ENGINEERING MANUAL OF AUTOMATIC CONTROL
INDOOR AIR QUALITY FUNDAMENTALS
154
INDOOR AIR QUALITY CONCERNS
bacteria. Gaseous contaminants such as methane are produced
both naturally, by animals and decay, and by man made activity
such as landfills. Location near a fossil fuel power plant, refinery,
chemical production facility, sewage treatment plant, municipal
refuse dump or incinerator, animal feed lot, or other like facility
will have a significant effect on the air introduced into a building.
Below ground sources include radon gas and its by products.
Radon gas is found in all soils in various concentrations. It is a
product of the radioactive decay of radium. Radon, in turn,
generates other radioactive contaminants as it decays. Radon gas
enters buildings primarily through the foundation. Radon can then
decay through a succession of decay products, producing metallic
ions. These products become attached to particulate matter
suspended in the air and can then be inhaled causing health
problems.
Outdoor air pollution is monitored and regulated at the Federal
level by the U.S. Environmental Protection Agency (EPA) which
has set primary and secondary standards for several pollutants
known as criteria pollutants. These criteria pollutants include:
nitrogen dioxide (NO
2
), ozone (O
3
), carbon monoxide (CO), sulfur
oxides, nonmethane hydrocarbons, lead (Pb), and total suspended
particulates (TSP). The EPA estimates that 50 percent of American
cities do not meet all these standards for 1996. See Tables 1 and 2.
Table 1. Annual Median Concentrations for TSP, NO
2
, O
3
, & CO—1979.
a
AIR CONTAMINANTS
Air contaminants are categorized by location and type. Location
of contaminants is divided between outdoor and indoor. Outdoor
air contamination results from natural or manmade phenomena
that occur outdoors or indoors. Contaminant types include
particulate, gas, vapor, radionuclide.
CONTAMINANT SOURCES
Outdoor Contaminant Sources
Outdoor contaminant sources are divided into above ground
and below ground sources. Above ground sources are subdivided
into man made and naturally occurring sources. Man made sources
are those such as electric power generating plants, various modes
of transportation (automobile, bus, train ship, airplane), industrial
processes, mining and smelting, construction, and agriculture.
These contaminants can be loosely classified as dusts, fumes,
mists, smogs, vapors , gases, smokes that are solid particulate
matter (smoke frequently contains liquid particles ), and smokes
that are suspended liquid particulates. Naturally occurring
contaminant sources include pollen, fungus spores, viruses, and
(continued)
Concentration
µg/m
3
mg/m
3
Location TSP (annual average)
b
NO
2
(1 hr average)
O
3
(1 hr average)
CO (1 hr average)
Baltimore 43-102 45 20 1.5
Boston 67 75 — 3.5
Burbank, Ca. — 124 39 3.5
Charleston, WV 43-70 37 14 1.2
Chicago 56-125 63 29 2.9
Cincinnati 47-87 60 24 1.0
Cleveland 58-155 89
c
26 2.0
Dallas 43-73 59
c
39 1.4
Denver 80-194 89 37 4.6
Detroit 52-135 68 14 1.8
Houston 51-147 90
c
39
d
1.0
Indianapolis 48-81 91
c
33 2.7
Los Angeles 90 85 117 2.6
Louisville 60-102 70
c
31 1.5
Milwaukee 47-105 86
c
41 1.4
Minneapolis 45-87 65
c
— 1.8
Nashville 41-82 62
c
49
d
2.6
New York 40-77 57 35 5.5
Philadelphia 51-109 85 39 3.2
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