The Illinois EPA will use several criteria to determine which houses will be sampled. The criteria will
The homes will be close to either Source Area 4 or Source Area 7. If sample results show that
underground VOC vapors are entering the houses located closest to the sources of contamination,
the Illinois EPA may later sample additional houses farther from the sources.
Several weeks before the indoor air sampling, the Illinois EPA will conduct a soil gas survey near
Source Areas 4 and 7. The soil gas survey will consist of pushing a probe into the ground eight to
12 feet, withdrawing soil gas (air between the soil particles) and analyzing the gas for VOCs.
These results will be evaluated using the U.S. EPA draft guidance to determine if more than ten
houses need to be sampled.
The Illinois EPA prefers to resample homes that were sampled in 1992 and 1993, if the homes
meet other criteria. Comparison of 1992 and 1993 results with 2003 results would help determine
if concentrations have changed over time.
The Illinois EPA will exclude homes where a resident smokes, because tobacco smoke contains a
small amount of VOCs. The Agency will also exclude homes where a resident works in an
occupation that uses VOCs, such as solvents. The presence of these chemicals could invalidate the
sample results. Also, houses with sources of VOCs that cannot be removed, such as the recent use
of paint, will be excluded.
The Illinois EPA will only sample homes where the homeowners and occupants agree to give the
Agency access to set up monitors inside and outside the house for 24 hours. In addition, the
Agency will need access to collect a soil gas sample outside the house, as close to the house
foundation as possible. Occupants must also agree to ventilate their homes before the Illinois EPA
collects indoor air samples and to refrain from certain activities (such as painting and bringing dry
cleaned clothes into the house) for a specified length of time before sampling begins. Occupants
also will be asked to allow the Illinois EPA to conduct a presampling walk-through of their homes.
During this walk-through, the Agency would identify sources of VOCs, such as household products,
already present in the house.
Is it difficult to evaluate sample results?
Yes. Many of the contaminants found in the groundwater and in the sources of contamination are also
found in common household products such as glues, paints, cleaners, recently dry cleaned clothes,
perfumes, fingernail polish removers, pesticides, carpet and wallpaper glue, liquid detergents, shoe
polish, printers ink, chlorine bleach scouring powders and food packaging material. Monitors set up in
the homes will show whether VOCs have or have not been detected. If they are detected, the monitors
will indicate the concentrations. The monitors do not indicate the source of the VOCs. The task of the
Illinois EPA is to determine if harmful levels of vapors are entering people's homes from contamination
outside the homes, or if vapors originate from household products or materials. Such a determination
may be difficult.
What happens if indoor VOCs vapors are found above levels of concern?
The Illinois EPA does not expect to find indoor VOC vapors above levels of concern. However, if such
levels are found, the Illinois EPA will first attempt to determine the source of the vapors. If the vapors
are from household products or other materials inside the home not related to the Superfund site, the
Illinois EPA will advise the homeowner. The homeowner, then, can take appropriate actions to remove
the source. If the source of vapors appears to be from contaminated underground water or waste, the
Illinois EPA and the U.S. EPA will evaluate appropriate actions to remove the vapors. Actions could
include providing the home with a ventilation system.
Are there harmful levels of vapors in the air outside?
No. The concern is that vapors beneath ground surface may accumulate over time in enclosed spaces
such as homes. During the sampling this spring, one monitor will be placed outside each house sampled
to determine if there are VOCs in the outside air from neighboring industries or other outside activities.
Will there always be a concern about the possibility of vapors entering people's homes from
the contaminated groundwater or underground waste?
Residential Indoor Air Sampling Update - Southeast Rockford Groundwater Contaminati... Page 2 of 4
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