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Equivalent sound level contours.
TABLE 1-Continued Octave band sound pressure levels
PERMISSIBLE NOISE EXPOSURES may be converted to the equivalent A
Sound level weighted sound level by plotting them Duration per
dBA slow day, hours
response on this graph and noting the A
100 weighted sound level corresponding to
102 the point of highest penetration into 1 .........
105 the sound level contours. This equiva
110 44 or less..........
115 lent A-weighted sound level, which
'When the daily noise exposure is composed of two or more perimay differ from the actual A-weighted
ods of noise exposure of different levels, their combined effect sound level of the noise, is used to de should be considered, rather than the individual effect of each. If the termine exposure limits from Table I.
sum of the following fractions: CI/TI+C2/T2 * * * Cn/Tn exceeds unity, then, the mixed exposure should be considered to exceed the
limit value. Cn indicates the total time of exposure at a specified sound exceeding those listed in Table I noise level, and Tn indicates the total time of exposure permitted at
that level. of this section, feasible administrative or engineering controls shall be uti
Exposure to impulsive or impact lized. If such controls fail to reduce
noise should not exceed 140 dB peak sound levels within the levels of the
sound pressure level. table, personal protective equipment (34 FR 7946, May 20, 1969, as amended at 35 shall be provided and used to reduce FR 1015, Jan. 24, 1970) sound levels within the levels of the
Subpart C-Radiation Standards table.
(c) If the variations in noise level in $ 50-204.20 Radiation-definitions. volve maxima at intervals of 1 second . As used in this subpart: or less, it is to be considered continu: (a) “Radiation" includes alpha rays, ous.
beta rays, gamma rays, X-rays, neu(d) In all cases where the sound trons, high-speed electrons, high-speed levels exceed the values shown herein, protons, and other atomic particles; a continuing, effective hearing conser- but such term does not include sound vation program shall be administered. or radio waves, or visible light, or inTABLE I
frared or ultraviolet light.
(b) “Radioactive material” means PERMISSIBLE NOISE EXPOSURES'
any material which emits, by sponta
Sound level Duration per
neous nuclear disintegration, corpusday, hours
response cular or electromagnetic emanations. 8 ...................
(C) "Restricted area” means any area 6 ..........
access to which is controlled by the employer for purposes of protection of
individuals from exposure to radiation tion to estimate with reasonable accuor radioactive materials.
racy the approximate distribution in (d) “Unrestricted area" means any energy of the neutrons, the incident area access to which is not controlled number of neutrons per square centiby the employer for purposes of pro- meter equivalent to 1 rem may be estitection of individuals from exposure to mated from the following table: radiation or radioactive materials.
NEUTRON FLUX DOSE EQUIVALENTS (e) “Dose" means the quantity of ionizing radiation absorbed, per unit of mass, by the body or by any portion
Number of Average flux to of the body. When the provisions in
deliver 100 Neutron energy
millirem in this subpart specify a dose during a
(million electron centimeter
40 hours period of time, the dose is the total volts (Mev]) equivalent to a (neutrons/cm quantity of radiation absorbed, per
dose of 1 rem
(neutrons/cm2 unit of mass, by the body or by any portion of the body during such period
970 X 106
670 of time. Several different units of dose
720 X 106 are in current use. Definitions of units
820 X 106
570 used in this subpart are set forth in 0.02.
400 X 106
120 X 106 paragraphs (f) and (g) of this section.
43 X 106 (f) “Rad” means a measure of the
26 X 106 dose of any ionizing radiation to body 2.5.........
29 X 106
5.0........ tissues in terms of the energy ab
26 X 106 7.5.
24 X 106 sorbed per unit of mass of the tissue.
24 X 106 One rad is the dose corresponding to 10 to 30.
14 x 106 the absorption of 100 ergs per gram of tissue (1 millirad (mrad)=0.001 rad).
(h) For determining exposures to X(g) “Rem” means a measure of the
or gamma rays up to 3 Mev., the dose dose of any ionizing radiation to body
limits specified in this part may be astissue in terms of its estimated biologi
sumed to be equivalent to the “air cal effect relative to a dose of 1 roent
dose”. For the purpose of this subpart gen (r) of X-rays (1 millirem
"air dose” means that the dose is (mrem)=0.001 rem). The relation of
measured by a properly calibrated apthe rem to other dose units depends
propriate instrument in air at or near upon the biological effect under con
the body surface in the region of the sideration and upon the conditions for
highest dosage rate. irradiation. Each of the following is considered to be equivalent to a dose $ 50–204.21 Exposure of individuals to raof 1 rem:
diation in restricted areas. (1) A dose of 1 rad due to X- or
(a) Except as provided in paragraph gamma radiation;
(b) of this section, no employer shall (2) A dose of i rad due to X.,
possess, use, or transfer sources of iongamma, or beta radiation;
izing radiation in such a manner as to (3) A dose of 0.1 rad due to neutrons
cause any individual in a restricted or high energy protons;
area to receive in any period of one (4) A dose of 0.05 rad due to particles
calendar quarter from sources in the heavier than protons and with suffi
employer's possession or control a dose cient energy to reach the lens of the
in excess of the limits specified in the eye;
following table: (5) If it is more convenient to measure the neutron flux, or equivalent,
calendar than to determine the neutron dose in
quarter rads, as provided in paragraph (g)(3)
1. Whole body: Head and trunk; active bloodof this section, 1 rem of neutron radi
forming organs; lens of eyes; or gonads....
144 ation may, for purposes of the provi. 2. Hands and forearms; feet and ankles .........
1874 sions in this subpart be assumed to be
3. Skin of whole body ..........
7% equivalent to 14 million neutrons per (b) An employer may permit an indisquare centimeter incident upon the vidual in a restricted area to receive body; or, if there is sufficient informa- doses to the whole body greater than
those permitted under paragraph (a) days not falling within a complete calof this section, so long as:
endar week of that year, such days (1) During any calendar quarter the shall be included within the last comdose to the whole body shall not plete calendar week of the previous exceed 3 rems; and
year; or (2) The dose to the whole body, (3) The four periods in a calendar when added to the accumulated occu- year may consist of the first 14 compational dose to the whole body, shall plete, consecutive calendar weeks; the not exceed 5 (N-18) rems, where "N" next 12 complete, consecutive calendar equals the individual's age in years at weeks, the next 14 complete, consecuhis last birthday; and
tive calendar weeks, and the last 12 (3) The employer maintains ade complete, consecutive calendar weeks. quate past and current exposure rec. If at the end of a calendar year there ords which show that the addition of are any days not falling within a comsuch a dose will not cause the individ- plete calendar week of that year, such ual to exceed the amount authorized days shall be included (for purposes of in this paragraph. As used in this this part) within the last complete calparagraph “Dose to the whole body” endar week of the year. If at the beshall be deemed to include any dose to ginning of any calendar year there are the whole body, gonad, active blood days not falling within a complete calforming organs, head and trunk, or endar week of that year, such days lens of the eye.
shall be included (for purposes of this (c) No employer shall permit any part) within the last complete week of employee who is under 18 years of age the previous year. to receive in any period of one calen (e) No employer shall change the dar quarter a dose in excess of 10 per method used by him to determine calcent of the limits specified in the table endar quarters except at the beginin paragraph (a) of this section.
ning of a calendar year. (d) “Calendar quarter" means any 3month period determined as follows:
$ 50–204.22 Exposure to airborne radioac(1) The first period of any year may
tive material. begin on any date in January: Pro (a) No employer shall possess, use or vided, That the second, third, and transport radioactive material in such fourth periods accordingly begin on a manner as to cause any employee, the same date in April, July, and Octo within a restricted area, to be exposed ber, respectively, and that the fourth to airborne radioactive material in an period extends into January of the average concentration in excess of the succeeding year, if necessary to com- limits specified in Table I of Appendix plete a 3-month quarter. During the B to 10 CFR Part 20. The limits given first year of use of this method of de- in Table I are for exposure to the contermination, the first period for that centrations specified for 40 hours in year shall also include any additional any workweek of 7 consecutive days. days in January preceding the starting In any such period where the number date for the first period; or
of hours of exposure is less than 40, (2) The first period in a calendar the limits specified in the table may be year of 13 complete, consecutive calen increased proportionately. In any such dar weeks; the second period in a cal period where the number of hours of endar year of 13 complete, consecutive exposure is greater than 40, the limits calendar weeks; the third period in a specified in the table shall be decalendar year of 13 complete, consecu- creased proportionately. tive calendar weeks; the fourth period (b) No employer shall possess, use, in a calendar year of 13 complete, con or transfer radioactive material in secutive calendar weeks. If at the end such a manner as to cause any individof a calendar year there are any days ual within a restricted area, who is not falling within a complete calendar under 18 years of age to be exposed to week of that year, such days shall be airborne radioactive material in an included within the last complete cal. average concentration in excess of the endar week of that year. If at the be- limits specified in Table II of Appenginning of any calendar year there are dix B to 10 CFR Part 20. For purposes
of this paragraph, concentrations may there exists radiation at such levels be averaged over periods not greater that a major portion of the body could than 1 week.
receive in any one hour a dose in (C) “Exposed” as used in this section excess of 5 millirem, or in any 5 conmeans that the individual is present in secutive days a dose in excess of 100 an airborne concentration. No allow millirem; and ance shall be made for the use of pro (3) "High radiation area" means any tective clothing or equipment, or parti area, accessible to personnel, in which cle size, except as authorized by the there exists radiation at such levels Director, Bureau of Labor Standards. that a major portion of the body could
receive in any one hour a dose in 8 50-204.23 Precautionary procedures and
excess of 100 millirem. personnel monitoring. (a) Every employer shall make such 8
$ 50–204.24 Caution signs, labels, and sig. surveys as may be necessary for him to comply with the provisions in this sub- (a) General. (1) Symbols prescribed part. “Survey” means an evaluation of by this section shall use the conventhe radiation hazards incident to the tional radiation caution colors (magen. production, use, release, disposal, or ta or purple on yellow background). presence of radioactive materials or
The symbol prescribed by this section other sources of radiation under a spe is the conventional three-bladed cific set of conditions. When appropri- design: ate, such evaluation includes a physical survey of the location of materials
RADIATION SYMBOL and equipment, and measurements of 1. Cross-hatched area is to be magenlevels of radiation or concentrations of ta or purple. radioactive material present.
2. Background is to be yellow. (b) Every employer shall supply appropriate personnel monitoring equipment, such as film badges, pocket chambers, pocket dosimeters, or film rings, to, and shall require the use of such equipment by:
(1) Each employee who enters a restricted area under such circumstances that he receives, or is likely to receive, a dose in any calendar quarter in excess of 25 percent of the applicable value specified in paragraph (a) of $ 50-204.21; and
(2) Each employee under 18 years of age who enters a restricted area under such circumstances that he receives, or is likely to receive, a dose in any calendar quarter in excess of 5 percent of the applicable value specified in paragraph (a) of $ 50-204.21; and
(3) Each employee who enters a high radiation area.
(c) As used in this subpart:
(1) "Personnel monitoring equipment” means devices designed to be worn or carried by an individual for the purpose of measuring the dose re (2) In addition to the contents of ceived (e.g., film badges, pocket cham signs and labels prescribed in this secbers, pocket dosimeters, film rings, tion, employers may provide on or etc.);
near such signs and labels any addi(2) “Radiation area” means any tional information which may be aparea, accessible to personnel, in which propriate in aiding individuals to mini
(2) Each area or room in which natural uranium or thorium is used or stored in an amount exceeding 100 times the quantity specified in Appendix C to 10 CFR Part 20 shall be conspicuously posted with a sign or signs bearing the radiation caution symbol and the words:
HIGH RADIATION AREA (2) Each high radiation area shall be equipped with a control device which shall either cause the level of radiation to be reduced below that at which an individual might receive a dose of 100 millirems in 1 hour upon entry into the area or shall energize a conspicuous visible or audible alarm signal in such a manner that the individual entering and the employer or a supervisor of the activity are made aware of the entry. In the case of a high radiation area established for a period of 30 days or less, such control device is not required.
(d) Airborne radioactivity area. (1) As used in the provisions of this sub part, “airborne radioactivity area” means (i) any room, enclosure, or operating area in which airborne radioactive materials, composed wholly or partly of radioactive material, exist in concentrations in excess of the amounts specified in column 1 of Table 1 of Appendix B to 10 CFR Part 20 or (ii) any room, enclosure, or operating area in which airborne radioactive materials exist in concentrations which, averaged over the number of hours in any week during which individuals are in the area, exceed 25 percent of the amounts specified in column 1 of the described Table 1.
(2) Each airborne radioactivity area shall be conspicuously posted with a sign or signs bearing the radiation caution symbol and the words:
(f) Containers. (1) Each container in which is transported, stored, or used a quantity of any radioactive material (other than natural uranium or thorium) greater than the quantity of such material specified in Appendix C to 10 CFR Part 20 shall bear a durable, clearly visible label bearing the radiation caution symbol and the words:
(2) Each container in which natural uranium or thorium is transported, stored, or used in a quantity greater than 10 times the quantity specified in Appendix C to 10 CFR Part 20 shall bear a durable, clearly visible label bearing the radiation caution symbol and the words: