The Fairfax Planning Commission is scheduled to vote next week on whether to allow more and higher buildings near Metro stations and in aging commercial areas, part of an effort to increase the number of lively urban centers in Virginia’s largest jurisdiction.

That initiative has triggered an outcry from residents of some of the affected areas, who fear their quiet, suburban communities increasingly will be overrun by traffic, pollution and other big-city problems.

Fairfax County officials say those who are vocally opposing the changes — mostly residents of Reston, Seven Corners and the Baileys Crossroads area — misunderstand how the land-use rules will work. But officials’ efforts to explain themselves have been met with suspicion from civic activists, who say the new zoning will open the door to commercial development that rivals the scope of Rosslyn’s, in neighboring Arlington County.

“I want revitalization, but we don’t want crazy density,” said Carol Turner, vice chair of the Mason District Council, a group of community associations based in the east-central part of the county, adjacent to Alexandria and Arlington.

While she and her neighbors might welcome more or better restaurants closer to their homes, Turner said, “we don’t want 5,000 apartments plopped down, and that’s what we’ll get.”

The proposal, which is slated for a vote by the planning commission on Wednesday, would allow denser development in 22 areas, all of them either adjacent to stations on Metro’s Silver, Orange, Blue and Yellow lines or in older commercial areas along major roads. If approved by the planning commission, the zoning-law amendments would go to the Fairfax County Board of Supervisors, which has scheduled a public hearing on the topic for June 21.

Officials say the zoning changes are necessary because although the county’s comprehensive plan encourages more homes, offices and stores clustered in these areas, the current zoning laws do not allow the density envisioned by that plan.

Opponents counter that the proposed rules will allow overbuilding in some areas. It’s one thing, they say, for the county to allow high-rises around the Silver Line’s new stations. In older areas such as Annandale or Springfield, they say, such density seems sorely out of place.

Clyde Miller, president of the Holmes Run Valley Citizens Association, accused the county of wanting to “unleash this monster” that “threatens our communities.”

In a detailed, six-page critique, he said a need for the zoning proposal “has not been substantiated, its broad scope threatens to damage communities, and it is opposed by a large majority” of those who have spoken up.

Concern centers on the issue of floor area ratio, or FAR, a measurement that planners and developers use to determine density. For example, a 50,000-square-foot building on a 100,000-square-foot lot would have a FAR of 0.5. If that building on the same lot rose to 10 stories, and each floor had 50,000 square feet, the FAR would be 5.0.

Under the zoning proposal, the allowable FAR in the 22 designated areas could rise from 2 or 3 to 5.0 — half of what can be permitted for new buildings in high-rise Rosslyn, just across the Potomac River from the District’s Georgetown area.

The more relevant comparison, said Fairfax County Zoning Administrator Leslie B. Johnson, is to mixed-use developments built on small lots.

She pointed to two projects in Falls Church — an eight-story retail and residential building at 301 W. Broad St., which has a 3.33 FAR, and a six-story office and retail building at 400 N. Washington St., which has a FAR of 3.9. Both projects, if built under the zoning regulations being proposed, probably could add a floor.

Fred Selden, director of the county’s Planning and Zoning Department, said that concentrating development “reduces pressure on surrounding areas.

“They assume we are greatly enlargening development,” Selden said of those who oppose the regulations. “We are not; the sites are much smaller. The county is moving from very large-site development to small-site development.”

Higher density is not a given under the proposed rules; developers would have to negotiate their plans with the county on a project-by-project basis, with at least two opportunities for public comment and review. But the mere possibility of more people, heavier traffic, fewer parking spaces and more-crowded schools was enough to trigger a flood of emails, phone calls and letters of protest.

After a May 25 public hearing by the planning commission at which eight of 11 speakers opposed the proposed regulations, commission member Tim Sargeant asked for a delay of the panel’s vote from May 26 until next Wednesday. He said he wanted to make sure the package of proposed changes appropriately reflects the county’s goal, which is to harmonize the comprehensive plan and the zoning laws.

At the same time, county officials say they are frustrated that many of the residents’ concerns seem to be misplaced. For example, Selden said, there’s a “misconception . . . that because there is a maximum FAR, everybody will push to go to the maximum.”

At the May 25 hearing, commissioner James Hart said he was struggling “with a mountain of letters and emails. Many of [those writing in] seem to be bitterly opposed to something nobody has proposed, but it takes on a life of its own.”

The zoning proposals have the support of Supervisor Penelope A. Gross (D-Mason), whose district includes some of the most vocal critics. Many of them have clashed with the six-term lawmaker in the past over the scope and pace of development, and several backed Mollie Loeffler last year when she mounted an independent challenge against Gross.

Creating places where people can live, work and play, in areas where they can walk, bike or use public transportation, is a key part of revitalizing deteriorating areas and generating new tax revenue, Gross said.

“In most areas, stable suburban neighborhoods are anticipated to remain suburban,” she said of the proposed zoning changes. At the same time, “the commercial centers will have residential amenities, too.”

Critics regard those statements with unbridled suspicion. In addition to concern about overbuilding, they also are unhappy that the zoning-law amendments would allow half of the open space required for projects to be on the roofs of new buildings, which they said could limit public access.

“We’ve had all this history of county government. . . . They get some developers enticing them and they get their way, and we’re stuck with overcrowded schools and streets,” said Jeff Longo, who is president of the Sleepy Hollow Manor Citizens Association and supported Loeffler during her campaign.

Turner, from the Mason District Council, said she and other opponents of the rules changes see no reason to think that the county has their best interest in mind.

“We’re not listened to. We don’t believe what they say they’re going to do,” Turner said. “If they have this tool, they’re going to use it.”