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Brian Rohrig is a science writer who lives in Columbus, Ohio. His most recent
ChemMatters article, “Biomimicry: Taking Inspiration from Nature,” appeared in
the February/March 2016 issue.
It is easy to take for granted the heating systems in our homes. Natu-
ral gas, for example, is a relatively safe clean-burning fuel. If all is work-
ing properly, you have little to fear. Natural gas is mostly composed of
methane and burns according to the following chemical reaction:
CH4 + 2O2 ➔ CO2 + 2H2O
The above reaction assumes complete combustion, where all of the
methane combines with oxygen to yield carbon dioxide and water vapor.
However, if combustion is not complete, then carbon monoxide (CO), a
potentially lethal compound, is produced as follows:
2CH4 + 3O2 ➔ 2CO + 4H2O
No furnace, no matter how efficient, will burn 100% of its methane;
some carbon monoxide will always be produced. This is typically not a
problem if the furnace is properly ventilated and the products are safely
released to the outside. However, if there is a problem with the ventila-
tion, then toxic carbon monoxide can enter the home.
If the flame produced by a furnace is yellow instead of blue, incomplete combustion is occurring, along with the release of copious
amounts of carbon monoxide. Just as the Bunsen burner flame in a
chemistry lab must be blue to ensure complete combustion and the hottest flame, so must the flame in a home’s furnace. The worst possible
combination is a faulty furnace and poor ventilation.
Often, carbon-monoxide poisoning
occurs when gasoline-powered generators are used in the home. These
generators should always be placed
outside. If an oil-burning heater is
installed in the home, it must be
properly ventilated. Also, the burning
of charcoal produces a lot of carbon
monoxide and should never be done
in an enclosed space.
Because carbon monoxide is
an odorless gas, its presence can
easily go unnoticed. Symptoms of
carbon-monoxide poisoning include headache, dizziness, nausea, and
fatigue. Carbon monoxide binds more readily than oxygen to hemo-
globin in red blood cells, effectively displacing oxygen and causing
death by suffocation.
Every home should have a carbon-monoxide detector, which is the
best way to know if unsafe levels of this gas are present. Older furnaces should be inspected on a regular basis to make sure they are
The best strategy to rid your home of noxious chemicals is to open
the windows and allow the fresh air in to displace the stale air. If you
are experiencing chronic respiratory or allergy symptoms, the source
could be within your home. It is easy to take the air you breathe for
granted, but staying informed about these issues will make you aware
of your environment and help you take whatever steps are necessary to
ensure the air around you is safe.
nausea, and fatigue.
Most of the ozone inside our homes
comes from outside. Ozone reacts with
molecules released by air fresheners
and other scented products. The products of these chemical reactions have
similar structures to chemicals known to
be toxic or to cause irritations.
Wood smoke contains very
small particles that cannot
be filtered out by the nose or
the upper respiratory system.
They can remain deep in the
lungs for months before being
cleared. Studies have shown
that these fine particles
increase the risk of heart
attacks and strokes.
If candles are not burning smoothly,
they can give off small particles of
soot that can make their way into
the lungs. Some scented candles
have wicks with a metal core, and a
number of these have been found to
release significant amounts of lead
into the air when they are burned.