Several construction workers excavating for an underground parking garage in Fairfax County, Va., in 1987 hit a naturally occurring asbestos vein in the rock and suffered side-effects from asbestos dust released during drilling on the site.

The county health department convinced county leaders to pass an ordinance regulating construction work in asbestos prone areas.

“In an undisturbed natural environment, these fibers are locked in place within the rock and represent no health hazard. However, when disturbed, such as during construction, these fibers are released as a fine dust which can readily be inhaled into the respiratory system,” according to James Dusek, Air Pollution Control Specialist with Fairfax County who co-authored the ordinance. “Long term exposure to such conditions could lead to debilitating or fatal diseases.”

Fairfax County health department workers have also concluded that the asbestos dust could blow off the construction site in dry, windy conditions and pose a “serious health hazard” to neighbors.

The ordinance requires dust control at construction sites in asbestos prone areas of the county, which can be as simple as a well aimed garden hose during drilling or equipping machinery with misters and foggers.

The ordinance calls for numerous precautions. Risks involved must be clearly posted for workers. Access to the site must be controlled. Workers directly exposed must wear protective gear and go through a decontamination trailer before leaving the site. Tools, vehicles and equipment also have to be decontaminated.

Soil and rock removed from a site has to be specially disposed, such as wetting down the load to keep it dust free during transport to the landfill. Clean soil must be hauled in to cover the site to a depth of six inches following the construction project.