Smokers in Fairfax and Arlington counties could soon find buying a pack of cigarettes more taxing than they had thought.

Last month, the General Assembly voted to increase cigarette taxes from 2.5 cents a pack to 30 cents over the next two years. Now officials in Fairfax and Arlington are moving to boost cigarette taxes in their counties, the first such increases since 1970.

Yesterday, the Arlington County Board voted to raise its cigarette tax from a nickel a pack to 20 cents beginning Sept. 1, the same day the state increase starts.

And tomorrow, the Fairfax County Board of Supervisors will consider taking the first step toward also quadrupling its 5-cents-a-pack cigarette tax.

Of Virginia's 95 counties, only Fairfax and Arlington are allowed by the General Assembly to levy their own cigarette taxes, although Virginia law prevents them from exceeding the new state rates: 20 cents a pack this year and 30 cents next year.

Virginia lawmakers approved increases of 17.5 cents (to 20 cents a pack) this year and 10 cents (to 30 cents a pack) next July 1. When the state's dime-a-pack increase goes into effect next summer, Fairfax and Arlington also would tack on 10 cents.

All cities and towns, meanwhile, are allowed to add their own levies to the state's, and many have. On July 1, cigarette taxes went up in Falls Church (to 50 cents a pack), Manassas (to 50 cents a pack) and in Dumfries (to 30 cents a pack).

Arlington and Fairfax officials often complain that their ability to raise revenue is limited by state lawmakers. The cigarette tax offers them a chance to bring in extra money.

"We've been looking for this for a long time," said Barbara Donnellan, Arlington's director of management and finance, who said the cigarette tax would help the county diversify its tax base. "Local governments are limited on the taxes they can raise, and this gives us that opportunity."

Arlington officials estimated that the county would raise an additional $1.4 million this fiscal year from the cigarette tax, money that will be used for property tax relief.

The measure before the Fairfax Board of Supervisors would schedule an Aug. 2 public hearing on the proposed cigarette tax increase. If approved, it would also take effect Sept. 1.

Fairfax County brings in nearly $2 million a year from its nickel-a-pack cigarette tax, officials said, a figure that has remained relatively constant over the years despite population growth. County budget officials estimate that Fairfax would collect $11.5 million a year if the county approves an increase of 20 cents a pack this year and 10 cents a pack next year.

Unlike Arlington's measure, the Fairfax proposal does not specify that the additional revenue go toward property tax relief, but county officials said that seems likely.

Even with the higher taxes, officials said they do not expect cigarette purchases to decline significantly because smokers still would pay less for cigarettes in Fairfax than in some other Northern Virginia jurisdictions. Fairfax City, for example, already charges a tax of 50 cents a pack.

"I don't think the increase is large enough to cause that much of a decrease in sales," said Ron Smith, administrator of the Northern Virginia Cigarette Tax Board, which administers and collects the taxes in the area. "I think a lot of smokers buy for convenience as opposed to actual price."