For the last thirty years, we have understood the problems associated with groundwater contamination. So when officials learn that nearby gasoline stations or dry cleaners have leaks, the response is now routine.

There is an attempt to gain source control, which means to stop the leak from occurring, and then there is an effort to clean the groundwater.

End of story? Perhaps not.

As officials are now discussing in New York State relating to a spill that occurred in Dutchess County, questions about vapor intrusion must now be addressed. Vapor intrusion occurs when hazardous chemicals in groundwater become airborne and seep into building foundations.

Nobody has been thinking much about vapor intrusion until now. In fact, there are no federal rules relating to vapor intrusion testing. There are guidelines, but no laws as of yet. Certainly, that will change.

Scientists and regulators are beginning to understand that cleaning the groundwater is often the first part of the process. There must be an analysis of the air quality buildings within the vicinity of the groundwater contamination. In other words, officials must determine whether the contaminants contained in the groundwater have vaporized and seeped into the structures.

Volatile organic compounds are of particular concern. These are substances that easily become airborne and have the potential to enter buildings. Common among volatile organic compounds are degreasers such as TCE and dry cleaning fluid called PCE. These are just two, there are many that are found in groundwater contamination cases.

Many of these chemicals are known carcinogens. Which means that they can cause cancer as well as other diseases. So it will be necessary for regulators to develop standards to determine when people are truly at risk from toxic vapors.

Factors that will have to be evaluated will include the extent of groundwater contamination, issues peculiar to hydrogeology, and structural conditions relating to the buildings. But it will be up to scientists and the regulatory community to inform all of us as to when a detailed vapor intrusion analysis is required.

Common groundwater contamination cases include gasoline leaks, dry cleaner leaks, and discharges from factories. Each of these may contain substances that can become airborne and invade building spaces.

Also, redevelopment projects on former contaminated properties may also have this as an issue. Many landfills around the country are being redeveloped. In those cases, vapor intrusion must be considered. This is particularly important because some contaminated properties are now being redeveloped into homes.

Do you live in an area where there is or has been a known groundwater contamination occurrence? If so, you should be aware of this vapor intrusion issue. Indications are that in some cases, it is not enough to remove toxic chemicals from groundwater. Indoor air quality must also be evaluated.

The information provided in this column is written by Stuart Lieberman,a practicing environmental attorney, and is for general information purposes only. It is not legal advice and should not be used in place of legal advice.

Stuart Lieberman, Esq., and IRED.Com, Inc., will not accept any responsibilty for any reliance on the information in this column or any damages whatsoever resulting from reading this column.