Basic Calculations for Occupational Safety and Environmental Health Professionals - Mathematics and Statistics for the Environment - page 394

The bottom line on indoor air quality is the recognition that the outdoor air we breathe is not
always of the same quality as the air we breathe indoors. This recognition that the indoor air
environment is not an exact reflection of outdoor conditions is of relatively recent emergence.
The impact of cigarette smoking, stove and oven operation, and emanations from certain types
of particleboard, cement, and other building materials are often the most significant determi-
nants of indoor air quality. There is a continuing need to characterize human exposures both from
the standpoint of meeting pertinent ambient and occupational standards and the recognition of
potential hazardous levels of pollutants which do not have applicable standards. The implications
of indoor air concentrations for epidemiological studies, where exposures are based on outdoor
measurements, have been recognized and, in the recent past, partially investigated (Dockery and
Spengler, 1981; Spengler, et al., 1979).
So, what exactly is indoor air quality? According to Byrd (2003), indoor air quality refers to the
effect, good or bad, of the contents of the air inside a structure on its occupants. Usually, tempera-
ture (too hot or too cold), humidity (too dry or too damp), and air velocity (draftiness or motionless-
ness) are considered “comfort” rather than indoor air quality issues, unless they are extreme, not
within normal range. They may make someone uncomfortable, but they won't make a person ill.
Nevertheless, most environmental professionals must take these factors into account in investigating
air quality situations. What is good indoor air quality? Simply put, good IAQ is a characteristic of
air that has no unwanted gases or particles in it at concentrations that will adversely affect someone.
Poor IAQ occurs when gases or particles are present at an excessive concentration so as to affect the
satisfaction of health of occupants (Byrd, 2003) . In the workplace, poor IAQ may only be annoying
to one person; however, at the extreme, it could be fatal to all of the occupants in the workplace.
The concentration of the contaminant is crucial. Potentially infectious, toxic, allergenic, or irritating
substances are always present in the air. Note that a threshold level below which no effect occurs is
nearly always a factor.
15.4.1 s ourCes oF i ndoor a ir p ollutants
Air quality is affected by the presence of various types of contaminants in the air. Some are in
the form of gases, and are generally classified as toxic chemicals. Such contaminants can include
combustion products (e.g., carbon monoxide, nitrogen dioxide), volatile organic compounds
(formaldehyde, solvents, perfumes, fragrances), and semivolatile organic compounds (pesticides).
Other pollutants are in particulate form, including various forms of animal dander; soot; particles
from buildings, furnishings, and occupants (e.g., fiberglass, gypsum powder, paper dust, lint from
clothing, carpet fibers); and dirt, among others. Specific sources for contaminants that result in
adverse health effects in the workplace include the workers themselves (e.g., contagious diseases,
allergens and other agents on clothing); building compounds (e.g., VOCs, particles, fibers); con-
tamination of building components (e.g., allergens, microbial agents, pesticides); and outdoor air
(e.g., microorganisms, allergens, chemical air pollutants) (Burge and Hoyer, 1998). When work-
ers complain of IAQ problems, the environmental professional is called upon to determine if the
problem really is an IAQ problem. If it is determined that some form of contaminant is present
in the workplace, proper remedial action is required. This usually includes removing the source
of the contamination.
15.5 AIR POLLUTION FUNDAMENTALS
In the last 40 years, the environmental engineering profession has expanded its responsibilities to
society to include the control of air pollution in the workplace (and homes) but also from industrial
sources that pollute our atmosphere. Though not exactly “seven maids with seven mops trying to
get it clear,” increasing numbers of environmental engineers and practitioners are being confronted
with problems in this most vital area. Although the design and construction of air pollution control