The document discusses occupational exposure limits (OELs) for chemicals in the workplace, highlighting that the exact number of chemicals in use is unknown, but thousands are regulated. OELs are guidelines set by various organizations to ensure worker safety by indicating maximum allowable concentrations of harmful substances, with different organizations using different terminologies. The document also describes U.S. regulations such as permissible exposure limits (PELs) and their inadequacies, as well as European and other international exposure limits.

1. Occupational Exposure
Limits (OEL)
Ahmed-Refat AG Refat
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2. How many chemicals are in use
today?
• No one, not even the Environmental
Protection Agency (EPA), knows how many
chemicals are in use today.
• EPA has more than 85,000 chemicals listed on
its inventory of substances that fall under the
Toxic Substances Control Act (TSCA).
• https://cen.acs.org/articles/95/i9/chemicals-
use-today.html
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3. • CAS substance collection,
CAS REGISTRYSM contains :
• 144 million organic and inorganic
substances disclosed in literature since
the early 1800s .
• 67 million protein and
nucleic acid sequences
• Updated daily
• https://www.cas.org/about/cas-content
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4. OELs
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5. Occupational Exposure Limit (OEL)
• In general, the occupational
exposure limit (OEL) represents
the maximum airborne
concentration of a toxic
substance to which a worker can
be exposed over a period of time
without suffering any harmful
consequences.
https://www.ccohs.ca/oshanswers/hsprograms/occ_hygiene/occ_exposure_limits.html
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6. Occupational Exposure Limit (OEL)
• These limits are set out by many
professional organizations around
the world.
• They are established based on the
chemical properties of the
substance, experimental studies on
animals and humans, toxicological
and epidemiological data.
https://www.ccohs.ca/oshanswers/hsprograms/occ_hygiene/occ_exposure_limits.htm
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7. Occupational Exposure Limit (OEL)
• Different organizations may use different
terminology for the OEL.
• For example, the ACGIH term for OEL is
"Threshold Limit Value" (TLV)® while the
NIOSH term is "recommended exposure
limits" (REL).
• The OELs developed by the professional
organizations are guidelines. Only the values
adopted and prescribed by the legislation are
enforceable.
https://www.ccohs.ca/oshanswers/hsprograms/occ_hygiene/occ_exposure_limits.html
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8. What are TWA, PEL and REL?
1.USA
OSHA
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9. https://www.osha.gov/
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10. OSHA’s mandatory PELs in the Z-Tables
https://www.osha.gov/dsg/annotated-pels/index.html
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11. Facts About PELshttps://www.osha.gov/chemicalmanagement
• PELs, are regulations that establish
the acceptable concentration of a
substance in the air in the workplace.
• PELs are intended to protect workers
from adverse health effects .
• Of the thousands of chemicals used in
workplaces, OSHA has PELs for about
500.
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12. Facts About PELshttps://www.osha.gov/chemicalmanagement
• Many of the PELs have not been updated since
1971
• The outdated PELs are not sufficiently protective
of worker health.
• In 1989, OSHA attempted to update or set new
PELS for more than 350 chemicals in a single
rulemaking……………………. The entire rulemaking
was ultimately removed by the Court.
• Since 1971, OSHA has been successful in
establishing or updating PELs for only about 30
chemicals.
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13. Other occupational exposure limits
(OELs)
• It shall be noted that other occupational
exposure limits (OELs) are also used in the
United States. They shall be included in SDSs if
available.
• OSHA Permissible Exposure Limits (PELs)
• California OSHA Permissible Exposure Limits
(PELs)
• NIOSH Recommended Exposure Limits (RELs)
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14. Layout of the Z Tables of OSHA
ACGIH
TLVs
NIOSH
RELsCalifornia
OSHA
PEL
OSHA
PELs
https://www.osha.gov/dsg/annotated-pels/tablez-1.html
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15. Limit variations ( CO as example)
50 ppm OSHA 35 ppm Ca/OSHA
25 ppm ACGIH ????????????????
Carbon
monoxide
630-08-0 50 55 25 ppm
(C) 200 ppm
35 ppm
(C) 200 ppm
25 ppm
Substance CAS No.(c)
Regulatory Limits
OSHA
Recommended
Limits
OSHA PEL(b)
Cal/OSHA PEL(f)
(as of
4/4/2018)
NIOSH
REL(g)
(as of 7/7/16)
ACGIH®
2018
TLV® (h)
ppm(d) mg/m3(e)
8-hour TWA
(ST) STEL
(C) Ceiling
Up to 10-hour
TWA
(ST) STEL
(C) Ceiling
8-hour TWA
(ST) STEL
(C) Ceiling
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16. What are TWA, PEL and REL?
1.USA
NOISH
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17. NIOSH NPG
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18. NIOSH Pocket Guide to Chemical
Hazards (NPG)
• The “NPG” gives general industrial hygiene
information for hundreds of chemicals/classes.
• The NPG presents key data for chemicals .
• NIOSH offers four versions of the NPG:
– print,
– online,
– PDF, and
– mobile web app.
https://www.cdc.gov/niosh/npg/default.html
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19. What are TWA, PEL and REL?
1.USA
ACGIH
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20. https://www.acgih.org/
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21. • Threshold Limit Value
(TLV®) occupational
exposure guidelines are
recommended for more
than 700 chemical
substances and physical
agents.
• There are more than 50
Biological Exposure Indices
(BEIs®) that cover more
than 80 chemical
substances
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22. TLVs & BEIs
• Threshold Limit Values (TLVs®)
• Biological Exposure Indices
(BEIs®) are determinations
made by a voluntary body of
independent knowledgeable
individuals.
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23. TLVs & BEIs
• TLVs of the ACGIH represent the
opinion of the scientific community
that has reviewed the data described
in the Documentation, that exposure
at or below the level of the TLV® or
BEI® does not create an unreasonable
risk of disease or injury.
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24. TLVs & BEIs
• TLVs® and BEIs® are not standards.
• They are guidelines designed for use
by industrial hygienists in making
decisions regarding safe levels of
exposure to various chemical
substances and physical agents found
in the workplace.
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25. TLVs & BEIs
• TLVs® and BEIs® are health-
based values established by
committees that review
existing published and peer-
reviewed literature in various
scientific disciplines
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26. TLVs® and BEIs®
are based solely on health
factors,
there is no consideration
given to economic or
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27. What are TWA, PEL and REL?
2.EC
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28. ‫األوزوبي‬ ‫اإلتحبد‬
•‫توجٌهات‬ ‫أربعة‬ ً‫األوروب‬ ‫اإلتحاد‬ ‫أصدر‬Directives
(‫عام‬ ‫من‬1991ً‫حت‬2009)‫التعرضات‬ ‫قٌم‬ ً‫عل‬ ‫شملت‬
ً‫اجمال‬ ‫لعدد‬ ‫بها‬ ‫الموصى‬ ‫المهنٌة‬123‫كٌماوٌة‬ ‫مادة‬.
•‫بها‬ ‫الموصى‬ ‫القٌم‬ ‫وسمٌت‬«ً‫المهن‬ ‫التعرض‬ ‫حدود‬OELs
ً‫االوروب‬ ‫لالتحاد‬-EU Community Occupational
Exposure Limits (OELs)»
‫بها‬ ‫الخاصة‬ ‫الوطنٌة‬ ‫القٌم‬ ‫تضع‬ ‫بؤن‬ ‫باالتحاد‬ ‫دولة‬ ‫لكل‬ ‫الحرٌة‬ ‫ترك‬ ‫مع‬
ً‫المهن‬ ‫التعرض‬ ‫لحدود‬.
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29. In Europe ( EU-OELs )
• In Europe, there are two types of occupational
exposure limits for chemical agents:
1. EU community exposure limits (set by the
European Agency for Safety and Health at
Work)
2. National exposure limits (taking into account
the Community values. National exposure
limit values may be different from the
community values)
https://www.chemsafetypro.com/Topics/EU/EU_Occupational_Exposure_Limits_(OELs).htmlwww.slideshare.net/ahmedrefat 29

30. EU Occupational Exposure Limits
(OELs)
• https://www.chemsafetypro.com/Topics/EU/EU_Occupational_Exposure_Limits_(OELs).html
• https://www.chemsafetypro.com/type?action=main&id=4
DIRECTIVE 2009/161/EC •19 chemical substances;
DIRECTIVE 2006/15/EC •33 chemical substances;
DIRECTIVE 2000/39/EC •61 chemical substances;
DIRECTIVE 91/322/EEC •10 chemical substances;
The EU Community Occupational Exposure Limits (OELs)
are specified in various directives and are updated
regularly.
The table below summarizes the update history of EU
community OELs. ( Total - 123 Substances )
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31. • COMMISSION DIRECTIVE
2000/39/EC
• of 8 June 2000
• establishing a first list of
indicative occupational
exposure limit values in
implementation of Council
Directive 98/24/EC on the
protection of the health and
safety of workers from the
risks related to chemical
agents at work
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32. ‫االتحبد‬ ‫تىجيهبث‬ ‫حسب‬ ‫بهب‬ ‫انمىصي‬ ‫انقيم‬ ‫نجدول‬ ‫مثبل‬
‫االوزوبي‬
Einecs (1) CAS (2) Name of
agent
Limit values Notati
onEight hours Short-term
mg/m3 ppm mg/m3 ppm
200-467-2 60-29-7 Diethylether 308 100 616 200 —
200-662-2 67-64-1 Acetone 1 210 500 — — —
200-663-8 67-66-3 Chloroform 10 2 — — Skin
200-756-3 71-55-6 1,1,1-
Trichloroethane
555 100 1 110 200 —
INDICATIVE OCCUPATIONAL EXPOSURE LIMIT VALUES
(1) Einecs: European inventory of existing chemical substances.
(2) CAS: Chemical abstract service registry number.www.slideshare.net/ahmedrefat 32

33. What are TWA, PEL and REL?
3.Egypt
‫البٌئة‬ ‫وزارة‬
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34. ‫انبيئت‬ ‫قبوىن‬
‫زقم‬ ‫قبوىن‬4‫نسىت‬1994
‫بإصداز‬‫زقم‬ ‫ببنقبوىن‬ ‫وانمعدل‬ ‫انبيئت‬ ‫شأن‬ ‫في‬ ‫قبوىن‬9‫نسىت‬2009
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35. ‫انبيئت‬ ‫نقبوىن‬ ‫انتىفيريت‬ ‫انالئحت‬
‫قرار‬
‫رقم‬ ‫الوزراء‬ ‫مجلس‬ ‫رئٌس‬338‫لسنة‬1995
‫البٌئة‬ ‫لقانون‬ ‫التنفٌذٌة‬ ‫الالئحة‬ ‫بإصدار‬
‫رقم‬ ‫بالقانون‬ ‫الصادر‬4‫لسنة‬1994
http://www.egyptera.org/Downloads/Laws/a-enviroment_law.pdf
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36. ‫انتىفيريت‬ ‫انالئحت‬ ‫مالحق‬‫نهقبوىن‬
•-1‫لبعض‬ ‫والمواصفات‬ ‫المعاٌٌر‬‫فى‬ ‫تصرٌفها‬ ‫عند‬ ‫المواد‬‫البٌئة‬‫البحرٌة‬.
•-2‫تخضع‬ ‫التى‬ ‫المنشآت‬‫البٌئى‬ ‫للتقٌٌم‬.
•-3‫نموذج‬‫سجل‬‫البٌئة‬ ‫على‬ ‫المنشؤة‬ ‫نشاط‬ ‫تؤثٌر‬(‫البٌئٌة‬ ‫الحالة‬ ‫سجل‬)
•-4ً‫الط‬‫إمساكها‬ ‫أو‬ ‫قتلها‬ ‫أو‬ ‫صٌدها‬ ‫المحظور‬ ‫البرٌة‬ ‫والحٌوانات‬ ‫ور‬.
•-5‫لملوثات‬ ‫القصوى‬ ‫الحدود‬‫الخارجى‬ ‫الهواء‬
•-6‫فى‬ ‫الهواء‬ ‫لملوثات‬ ‫بها‬ ‫المسموح‬ ‫الحدود‬‫اإلنبعاثات‬
•-7‫بها‬ ‫المسموح‬ ‫الحدود‬‫الصوت‬ ‫لشدة‬‫له‬ ‫اآلمن‬ ‫العرض‬ ‫ومدة‬.
•-8‫الهواء‬ ‫لملوثات‬ ‫القصوى‬ ‫الحدود‬‫أماكن‬ ‫داخل‬
‫العمل‬‫كل‬ ‫لنوعٌة‬ ‫وفقا‬‫صناعة‬.
•-9‫درجتى‬ ‫من‬ ‫لكل‬ ‫األدنى‬ ‫والحد‬ ‫األقصى‬ ‫الحد‬‫والرطوبة‬ ‫الحرارة‬‫ومدة‬
‫لها‬ ‫التعرض‬‫الوقاٌة‬ ‫ووسائل‬‫منها‬.
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37. ‫زقم‬ ‫انمهحق‬(8)
‫كم‬ ‫نىىعيت‬ ‫وفقب‬ ‫انعمم‬ ‫أمبكه‬ ‫داخم‬ ‫انهىاء‬ ‫نمهىثبث‬ ‫انقصىي‬ ‫انحدود‬‫صىبعت‬
‫عمودٌن‬ ً‫عل‬ ‫الجدول‬ ‫ٌحتوي‬
•‫االول‬ ‫العمود‬:‫المادة‬ ‫اسم‬(ً‫لحوال‬ ‫سرد‬280‫مادة‬)
•ً‫الثان‬ ‫العمود‬:‫قٌم‬‫العتبٌة‬ ‫الحدود‬‫أعمدة‬ ‫ثالث‬ ‫إلى‬ ‫تقسٌمه‬ ‫وتم‬
‫فرعٌة‬:
•ً‫الجزئ‬ ‫المتوسط‬
•‫قصٌرة‬ ‫لفترة‬ ‫التعرض‬ ‫حدود‬
•‫مالحظات‬(‫الجلد‬ ‫و‬ ً‫السقف‬ ‫الحد‬ ‫بها‬ ‫وضع‬)
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38. ‫زقم‬ ‫انمهحق‬(8)
‫كم‬ ‫نىىعيت‬ ‫وفقب‬ ‫انعمم‬ ‫أمبكه‬ ‫داخم‬ ‫انهىاء‬ ‫نمهىثبث‬ ‫انقصىي‬ ‫انحدود‬‫صىبعت‬
‫العتبٌة‬ ‫الحدود‬
‫الحدود‬‫التى‬ ‫الهواء‬ ‫فى‬ ‫الكٌمٌائٌة‬ ‫المواد‬ ‫تركٌزات‬ ‫هى‬ ‫العتبٌة‬
‫حدوث‬ ‫دون‬ ‫ٌوم‬ ‫بعد‬ ‫ٌوما‬ ‫العاملون‬ ‫لها‬ ‫ٌتعرض‬ ‫أن‬ ‫ٌمكن‬
‫أنواع‬ ‫ثالث‬ ‫إلى‬ ‫وتنقسم‬ ‫صحٌة‬ ‫أضرار‬:
.1‫الحدود‬‫العتبٌة‬-8‫ساعات‬.
.2‫الحدود‬‫العتبٌة‬–15‫دقٌقة‬.
.3‫الحد‬‫السقفى‬
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39. ‫العتبٌة‬ ‫الحدود‬
•1.‫الحدود‬‫العتبٌة‬-‫المتوسط‬‫الزمنى‬:‫وهى‬‫لٌوم‬ ‫الزمنى‬ ‫المتوسط‬
‫عادى‬ ‫عمل‬(8‫ساعات‬)‫العامل‬ ‫لها‬ ‫ٌتعرض‬ ‫أن‬ ‫ٌمكن‬ ‫والتى‬5‫أٌام‬‫فى‬
‫األسبوع‬‫صحٌة‬ ‫أضرار‬ ‫حدوث‬ ‫دون‬ ‫عمله‬ ‫فترة‬ ‫طوال‬.
•2.‫العتبٌة‬ ‫الحدود‬-‫قصٌرة‬ ‫لفترة‬ ‫التعرض‬ ‫حدود‬(‫العتبٌة‬ ‫الحدود‬
15‫دقٌقة‬)‫تركٌز‬‫الملوث‬‫بإستمرار‬ ‫العاملون‬ ‫لها‬ ‫ٌتعرض‬ ‫أن‬ ‫ٌمكن‬ ‫التى‬
‫قصٌرة‬ ‫لفترة‬.‫مدة‬15‫فترة‬ ‫خالل‬ ‫حال‬ ‫بؤى‬ ‫تجاوزها‬ ‫ٌجوز‬ ‫ال‬ ‫والتى‬ ‫دقٌقة‬
‫من‬ ‫أكثر‬ ‫ذلك‬ ‫ٌتكرر‬ ‫أن‬ ‫وال‬ ‫العمل‬4‫أن‬ ‫وٌجب‬ ‫الواحد‬ ‫الٌوم‬ ‫فى‬ ‫مرات‬
‫ٌلٌه‬ ‫والذى‬ ‫قصٌر‬ ‫تعرض‬ ‫كل‬ ‫بٌن‬ ‫الفترة‬ ‫تكون‬60‫األقل‬ ‫على‬ ‫دقٌقة‬.
•3.‫ا‬‫السقفى‬ ‫لحد‬:‫هو‬‫الذي‬ ‫الحد‬‫وعندما‬ ‫للحظة‬ ‫ولو‬ ‫تجاوزه‬ ‫ٌجوز‬ ‫ال‬
‫توضع‬ ‫التعرض‬ ‫زٌادة‬ ً‫ف‬ ‫عامال‬ ‫الجلد‬ ‫طرٌق‬ ‫عن‬ ‫االمتصاص‬ ‫ٌكون‬‫إشارة‬
(+‫جلد‬)‫العتبى‬ ‫الحد‬ ‫أمام‬.
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40. ‫زقم‬ ‫انمهحق‬ ‫مكىوبث‬8
: :‫يهي‬ ‫مب‬ ‫انيه‬ ‫مضبفب‬ ً‫انسئيس‬ ‫انجدول‬
•‫للتعرض‬ ‫العتبٌة‬ ‫الحدود‬‫لآلتربة‬‫المعدنٌة‬(‫معادالت‬ ‫و‬ ‫سرد‬)
•‫العتبٌة‬ ‫الحدود‬‫المضاٌقة‬ ‫تسبب‬ ‫التى‬ ‫لؤلتربة‬‫فقط‬(‫سرد‬)
•‫العتبٌة‬ ‫الحدود‬‫المسرطنة‬ ‫للمواد‬‫والتى‬‫أنها‬ ‫فى‬ ‫ٌشتبه‬
‫مسرطنة‬(‫جدول‬-27‫مادة‬)
•‫مواد‬‫عتبٌة‬ ‫حدود‬ ‫لها‬ ‫ولٌس‬ ‫سرطانى‬ ‫تأثٌر‬ ‫ذات‬‫ال‬ ‫معروفة‬
‫أو‬ ‫بمالمستها‬ ‫للعاملٌن‬ ‫ٌسمح‬‫بأى‬ ‫له‬ ‫التعرض‬‫طرٌقة‬(‫سرد‬)
•‫مواد‬‫صناعٌة‬ ‫عملٌات‬ ‫أو‬‫مسرطنة‬ ‫أنها‬ ً‫ف‬ ‫ٌشتبه‬(‫سرد‬)
•‫ا‬‫لتهوٌة‬‫أماكن‬ ً‫ف‬‫العمل‬
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41. ‫زقم‬ ‫نهمهحق‬ ً‫انسئيس‬ ‫انجدول‬ ‫عسض‬ ‫طسيقت‬8
‫حىاني‬ ‫به‬280‫كيمبويت‬ ‫مبدة‬
12
3
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42. What are TWA, PEL and REL?
3.Egypt
‫العاملة‬ ‫القوى‬ ‫وزارة‬
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43. ‫انعمم‬ ‫قبوىن‬
‫ا‬‫بالجرٌدة‬ ‫المنشور‬
‫الرسمٌة‬‫العدد‬14‫مكرر‬‫بتارٌخ‬7/4/2003
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44. ‫انعمم‬ ‫قبوىن‬
‫ا‬‫لمادة‬213‫من‬‫رقم‬ ‫العمل‬ ‫قانون‬12‫لسنة‬2003
‫بالجرٌدة‬ ‫المنشور‬‫الرسمٌة‬‫العدد‬14‫مكرر‬‫بتارٌخ‬7/4/2003
•ً‫عل‬ ‫ٌنص‬
•‫األمان‬ ‫حدود‬ ‫ببٌان‬ ‫قرارا‬ ‫المختص‬ ‫الوزٌر‬ ‫ٌصدر‬
‫المبٌنة‬ ‫المخاطر‬ ‫لدرء‬ ‫الالزمة‬ ‫واالحتٌاطات‬ ‫واالشتراطات‬
‫بالمواد‬(208،209،210،211،212)‫القانون‬ ‫هذا‬ ‫من‬
‫المعنٌة‬ ‫الجهات‬ ‫رأي‬ ‫أخذ‬ ‫بعد‬ ‫وذلك‬.
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45. ‫زقم‬ ‫قساز‬211‫نسىت‬2003
•‫والهجرة‬ ‫العاملة‬ ‫القوى‬ ‫وزارة‬
‫رقم‬ ‫قرار‬211‫لسنة‬2003
‫لدرء‬ ‫الالزمة‬ ‫واالحتٌاطات‬ ‫واالشتراطات‬ ‫األمان‬ ‫حدود‬ ‫شأن‬ ً‫ف‬
‫الفٌزٌائٌة‬ ‫المخاطر‬
‫بٌئة‬ ‫وتأمٌن‬ ‫والسلبٌة‬ ‫والكٌمٌائٌة‬ ‫والبٌولوجٌة‬ ‫والمٌكانٌكٌة‬
‫العمل‬
•ً‫ف‬ ‫منشور‬
‫المصرٌة‬ ‫الوقائع‬-‫العدد‬277(‫ب‬ ‫تابع‬)ً‫ف‬5-10-2003
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46. ‫انجدول‬(15)
‫انعمم‬ ‫بيئت‬ ‫في‬ ‫انتعسضبث‬ ‫و‬ ‫نهمهىثبث‬ ‫انعتبيت‬ ‫انحدود‬
‫الصفحة‬ ‫من‬80‫الي‬183
‫انجدول‬ ‫نشكم‬ ‫ومىذج‬(‫االول‬ ‫انجزء‬-ً‫أون‬ ‫صفحت‬)
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47. ‫انجدول‬(15)
‫انعمم‬ ‫بيئت‬ ‫في‬ ‫انتعسضبث‬ ‫و‬ ‫نهمهىثبث‬ ‫انعتبيت‬ ‫انحدود‬
‫الصفحة‬ ‫من‬80‫الي‬183
‫انجدول‬ ‫نشكم‬ ‫ومىذج‬(‫انجزء‬‫انثبوي‬:‫صفحت‬‫ثبويت‬)
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48. ‫بجدول‬‫انعتبيت‬ ‫انحدود‬‫تىجد‬645‫مبدة‬
‫انمهىثبث‬ ‫مه‬‫و‬‫انتعسضبث‬
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49. Remember!
A legal limit or guideline
(OEL) should never be
viewed as a line
between "safe" and
"unsafe".
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50. Remember!
The best approach is to always keep exposures or the
risk of a hazard as low as possible.
• As an example, carcinogens are not usually defined
by an exposure limit. With many carcinogens, it is
difficult to say for certainty that if exposure is below
a set point, the agent is not likely to cause harm. For
this reason, for carcinogens and other specific agents
(such as allergens), the "As Low as Reasonably
Practicable" (ALARA) principle should be applied.
ALARA, in practical terms, means that exposure
should be eliminated or reduced as much as
possible.
https://www.ccohs.ca/oshanswers/hsprograms/occ_hygiene/occ_exposure_limits.html
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51. Adopted limits are not sufficiently
protective of worker health
• Industrial experience, new developments in
technology, and scientific data clearly indicate
that in many instances these adopted limits
are not sufficiently protective of worker
health.
• Many large industrial organizations have felt
obligated to supplement the existing OSHA
PELs with their own internal corporate
guidelines.
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52. Adopted limits are not sufficiently
protective of worker health
• OSHA’s Hazard Communication standard
(1910. 1200 Appendix D) requires that safety
data sheets list not only the relevant OSHA
PEL but also the ACGIH® TLV® and any other
exposure limit used or recommended by the
chemical manufacturer, importer, or employer
preparing the safety data sheet.
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53. Adopted (PELs) of OSHA are not
sufficient to protective worker’s health
• To provide employers, workers, and other
interested parties with a list of alternate
occupational exposure limits that may serve to
better protect workers, OSHA has annotated
the existing Z-Tables with other selected
occupational exposure limits. OSHA has
chosen to present a side-by-side table with
the Cal/OSHA PELs, the NIOSH Recommended
Exposure Limits (RELs) and the ACGIH® TLVs®s.
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