Layoffs and other consequences of a slowing economy sent Virginia's unemployment rate up to 4.1 percent in August, the Virginia Employment Commission reported yesterday.

Although the state unemployment statistics are not adjusted for seasonal factors, making month-to-month comparisons somewhat suspect, officials said that the August rate was a full percentage point higher than it had been in the same month in 1989. It remained below the comparable national rate of 5.4 percent.

The unemployment rate for Northern Virginia was the lowest of any region in the state at 2.3 percent, but even that was more than half a point above its 1.6 percent level of a year ago.

"The economy is not growing as fast as it was last year," said William Mezger, a research economist at the employment commission.

In Northern Virginia, many of the jobs lost have been in construction -- employment in that industry is down from 66,000 in August 1989 to 55,300 in August of this year -- although defense contracting and electronics also are down or growing slowly.

The number of unemployed Virginians rose 8,700 over the month to 131,200.

Mezger cited layoffs at various auto, tire and component plants in the state.

The crisis in the Middle East also had an indirect impact on Virginia: The Hampton Roads area's economy suffered because fewer military personnel were around to patronize restaurants and clothing stores.