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OCR for page 57
TV
SOURCES AND CHARACTERIZATION OF INDOOR POLLUTION
This chapter addresses several chemical pollutants with respect to
their sources, concentrations, and indoor-outdoor relationships. In
addition, with the aim of characterizing the general quality of the
indoor environment, it considers temperature, humidity, unwanted sound,
and electromagnetic radiation, such as the radiofrequency, infrared,
~risible, ultraviolet, and x-ray portions of the spectrum.
In the case of some pollutants, information on health effects is
scanty, at bent. To the extent possible, the health effects of such
pollutants are discussed here. Detailed discussion of the health
effects of other pollutants, on which more information is available, is
to be found in Chapter VII.
Radioactivity and formaldehyde emitted indoors from building
product. are discussed in the first two sections of this chapter.
Consumer products, a generic Source of indoor pollutants of many types,
are discussed next. The chapter proceeds with sections on asbestos and
fibrous glass {which occur in different forms in many indoor
environments), combustion processes (especially of unrented cooking and
heating appliances), and tobacco smoke {a hiahlv complex and ublaultous
mixture of pollutants). Several indoor air pollutants can be
_ . . _ _ , _ _
recognized by their odors. Such odors are often the first indications
of deterioration in air quality and may themselves affect people's
well-being adversely; hence, they are treated as a distinct category of
pollutant in this chapter.
Air temperature, radiant temperature, and
air velocity and humidity affect the quality of the indoor environment
through physiologic and sensory responses, so the thermal environment
is also discussed in a separate section. Other physical factors of the
indoor environment, such as noise and electromagnetic radiation, are
d iscussed briefly in a f inal section.
The diversity of subjects discussed in this chapter is evident.
Some of the pollutants considered here may be associated with ~roluntery
behavioral patterns, such as tobacc~o-amoicing, whereas others may be
related to involuntary and unavoidable exposure, such as exposure to
substances emitted from building materials. me reader should not infer
any order of priority among the pollutants discussed here. An effort
to attach priorities would require judgment" on exposures and effects,
57
OCR for page 58
So
and the order of discussion is not intended to indicate the application
o f such j udgment .
RADIOACTIVITY
INTRODUCTION
Radioactivity and ionizing radiation occur naturally throughout the
biosphere, bath because of the presence of primordial radioactive
elements and their decay products in the earth and because of natural
processes (primarily cosmic radiation) that produce radionuclides or
direct radiation fields. These natural sources expose humans to
radiation both outdoors and in buildings. The magnitudes of various
contributions to total radiation dose vary from place to place and
between outdoors and indoors, and the type of radiation dose depends on
the radiation source. At one extreme, the coemic-radiation field
delivers a dose to the entire body; this dose is not affected greatly
by the presence of a building and may be characterized prissily on the
basis of altitude. At the other extreme, airborne alpha-emitting
radionuclides may deliver doses specifically to the lungs, and their
concentrations indoors may be strongly affected by the nature of
building materials and other sources, such as soil and water, and by
building operations, such as ventilation. As an intermediate case, the
gamma-radiation field arising from radionuclides that are fixed in
place typically exposes the whole body and is affected by radionuclide
concentration, proximity, and shielding. .
In the discussion that follows, we refer to radioactivity
concentrations and radiation fields and, by inference, to radiation
doses from sources that are.inside and outside the body. Radioactivity
is given in curies' 1 Ct - 3.7 x 101° becquerele, so 1 psi ~ 0.037
Bq. Radiation fields can be specified in terms of energy flux' but it
is more conventional in the present context to use units of dose rate,
in which case the type of radiation has to be indicated. We use the
red as the unit of (absorbed) dose when specify5ing q~-radiation
fields (1 red - 0.01 J/kg, so 1 mead ~ 1 x 10~ J/kg). For gamma
doses, the dose in reds is numerically equal to the dose equi~raler~-
(D!:) in rema. A distinction must be drawn between the Tissue dose,.
that actually received by tissue and therefore including self-shielding
by the body, and the fair dose,. that deposited in air in the space
under consideration.
It is useful to atomize the dose-rate contribution in the United
States from radiation arising outside buildings. Three recent
summaries are those of the National Council on Radiation Protection and
asurements34 and the U.N. Scientific Committee on the Effects of
Atomic Radiation,.' which depended heavily on Oakley38 for U.S.
data, and the 1980 BEIR report of the National Research Council. Is
External radiation, that arising from sources outside the body, may be
divided into two categories, cosmic and terrestrial. The average
tissue dose rate outdoors from cosmic radiation is approximately 28
mrads/yr; the dose rate indoor e is slightly reduced by overhead
OCR for page 59
as
shielding (the NCRP report amounted a 10% reduction in average
exposures). This contribution has a substantial altitude dependence,
increasing from about 26 mrads/yr at sea level to about 50 mrads/yr at
1,600 a, the altitude of Denver. The average outdoor population-
weighted tissue dose rate from terrestrial radionuclides--due
principally to gamma rays from potassium-40, the thorium-232 series,
and the uranium-238 series--is approximately 35 mrad~/yr. This dose
rate varies substantially because of geographic variations in the
distribution of these radionuclides. For estimating average
terrestrial dose rates, the NCRP assumed that indoor done rates were
20% lower than outdoor rates. (It also assumed that the tissue dose
was 20% less than the air dose.) Internal radionuclides contribute
important beta and gamma doses (about 15 mrads/yr to cast of the body,
primarily from potassium-40) and an important alpha dose (even if that
to the lungs from radon and its progeny is excluded). The alpha dose
arises primarily from internally deposited uranium-238 and -234,
radium-226 and -228, and polonium-210 and varies greatly with body
organ. One of the larger contributions, about 3 mrads/yr, is the
polonium-210 alpha dose to the cells lining the bone surfaces.
However, alpha particles have a greater biologic effectiveness than
gamma rays, so the absorbed alpha dose contributes a DE some 10 times
greater than that of the same (absorbed) dose of gamma radiation.
Table IV-1 shows estimate. of various contributions to DE rates, in
millirems per year, which are numerically equal to tissue dose rates
(in millirads per year) for gamma and beta radiation. For alpha
radiation, a quality factor of 10 was assumed (based on relative
biologic effectiveness), although 20 is now recommended.' The value
given for lung dose from inhaled radionuclides assumed a radon-222
concentration in air of 0.15 nCi/~3 (and slightly less than
equilibrium amounts of its radioactive decay products, or progeny).
The resulting DE has the largest value in the table. Nonetheless, this
value appears more appropriate for outdoor than for indoor air, in
which higher radon concentrations are found.
All indoor dose rates from natural radiation sources are affected
by buildings, and those from inhaled radionuclides are affected most
strongly. The only natural airborne radionuclides of importance are
radon and its progeny, principally the series beginning with radon-222,
the alpha-decay product of radium-226 (a member of the uranium-238
series). Radon is a noble gas that can move from the site of its
formation, giving it a substantial opportunity to reach air that is
inhaled by humans. The short-lived decay products of radon--polonium,
. . . . . ~ . . . . . _ ~ ~ · _
lead, and b~mutn--are chemically active ana thus can De co~ec~ea An
the lungs, either directly or through particle" to which they attach.
The most important dose arises from alpha decay of the polonium
isotopes. The decay sequence beginning with radium-226 is shown in
Figure IV-1, and, from the biomedical point of view, effectively.ends
with lead-210, because of its half-life of about 20 yr. Because the
alpha energy associated with decays of the short-lived products to
lead-210 poses the main risk, progeny concentrations are often
expressed as the associated potential alpha-energy concentration.
(PAEC) in air. The unit conventionally used for PAEC is the working
OCR for page 60
60
TABLE IV-1
Summary of Average Dose }equivalent Rates from Various Sources
of Natural Background Radiation in the limited Statesa
Bone
Radiation Source Gonads Lung Surfaces Marrow GI Tract
Cosmleb 28 28 28 28 28
Cosmogenic radiormclides 0.7 0. 7
0.8 0.7 0.7
External terrestrials 26 26 26 26 26
Inhaled radionuclideed 1 OOe — — ~
Radionuclides in the bodyf 27 24 60 24 248
Tombs ~ rounded ~ 80 IS0 120 80 80
aReprinted with permission from NCRP.34
blfith 10: reduction for structural shielding.
CWith 20X reduction for shielding by housing and 20X reduction for ahielting
by the body.
d Lung only; doses to other organs included in "Radionuclides in the body.
eLocal DO rate to segmental bronchioles - 450 areme/yr.
fExcluding cos~geni~ contribution.
"Excluding contribution from ra~itomclides in gut contents.
OCR for page 61
61
s~u lull
~SY 1~r
2 "eV
-
Pa '.~lUX,'
1.2 ~
2 3 ~V
'..U lUtIl ~
25Y tO.,
.,'_ 4J - eV
,
' ·'~h ~X,)
24 d
02.01 ~V
"~h Ib}
B0 a 106'
4e _ 47 - V
.
~ ~ 1
1 ~1
r
~JC"
1500 ~
48 - V
sesnn
382d
SS - V
, ·~Po (~) "-o ~'
3.0S~ 16 >< 10~s
60 ~V _7 ~ ~Y
.
t.~s, l—C) ~ '. ,.
19?
04 3.3 - Y
,
"~~ IRaS)' "` tl"
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"~' I~E,'
50d
~1 2 - eV
86 - o l~bF)
138 d
~S 3 - eV
'~ teaG) |
s~ 1
.
FIGllRE: IV-} Principal decay scheme of uranium-238 to radon-222
to lead-206, showing alpha ar~d beta decay; decay energies in
millions of electron volts. Reprinted with permi,'lon {r~om National
Council on Radiation Protection and Measurements. P-
OCR for page 62
62
level (WL), defined as 1.3 x 105 MeV/L, the PANIC if radon-222 at 100
nCi/~3 is present with equilibrium amounts of its progeny. Done (and
DE) rates may be inferred from the PAEC on the basis of relatively
complicated modeling, provided that the progeny particle size
distribution and other factors are prescribed.
The character of a building may affect occupant radiation exposure
in three principal ways: the building serves as a container for
indoor~generated radon and its associated progeny, whether from
building materials, underlying soil, or water and Gas; the building
materials contain natural gamm=-emitters (potassium-40, the thori~232
series, and the uranium-238 series); and the building shields occupants
from cosmic or external terrestrial radiation. The last two effect"
tend to cancel one another. The building structure may, in unusual
circumstances, also protect occupants from outdoor radon-urooenY
. _ ~ _ ~ _ _, _ _ _,
concentrations. However, the indoor concentration 18 ordinarily larger
than the outdoor, and outdoor-generated radon usually contributes a
"mall additive term to indoor concentrations. If this term is ignored,
the steady-state indoor radon concentration for a f iced indoor radon
source strength is inversely proportional to the air-exchange rate, the
rate at which the indoor air is exchanged for outdoor air. The
air-exchange rate for most U.S. buildings is around 1/h, with O.S/h to
1 . 5/h typical for residences (windows closed) . The air-exchange rate
and other removal mechanisms also affect the ratios of radon-progeny
concentration to radon concentration. Lack of removal implies activity
ratios of 1, but substantially lower values have been observed. An
equilibrium factor (F} is often defined as the ratio of the actual Pm3C
to the PAE;C that would be associated with a specific radon
concentration if the progeny were in equilibrium with this
concentration.
This section characterizes indoor airborne radionuclides and
radiation, su~arizes measurements of actual concentrations or
radiation f ields, briefly Indicates con~crol measures, and suggests
subjects for further research. The major emphasis is on radon and its
progeny. The radionuclides in this decay chain, even at typical
outdoor concentrations, cause larger radiation doses to internal organs
than all other airborne radionuclides. Furthermore, the radon and
progeny concentration"may be substantially higher indoor-,
particularly in building with low air-exchange rates. In addition.
building oc`:upants receive external whole-body-radiation from
radionuclides fixed in building materials and soil, and these doses are
also given subetantial treatment. This radiation arises principally
from several primordial radionuclides--potassium-40 and Sobers of the
thorium-232 and uranium-238 decay series--with concentrations of around
0.1 pCi/g or greater in rocks, soil, and derivative building
materials. There are also the decay chains in which radon-220,
radon-222, and their progeny occur.
\
OCR for page 63
63
SC}URCES OF RADICXlilCLIDES AT RADIATION
Building Mater ials
Radionuclide Content. Few measurements and no wide~scale surveys
of the radionuclide content of U.S. building materials have been made.
Surveys of materials in Europe are summarized in UltSCEAR 1977, AMP. 50)
which gives activity concentrations of potassium-40, radium-226, and
thorium-232. As examples, average values for the concrete Ample
groups examined range from 0.9 to 2.0 pCi/g for radium-226, 0.8 to 2.3
pCi/g for thoriu~n-232, and 9 to 19 pCi/g for potassium-40. By
comparison, the ranges for brick are about 50% higher; those for cement
are similar, except for potas~ium-40 (which is SO. less); and those for
natural plaster are lower by about a factor of 5.
Available U.S. data {Table IV-2) show concentrations in the same
range, assuming that the series radionuclides are sufficiently close to
equilibrium to permit comparison. In a number of cares, U.S. workers
have examined the radionuclide contents of concrete in the course of
selec~cing materials for low-background facilities for use in radiation-
counting; 2' the values obtained are consistent with the European
da=, although somewhat lower. The observed concentrations are also
within the range of values typical for major rock types and "oils.
Concentrations for building materials not derived from crustal
components, such as wood, are much lower .
Measurement programs have recently been initiated to characterize
the radionucl~de contents of building mater ials as a basis for
understanding the resulting effect on the indoor radiation
environment. Kahn et al.25 have reported measurements of
concentrations in various building material" in the Atlanta area;
potassi~-40, radium-226 progeny, and thorium-232 progeny
concentrations for samples of concrete, brick, and tile are given in
Table TV-2. Lawrence Berkeley Laboratory has begun to survey concretes
and other materials as part of a program on indoor air quality;
radionuclide contents for concrete and rock-bed samples from a number
of areas are given in the table. I'
Considerably greater radionuclide concentrations may be found in
building materials that contain residues from industrial processed.
The principal example of such materials in the United States in
concrete blocks incorporating phosphate slag Sequentially calcium
silicate), a byproduct of phosphate production. As discussed by
Roessler et al.,.2 this slag contains most of the radium-226 and
uranium~238 found in the phosphate ore. For the electric furnace
Process used in Florida, concentrations in the ore are about 60 pCi/g,
and the slag has similar concentrations. A plane In A'zioame Musing
Florida and Tennessee phosphate ores) sold slag to companies in
Alabama, Mississippi, Tennessee, Georgia, and Kentucky. The concrete
produced by these companies has radium-226 concentrations estimated.
and in some cares measured, to be about 20 pCi/g.25 Phosphogypaum
(essentially calcium sulfate produced by treatment of phosphate ores
with sulfuric acid) may also be used for building materials,
particularly wallboard. In this treatment, radium-226 follows the
OCR for page 64
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OCR for page 65
65
calcium, leading to tens of picocuries per grue in the gypsum but such
gypsum has not been used on ~ large scale in U.S. wallboard. In
contrast, concrete that incorporates phosphate slag may have been used
in approximately 100,000 homes.2S Finally, awe fly ash from
coal-fired power plants has been used in cement production, and tote
use may continue. Heretofore, it has not been thought to contribute
substantially to the radionuclide content of the resulting building
material. IS Bnanation measurements on fly-ash concretes are now
being performed at Lawrence Berkeley Laboratory.
Radon Emanation. The effective radon-222 ser~eration rate in
building ma~ceriale depends on the radi~-226 content, which varies
widely, and on tbe percentage of radon formed that does not rain
lodged in the matrix of the material. Radon that is not fixed in place
may mc've through the matrix by diffusion or, if the material contain e
large air spaces, by convection. Diffusive movement depends on the
diffusion length of the ~nateris1 in question and on its thickness. The
extent to which these processes occur depends not only on the
material ' s characteristics, but also on environmental conditione--
pressure, temperature, and moisture content. A rule of thumb Wartimes
cited {e.g., UNSCEAR.~) is that 1% of the radon-222 generated from
materials in walls and ceilings escapee into the adjacent air space.
However, recent measurements at Lawrence Berkeley "bora~cory and
elsewhere have indicated that a considerably higher fraction can
escape, e.g., from concrete. Ingersoll et al. cited eacape-to-
production ratios of 0.08-0.25 for radon-222 from concrete.
(Radionuclide contents for the sample groups examined are indicated in
Table IV-2. )
Of most direct interest for indoor sir quality is the actual
emanation rate, often given as picocuries per square meter per second
and sometimes as picocuries per gram per second. Measurements for
various materials give emanation rates over a wide range. For exe ~ le.
Euro Ian gypsum board and bricks yield radon-222 at about 0.3 x 10-
pCi/m -a, whereas rates for European concretes range from 0.001 to
0.2 pCi/m2-~.2. 32 Preliminary measurements of radon-222 emanation
rate per unit mast for sample groups of concrete from U.S. metropolitan
areas (Table IV-2) give averages that range from 0.4 to 1.2 pCi/kg-h
(0.8 pCi/lcg-h yields approximately 0.03 pCi/~-s for O.l-~thick
concrete). Several rock samples from solar-beat storage beds averaged
0.5 pCi/kg-h, although radium-226 contents were considerably higher
t ban those for the concrete samples. I' The resulting indoor
radon-222 concentrations depend on the amount of such material in the
structure, the interior volume, and the air~exabange rate. For an
air-exchange rate of lih and a ratio of indoor emanating surface to
indoor volume of 0.5 m~/m3, an emanation rate of 0.03 pCi/m2-e
corresponds to a radon-222 concentration of about 0.04 nCi/m3. If
the equilibrium factor is 0.5, this would yield a PANIC of about 0.0002
WL. Direct measurement of emanation rates of materials made with
industrial byproducts (such ens phosphate-alag concrete is underway.
but results are not available. Because these materials may contain 20
times a. much radion-226 as a typical concrete, radon-222 contributions
OCR for page 66
66
of up to several nanocuries per cubic - ter of radon-222 and a
corresponding increase in the PANIC could be expected if the same
emanation ratio pertains.
Measurements of emanation rate vary by more than an order of
magnitude, I' no it is difficult to use radium content to predict the
contribution of a particular material to indoor radon content. For
this reason, more comprehensive information on diffusible fraction,
diffusion length, etc., and their dependence on material or
environmental factors is required before we can characterize building
materials on the basis of radionuclide content. If this information
becomes available, radionuclide Contents may then be helpful in
characterizing indoor concentrations on a broad scale, e.g., by
geographic area. Ilowever, the dependence of diffusion and emanation
r ates on environmental factors, such as pressure and temperature, and
on the Moisture content of the material may limit the possibility for
such characterization.
In some cases, radon-220 (.thoron.) and its progeny, ordinarily
present at much lower concentrations than radon-222 and its progeny,
may assume importance, particularly when mechanisms exist for
transporting emanating radon-220 rapidly into the air space of
interest. In comparison with the half-life of radon-222, the much
shorter half-life of thoron, 55 s, caches the measured radioactivity in
curies to be a characteristic of secondary interest. However, the PAEC
still gives a relatively direct indication of possible dose to the
lung. One WL of radon-222 progeny has the same PAEC as that associated
with progeny in eguilibrium with thoron at 7 nCi/~3. To the extent
that uranium-238 and thorium-232, which have similar half-lives, have
similar activities In source materials, the PAEC from their progeny,
radon-220 and -222, can reach similar values if rapid transport
mechanisms exist. This may occur, for example, in solar buildings that
sweep air through rock or concrete thermal-atorage beds. A few efforts
have begun to measure thoron emanation rates, but results are not yet
available.
Gamma Radiation. The energies and intensities of photons f rom
decay of natural radionuclide. have been well characterized. The
external dose from radionuclides in building materials is due to the
gamma rays emitted and depends on the geometry of the structure and
attenuation by the materials, as well as the gaama-ray energies. A
simple expression may be derived for the -ray air dose in a hole
in an infinite uniform medium:25
X',,, ~ (2.43 Vrad/h) (1i;UCU + EThcq~h + EKCK} .
where Cu. CTh, and CR are the concentrations (in picocuries per
g ram) of uraniu~238 and it's progeny, thor lum-232 and its progeny, and
potassium-40, respectively, and Eu, ETh, and E': are the average
ga~a-ray energies per disintegration of the same radionuclides
(including disintegration of the progeny for the uranium and thorium
-eeriest. Used Eu ~ 1.72 Mev, E',h ~ 2.36 MeV, and ER a 0.156
MeV, 25 t" ~ 4 ECU + 5.7CTh + 0.38CR, in microrads per
OCR for page 67
67
hour. The stated dose contributions from the uranium and thorium
series are slightly less than those cited elsewhere. e.g., by Krisiuk
et al., 27 who may have used older information on decay schemes. For
the radionuclide contents cited in Table IV-2, the three terms in the
expression for to contribute comparable amount". (An analogous
expression for the dose from a flat plane is cited in the section on
soil. ~
For an actual structure, the geometry is complex and Salaried; in
addition, the building materials may attenuate the external radiation
dose from other sources. Moreover, radon-222 and its progeny may be
present in the material at less ton equilibrium values, thereby
decreasing the corresponding gamoa-ray dose. The radon-222
escape-to~production ratio is most often in the range of low to 0.25,
causing a small reduction in the value of X. The effects of geometry
and attenuation cannot be so simply characterized. Dose-rate
expressions from various workers, pertaining to a variety of
structures, have been summarized.3' Some of these expressions
account for reduction of the dose rate from outdoor sources. Moeller
_ al.' described a computer program suitable for analysis of varied
geometries.
The infinite-geometry case yields air dose rates of about 8
wads/in for a potassiumr40 concentration of 8 pCi/g and uranium-238
and thorium-232 series concentrations of 0.5 pCi/g. An infinitely
thick slab of such material would contribute about half thin dose rate
at its surface. As discussed earlier, ~ typical outdoor tissue dose
rate from terrestrial radionuclides is 35 mrads/yr or 4 prads/h.
{Owing to shielding by the body, the tissue dose rate is about 20% less
than the air dose rate.}
Soil and Groundwater
Radionuclide Content. Radionuclide concentrations of major rock
types and soil have been summarized.'. U.S. soil values of 0.6, 1.0,
and 12 pCi/g have been stated for uraniu~-238, thorium-232. and
potasstum-40, respectively, on the basis of 200 measurements of
g~mm^-ray dose rate cited by Lowder et al.'° These values vary by a
factor of around 3 from place to place. Values for crustal rocks'.
typically lie within this Dame range, but are considerably higher for
some formations. For example, the phosphate rocks of Florida contain
the uranium-238 Series at tens of picocuries per gram, but normal
amounts of thoriu~-232s commercial uranium ore bodies in the United
States have uranium-238 concentrations of hundreds of picocur ies per
gram and higher.
Radon Emanation and Transport. The uranium-238 series, typically
presenS in soils and rocks at concentrations of about 1 pCi/g, includes
radium-226, the source of radon-222. The actual radon-222 emanation
rate from the ground depends, as for building materiels, on the
percentage of diffusible radon, diffusion length, and other transport
mechanisms (including groundwater) in the soil. A review of available
OCR for page 214
214
infrared, visible light, ultraviolet, and x-ray portions of the
electromagnetic spectrum. The freguencies of the electromagnetic
radiation discussed here range from 104 Ez {radiofrequency) to 1015
Hz {ultraviolet). Table IV-24 s''mn~rizes the frequency distribution
for each of these portions of the spectrum and of audible sound, which
is transmitted via the vibration of air molecules.
SOUND AND NOISE
Phvaical Character i8tiC8
The audibility of sound depends on intensity and frequency, with a
maximal human response in the region near 3 x 103 Ez. A sound with
predominant frequencies below 100 Hz or above 104 Hz may require ~
million times more energy to have the same audibility as a sound with a
predominant frequency of 3 x 103 Ez. A method of weighting the
pressure exerted by the sound waves at different frequencies has been
developed to compensate for these variations. The decibel values
(which constitute a logarithmic intensity scale) cited herein are
measurements with level A weighting, the scale that most closely
matches the response of the human ear. The difference. in the
treatment of the intensity content of a sound are alight and do not
change substantially from one source to another."'
Sounds in the indoor environment are generated both outside and
inside the occupied space. Table IV-25 gives examples of sound
intensities in the outdoor environment. Table Iv-26 lists sound
intent ities produced by typical household appliances in the indoor
environment.
Sound intensities are usually measured by a meter satisfying the
requirements of American National Standards Institute Specification
SI.4-1971 {for sound meters).
PsYchoPhysiolosic Effects
The possible effects of sound include permanent and temporary 108S
of hearing, cardiovascular disease, sleep disruption, and paychologic
effects. :. The physiologic and psyabologic responses to sound may be
transitory; ~. however, there i'; insufficient information on the
effects of sound by itself or in combination with other stressore.
Sound at intensities that are found to be objectionable will affect
productivity and decrease enjoyment of the environment. ~.
'~e EPA has identified sound intensities that, if not exceeded,
should protect against some of the adverse effects of sound. ~. These
values are expressed in term of maximal 8-h
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TABLE IV-24
Radiation Wavelengthe and Frequencies
Type of Radia~cion Wave length Frequency, Hz
Ultraviolet
Ultraviolet C 0.19~0.28 vm 1.07 x 1014-1.58 x 10~5
Ultraviolet B 0.28-0.315 um 9.5 s 1014-1.07 s 124
Ultraviolet A 0.315-0.4 ym 7.5 s 101 -9.5 s 10
Visible light 0.4-0.7 llm 4 29 s 1ol4_7 5 x 1ol4
Infrared 4 14
Near infrared 0.7-1.4 um 2.14 x 101 -4.29 ~c 10
Infrared 1.4-3 pm 1.00 ~c 1011-2.14 ~c 10 4
Far infrared 3-1,000 um 3 x 101 -1.00 ~c 10}
Radio frequency ~ 1 1
Microwave 1-1,000 ~ 3 x 1O7-3 x 10
Ves~y high frequency 1-10 m 3 x 10 -3 x 10
High frequency 10-100 m 3 ~c 10 -3 ~ 10
Medium frequency 100~1, 000 m 3 x 1O4-3 x lO5
Low frequency 1,000~10,000 m 3 x 10 -3 x 10
Very low frequency 10,000-30,000 m 1 x 10 -3 x 10
Sount, audible 0.016-20.0 o~ 15-2 x 104
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TABLE IV-2 5
Examples of Outdoor Day-Night Average Sound Intensities
at Various Locations a
Location
Apartment next to freeway
Downtown with some construction
Urban high-dens ity apartment
Urban row housing on major avenue
Old urban residential area
Wooded res idential area
Agricultural cropland
Rural residenelal area
Wil de rnes s ambient
aData from Council on Enviror~ental Quali~cy. 4
TABLE IV-2 6
Average Sound
Intensity, dB(A)
88
79
78
68
59
51
44
39
35
Examples 0 f Sound Intensities Generated Indoors
by Household Appliancesa
Appl lance
Blende r
Garbage disposer
Window air conditioner
Re f rigerator
Vacuum cleaner
Hair dryer
Mixe r
aData fray Jones e 8
Average Sound
Intensity, dB (A)
80-90
80
60
45
70-75
78
82
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considered safe. However, above 110 do, sound is so intense that most
people experience pain or a tickle in their ears. ~.
Although it is difficult to determine the exact day and night
indoor sound intensities, studies have indicated that an intensity of
6 0 . 4 dB with a s tandard deviation of 5 . 9 dB can be expected in a
typical urban residential area, with instantaneous intensities
exceeding 80 dB. 12 An exacted intensity of 60.4 do is below the 70
dB recommended by the EPA to prevent hearing loss, but it is well above
the intensity recommended to aneroid interference and annoyance.
Therefore, day and night sound intensities in the 100-site EPA survey
may contribute to speech interference, reduced worker productivity, and
annoyance.iotpp. 66-69)
A high intensity of background noise in urban areas stemming
primarily from transportation appears to affect the developing fetus.
Women exposed to aircraft noise have a higher proportion of
low-birthweight children, who are at higher risk of mortality and both
physical and mental effects.~°(PP 110-111) This association
cannot be separated from the social status of the women (a
codetermining variable), inasmuch as many members of the lower social
classes live in Noisy areas.
Exposure to high intensities of sound affects communication and
learning, including the acquisition of language.~°(P 115)
Adaptation or resignation to annoyance may occur, and there do not
appear to be groups of people that are particularly sensitive.
After-effects of noise have been noted at home and at work, and noise
appears to influence aggressiveness and minimize voluntary helping
behavior.~otPp. 120-12
RADIOFREQUENCY AND MICROWAVE RADIATION (104 to 3 x 1011 HZ
.
Phys ical Character istics
Although the physical characteristics of all electromagnetic
radiation are similar, the frequency is inversely proportional to
wavelength, and the effects of the longer wavelengths, such as
radiofrequency radiation, are radically different from those of the
shorter-wavelength ioniz ing radiation, such as x rays and gamma rays .
The photon energy in radio waves is so small that there is no
ionization when it is absorbed in an organism. Is
Table IV-27 summarizes the radiation properties of some common
nonionizing-radiation systems and their expected far-field power
densities. Energy radiated by these systems can be additive, provided
that the frequencies are within the same octave band.
For the purposes of this report, the densities of all radio-
frequency energies generated outdoors are defined as Background power
densities, ~ and those of radiofrequencies generated indoors as
Generated power densities..
Some radiofrequency energy is generated in the indoor environment.
In general, all electric equipment produces come radiofrequency
radiation. However, all but a few electric devices radiate energy at
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218
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219
well below the American National Standards Institute recommended
exposure limits, even in combination with one another. One ma jor
exception is the microwave oven. Under normal operating conditions, a
residential microwave oven radiates approximately 1 mW/cm2 at the
Real on the door. However, If the door is defective, values in excess
of 1 W/cm2 can be achieved.
PsYchophYs ioloq ic Ef f eats
Effects of radiofrequency radiation can be divided into two major
categories: t~ thermal effects (when the radio-wave energy is
converted into heat) and nonthermal effects (which cannot be directly
explained by thermal equivalents).
Biologic effects depend on the f requency and the intensity of the
radiation; the duration of exposure; the dielectric constant,
temperature, and thermal conductivity of the irradiated tissue; the
ability of the tissue to dissipate heat; and the dimensions of the
body. Absorption of microwave radiation by body tissues results in an
increase in temperature, often producing internal burns due to local
hot spots caused by nonuniformity in the f ield. The eyes and testes
were found to be the most sensitive. I'
Specific effects at the cellular or molecular level were postulated
more than a decade ago without resolution of the importance of these
effects with respect to biologic damage. 3 The possibilities of
nonthermal effects, such as rearrangements within macromolecules and
subcellular structures, have been under investigation for many years,
but further studies will be necessary to clarify the issues. It Is
relatively clear that metabolic and functional disturbances at the
cellular level can be caused by microwave radiation, but the mechanisms
of these ef fects are not yet well understood.
Table IV-28 characterizes the relative rates of absorption by the
human body; however, it is difficult to determine the exact effect of
each frequency. Because the radiofrequency energy generated indoors is
low, the ma jor emphasis should be on outdoor sources. Indoor
radiofrequency f ields are generally lower than outdoor. Osepchuck has
discussed sources of microwave and other forms of radiofrequency
energy .
FAR-~NF~D AND INF=~D =DIATION {3 x 1011 HZ to 4 .3 x 1014 HZ
Physical Character istics
.
The infrared energy spectrum ranges from far-infrared (3 x 10
Hz to 1014 Hz), through infrared (1.0-2.14 x loll Hz), to near-
infrared (2.14-4.29 x 1014 Hz). Infrared radiation is produced
naturally by the sun and by all common heating and artificial-light
sources. The incandescent lamp is one of the major sources of infrared
radiation and the most common artificzal-light source in the indoor
environment. Of the total input wattage of an incandescent lamp,
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TABLE IV-28
Relative Absorption of Radiofrequencies by Hen Bodya
Frequency, 106 Hz
<400
400-1, 000
1,000~3,000
3, 000~10, 000
Haximn1 Absorption
by Human Body,
<50
50~100
20-100
>50
aData from U. S. Department of Health, Education, and Welf are . 13
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75-808 is converted to near-infrared and infrared radiation.' The
ACGIE has adopted ~ TLV of 10 mW/ce2 for infrared radiation in the
workplace. The power density 2 ~ from ~ 100-W lamp is approximately
0.6 mW/cm2 for the total infrared spectrum. Sunlight on the earth's
surface produces a flux of about 70 mW/cm2, of which about half is
infrared.
Psychophvaiologic Effects
Depending on its wavelength, infrared is absorbed in the surface of
the skin (wavelengths larger than 2 ye) or can penetrate asveral
millimeters (waveleng the between O.7 and 1.5 And. Safety standards
in industrial environments are based on the risk that infrared
radiation may induce cataracts in the eyes of persons exposed to
excessive infrared radiation, such as glassblowers or open-hearth
steelworkers.~.
Excessive infrared radiation is most easily controlled by shielding
the source with reflecting metallic foils.
VISIBLE RADIATION
Physical Character tStiC8
Radiation in the near-infrared and visible spectrum is produced by
many sources, both natural and artificial. Our sense of sight, feeling
of well-being, and comfort are all. to a great extent, influenced by
Risible and near-infrared radiation.
Psychophysiologic Effects
Retinal burns from observation of the sun have been described
throughout history. Chorioretin-1 burns rarely occur from exposure to
artificial light, because the normal aversion to high-brightnese light
sources (the blink reflex) provide. adequate protection , unless the
exposure is hazardous within the duration of the blink reflex.
Many factors at feet the usefulness of visible light . Among the
most important are discomfort glare and disability glare. Light
sources can cause ~ reduction in contrast of an image, owing to
scattered visible radiation, by adding a uniform veil of luminance to
the object. This effect, commonly called .veiling luminance,. may
cause a reduction in visual performance without physical damage.
Discomfort glare is a sensation of annoyance or pain caused by
brightness in the field of view that is greater than that to which the
eyes are adapted. It has been shown that the threshold of discomfort
glare changes as ~ function of age.2 Although discomfort glare does
not necessarily interfere with visual performance, it can cause eye
strain and contribute to fatigue. Disability glare and ocular stray
light influence one's ability to perform a task by artificially veiling
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the contrast of the visual target. It is therefore a great contributor
to eye fatigue.
ULTRAVIOLET RADIATION (0 . 75-1. S8 x 1015 Ez;
-
wavelength, 0. 19-0.400 =)
Physical Characterstics
Ultraviolet radiation is divided into three wavelength categories:
ultraviolet-A (W-A), 0 . 315-0 .400 - ; ultraviolet-B (W-B),
0.28-0.315 - ; and ultraviolets (W~C}, 0.19-0.28 - . All
fluorescent lamps emit W-A, but not W-B or ARC. High-inten~ity
d ischarge lamps produce W-A, W-B, and some ARC. Incandescent lamps
produce small amounts of W-A, and essentially no W-B and ARC.
Ultraviolet radiation is measured with specialized radiometric
photome ters .
Psychophysiologic Ef feats
UV-B and W~C are known photocarcinogens. s Doses of W-B and
W~C 10 times the human minimal erythema dose (MET)) have initiated
squamous cell carcinomas, and chronic continuous exposure to W-A can
also have a carcinogenic effect. s
The ACGIH recommends limits on workplace ultraviolet exposure that
depend on wavelength and on the duration of exposure.' For W-A, the
intensity should not exceed 1 mW/cm for more than 1,000 a, nor
s hould the dose exceed 1 J/cm2 i f g iven in less than 1, 000 s . For
W-B and Wee, the dose should not exceed about 3-10 =/cra2 in any
8-h period. The degree of hazard seems to be associated with the
erythemal efficiency of each frequency. ~ s
SUMMARY
Ionizing and nonionizing electromagnetic radiation occurs in the
indoor environment. This radiation can be harmful, and one cannot
always sense its presence.
Sound can generally be heard and in some cases felt. Excessive
sound can cause deterioration of hearing acuity and, if extremely
intense or prolonged, cause deafness. Background sound in the urban
residential environment can exceed the recommended intensities and
result in interference and annoyance. Sound of 70-80 do, commonly
found in indoor environments, can inhibit task performance and possibly
contribute to aggressive human behavior. ~
Infrared, far-infrared, and radiofrequency radiation produce no
visible or audible evidence of their presence. However, infrared
radiation does provide sensory indication of its presence by heating of
human tissue. Far-infrared and radiofrequency radiation, however,
provide no indication of their presence, unless their power levels are
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so high as to increase skin temperature. Heating of human tissue
occurs because of the infrared output of incandescent lamps. However,
the detrimental effects of this heating have not been fully
investigated. Surveys have shown that in several cities 98% of the
people are exposed to less than 1 ~W/cm2 from broadcasting
transmitters.' However, ultrahigh-frequency television transmitters
can radiate radiofrequency pollution to adjacent buildings at 5-200
W/cm2 .
Ultraviolet-A, visible light, and near-infrared radiation can
produce surface heating of human and animal tissue. These frequencies
are of concern because of their ability to affect human performance.
The veiling reflections caused by most artificial lighting systems can
have substantial influence on human visual performance. Reduction of
veiling reflections can increase visual performance and decrease the
energy consumed by lighting systems. Transient adaptation (dilation
during or immediately after eye movements) i. caused by sudden changes
in the visual spectrum power. Transient adaptation contributes to eye
fatigue and decreased visual performance.
REFERENCES
7.
1. American Conference of Governmental Industrial Hygienists. ILUs.
Threshold Limit Valuen for Chemical Substances in Workroom Air
Adopted by ACGIH for 1980 . Cincinnati: Amer ican Conference of
Governmental Industrial Hygienists, 1980. 93 pp.
2. Bennet, H. J. Discomfort Glare: Demographic variables, p. 6. IER]
Special Report No. 118, 1976.
3. Cleary, E. Biological Effects and Health Implications of Microwave
Radiation. Symposium Proceedings. Richmond, Virginia, September
17-19, 1969. U. S. Department of Health, Education, and Welfare,
Bureau of Radiological Health Publication No. BRH/DBE 70-2.
Washington, D.C.: U.S. Government Printing Office, 1971. 265 pp.
4. Council on Environmental Quality. Noise, pp. 533-576 . In
Environmental Quality--1979. The Tenth Annual Report of the Council
on Environmental Quality. Washington, D.C.: U.S. Government
Printing Office, 1980.
5. Cunningham-Dunlop, S., and B. H. Kleinstein. Wavelength dependence,
pp. 51-61. In Carcinogenic Properties of Ionizing and Nonionizing
Radiation. Vol. I. Optical Radiation. DREW (NIOSH) Publication No.
78-122. Washington, D.C.: U.S. Government Printing Office, 1977.
Geen, R. G., and E. C. O'Neal. Activation of the cue-elicited
aggression by general arousal. J. Pers. Soc. Psychol. 11:289-292,
1969.
Janes, D. E., Jr. Radiation surveys--Measurement of leakage
emissions and potential exposure fields. Bull. N.Y. Acad. Med.
55:1021-1041, 1979.
8. Jones, H. W. Noise in the Human Environment. Edmonton, Alberta:
Environmental Council of Alberta, 1979.
9. Kaufman, J. E., and J. F. Christensen, Eds. IES Lighting Handbook.
The Standard Lighting Guide. 5th ed. New York: Illuminating
Engineering Society, 1972.
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1U. National Research Council, committee on Apprales1 ot Societe1
Consequences of Transportation Noise Abatement. Noise Abatement:
Policy Alternatives for Transportation. Wanton, D.C.: National
Academy of Sciences, 1977. 206 pp.
osepobuck, J. M. Sources and bB8tC characteristics of microwave/RF
radiation. Bull. N.Y. Acad. Ned. 55:976-998, 1979.
Schultz, T. J. Noise Assessment Guidelines. (Technical Background
for Norse Abatement In BUD's Operating Programs.) U.S. Department
of Housing and Urban Development Report No. TE/NA 172. Washington,
D.C.: U.S. Government Printing Office, 1971. 210 pp.
13. Salty, S. W., and D. G. Brown. Radio Frequency and Radio HIcrowave
Radiation Levels Resulting from Mhn-Made Sources in the Washington,
D.C. Area, pp. 1-13. U.S. Department of Bealtn, Education, and
Welfare Pub. No. (FDA)72-8015. Washington, D.C.: U.S. Government
Printing O$tice, 197Z.
14. U.S. Environmental Protection Agency, Ot$lce of Nolse Abatement and
Control. Tnformatzon on Levels of Environmental Noise Red taite to
Protect Public Health and Weltare With an Adequate Margin of
Safety. O.S. Environmental Protection Agency Report No.
550/9-74-004. Washington, D.C.: U.S. Government Printing Office,
1974. tZ141 pp.
15. Vogelman, J. H. Physical characteristics of microwave and other
rad~ofrequency radiation, pp. 7-10. In S. F. Cleary, Ed. Biological
Effects and Health Implication. of Microwave Radiation. Symposium
Proceedings. Richmond, virgins, September 17-19, 1969. U.S.
Department of Health, Education, and Weltare, Bureau of
Radiological Bealth Publication No. BRE/DBE 70-2. Washington, D.C.:
U.S. Government Printing Office, 1971.
16. Wallace, J., P. M. Sweetnam, C. G. Warner, P. A. Graham, And A. L.
cocbraner An ep~demtological study of lens opacities among steel
workers. Br. J. Ind. Mea. 28:265-Z71, 1971.
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Geneva: World Health Organization, 1972. 387 pp.
Representative terms from entire chapter:
indoor air
