Formed Concrete and IAQ ( Radon from concrete)


Concrete Forms and IAQ

A product commonly referred to as fly-ash has been used as an additive to concrete
for a number of years. It is a by-product of the burning of coal in power plants
and can contain a variety of compounds including mercury, chromium, lead, nickel
compounds, and other toxic elements. Fly-ash is usually added to create a more
flowable concrete. In some areas it is even added to concrete used in commercial
building structures.

Recent discoveries in several East Coast buildings, European buildings, and
even high-rise office buildings in Hong Kong have shown a rise in toxic contaminants
in the indoor air. This has been shown to be in direct relation to the presence
of a fly-ash containing some of those same compounds, which was added to the
concrete pours.

One of the most dramatic situations involves high-rise office buildings in
Hong Kong. It has been the practice for many years to include some fly-ash in
concrete pours. As a result of this as well as the granite aggregation in the
concrete, many high-rise office buildings, which are manufactured of reinforced
concrete construction, are found to be "hot" with radon. When the
HVAC systems are switched off overnight or during weekends, the radon concentration
in the building rises rapidly and continuously. Night workers and even those
who come into work on Sundays are then exposed to dangerously high radon levels.

Unfortunately once a building's concrete has been identified as a source of
these problems, there is little that can be done. Replacement is not an option,
and there is no proven method of encapsulation to resolve the emissions.

In this case, an old IAQ adage appears to define the remedy. It says, "Dilution
is the solution to indoor air pollution!" When the source can't be found,
or as in this case cannot be removed, increased dilution appears to be the best
control mechanism.

Next Week - A Building Air Quality Action Plan

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