August 29, 2001 11:00 pm

By Alice Perry Linker

Observer Staff Writer

Stable weather conditions with light winds aloft have contributed to the smoke that drifted into La Grande over the past two days.

Mary Smith of the National Weather Service in Pendleton said the winds at about 5,000 feet were predicted to blow north to northeast at 5 to 8 mph Wednesday morning and early afternoon. The surface winds were predicted to be northwest between 5 and 15 mph per hour.

Weve had very stable conditions, Smith said. When we have those conditions, the air mass will sink it doesnt mix.

Smoke sank and drifted into La Grande and Union about noon Wednesday.

Ruth Zemke of the Smoke Management Center at Imbler said Wednesday afternoon that the culprit was a test fire ignited about 11 a.m. near Alicel.

At first the smoke went up; then it tipped and spread and dropped down,

By noon the valley area between Highway 82 and Union was lightly covered with a smoky curtain.

The meteorologist from the Department of Agriculture in Salem said this morning that winds were blowing northwest at 3 mph at noon Wednesday. The wind speed varied from 3 to 6 mph until about 2:35 p.m. when it was recorded at 7 mph at the Union County Airport.

The Department of Agriculture had predicted transport winds at about 10 mph throughout the afternoon hours.

Scott Fairley of the Oregon Department of Environmental Quality reported that at 11 a.m. Wednesday, the nephelometer in La Grande showed a .4 concentration of particulates. Between noon and 1 p.m. the level had risen to 1.6, he said.

When the reading gets higher than 3, the federal standards kick in, Fairley said.

A reading of 1.6 is within the level of compliance, although the particulate count is higher than the standard for good health, Fairley said.

At this level it would be problematic for people with respiratory problems, and they may want to take precautions, Fairley said.

The La Grande DEQ office had received no complaints about smoke Wednesday afternoon, he said.

The state office of the DEQ in Portland reported in a news release Tuesday that the state office has been receiving calls from people asking about the health impact of smoky air.

Smoke is composed of tiny particles of particulate matter that can be harmful to breathe, particularly for children, the elderly and those with cardiovascular and respiratory disease, the report stated.

Zemke said that additional agriculture burns in the north end of the Grande Ronde Valley, where she said the winds were more favorable, were planned for late Wednesday.

The Smoke Management Center at Imbler uses a variety of tools, including weather forecasts from the Department of Agriculture and a weather balloon, to determined if conditions are right for burning.