur dioxide per day for years, while only about 200 tons per day was being released at Halema'uma'u at the summit. The sulphur dioxide emissions from the summit began to climb late last year, and by March 13 had climbed to record levels of 2,000 tons per day.

The emissions at Pu'u 'O'o have held steady since then, while the gas released from Halema'uma'u has ranged from 600 to 2,500 tons over the last few days. Overall, the emissions from the volcano have roughly doubled, scientists said.

In Wood Valley, a community about five miles north of Pahala, the effects of the change in the eruption are obvious. A layer of ash has been dusting the hoods of vehicles and other surfaces, and when the wind is wrong, the vog (volcanic smog) is thick.

Claudia McCall, who operates a cut-flower farm with her husband in Wood Valley, said the fumes and vog have damaged leaves on some of her crops, and said her roses seem particularly sensitive. If the summit emissions continue, she said, she may have to give up on roses, which will severely hurt her business.

"I'm actually more concerned with the health of the people," she said of the fumes. "When you can taste it, you know it's not good to breathe it."

John Peard, project manager for the Health Department's Hazard Evaluation Emergency Response Office, said the sulfur dioxide levels drop with distance and time so he does not expect significant levels of the gas to drift to other islands or even to Kailua, Kona. But he said scientists are still trying to gather data to determine what level of risk might be faced by closer Big Island communities.

MOST TOXIC OF GASES

The focus is on sulfur dioxide because it is the most toxic of the gases, and monitors are also tracking the aerosol particulates produced as the SO2 breaks down. It is those particles that are generally known as "vog."

The effort to develop new guidelines has focused on the most sensitive populations, such as people with pre-existing respiratory illnesses. "Those sensitive individuals are much more prone to adverse effects from the sulfur dioxide than healthy individuals or individuals without those preconditions," he said.

The state has guidelines to protect the population from long-term exposure to sulfur dioxide, but it now needs to draft guidelines for short-term spikes in the gas "to protect individuals as quickly and efficiently as possible," he said.

There are 10 fixed monitors measuring the air quality in the area and as far away as Pahala, and four mobile monitors available to gather additional data, Peard said. The national park and county fire department have ordered more air monitors, and a U.S. Army civil support team is bringing in another six air monitors that will contribute additional data, he said.

The extra monitors will provide scientists with more data about how the gas dissipates, and where the risk is greatest. With constant changes in the winds and the composition and volume of the gas, "it's an incredibly complex combination, and to predict it is a real challenge, but that's where we're going. We want to be able to predict as best we can," Peard said.

A seven-member team assembled by the National Park Service has been at the park for a week helping parks officials plan for various contingencies, and the Federal Aviation Administration has closed the air space below 4,000 feet for three miles around the vent because of the risk the ash and smoke present to aircraft.