Indoor Air Pollution Sources
What Causes Problems ?
Three major reasons for poor IAQ in office buildings are
the presence of indoor air pollution sources; poorly designed,
maintained, or operated ventilation systems; and uses of
the building that were unanticipated or poorly planned for
when the building was designed or renovated.
1. Sources of Office Air Pollution
The most important factor influencing IAQ is the presence
of pollutant sources. Commonly found office pollutants and
their sources include environmental tobacco smoke; formaldehyde
from pressed wood products; other organics from building
materials, carpet, and other office furnishings, cleaning
materials and activities, restroom air fresheners, paints,
adhesives, copying machines, and photography and print shops;
biological contaminants from dirty ventilation systems or
water-damaged walls, ceilings, and carpets; and pesticides
from pest management practices.
2. Ventilation Systems
Mechanical ventilation systems in large buildings are designed
and operated not only to heat and cool the air, but also
to draw in and circulate outdoor air. If they are poorly
designed, operated, or maintained, however, ventilation
systems can contribute to IAQ problems in several ways.
For example, problems arise when, in an effort to save energy,
ventilation systems do not bring in adequate amounts of
outdoor air. Inadequate ventilation also occurs if the air
supply and return vents within each room are blocked or
placed in such a way that outdoor air does not actually
reach the breathing zone of building occupants. Improperly
located outdoor air intake vents can also bring in air contaminated
with automobile and truck exhaust, boiler emissions, fumes
from dumpsters, or air vented from restrooms. Finally, ventilation
systems can be a source of indoor pollution themselves by
spreading biological contaminants that have multiplied in
cooling towers, humidifiers, dehumidifiers, air conditioners,
or the inside surfaces of ventilation duct work.
3. Use of the Building
Indoor air pollutants can be circulated from portions of
the building used for specialized purposes, such as restaurants,
print shops, and dry-cleaning stores, into offices in the
same building. Carbon monoxide and other components of automobile
exhaust can be drawn from underground parking garages through
stairwells and elevator shafts into office spaces.
In addition, buildings originally designed for one purpose
may end up being converted to use as office space. If not
properly modified during building renovations, the room
partitions and ventilation system can contribute to IAQ
problems by restricting air recirculation or by providing
an inadequate supply of outdoor air.