EVERY MINUTE, YOU TAKE ABOUT 16 BREATHS. THAT MEANS YOU TAKE MORE THAN 8 MILLION BREATHS EVERY YEAR. With each
inhalation, everything suspended in the air
enters your lungs. In urban areas, vehicle
exhaust, smoke from power plants and factories, and other chemicals can make this air
a toxic brew. But once you make it into the
climate-controlled air-conditioned comfort of
the great indoors, is the air safe from all these
dirty chemicals? Not really.
In most cases, it is not the outside air getting in, but rather pollutants that originate from
within the structure itself (Fig. 1). Because
many homes and buildings are poorly ventilated, the concentration of toxic gases and airborne irritants can build up to dangerous levels.
So what are these indoor air pollutants, and
what are their harmful effects to human health?
Radon is the perfect example of a silent killer. If you
look to the far right and bottom corner of the periodic
table, you will find radon, the heaviest noble gas (atomic
mass number of 222). It is one of the densest gases
known. Radon is colorless and odorless. But according to
the U.S. Environmental Protection Agency, radon causes
20,000 lung cancer deaths each year in the United States.
It is the second leading cause of lung cancer in the United
States. You can find some radon in every home, but if the
level is abnormally high, it should be cause for concern.
Radon occurs in many isotopic forms. Radon-222 is
the most common form in the environment, and it is a
member of the radioactive decay chain of uranium-238.
Uranium is commonly found in rocks and
soil, especially those with high concentrations of granite. Like all radioactive elements, uranium’s nucleus is
unstable and decays to other nuclei, emitting high-energy
particles or rays. The highly energetic particles and rays
can do substantial chemical damage to living organisms—if their concentration inside these organisms is
Because radon is dense, it tends to travel horizontally
through the soil, accumulating in the basement. It can
enter the basement through cracks or other gaps in the
foundation. It can also enter through the water supply.
Close-Up Look at the
Quality of Indoor Air
By Brian Rohrig