what is the occupational exposure limit?
Airborne concentrations of a biological, chemical, or physical agent that almost every worker is believed to be exposed to without experiencing any harmful effects. A small percentage of workers may experience discomfort or even suffer a work-related illness from exposure to concentrations or levels below the limit value.
The purpose of WELs that worker not exposed to a high concentration of an airborne substance, does not matter short duration or long duration of a period.
The exposure is calculated by measuring a worker exposed period to harmful substance are known as time-Weighted Average.
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time-Weighted Average |
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Short-Term Exposure Limit (STEL) |
15 Minutes |
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Long-Term Exposure Limit (LTEL) |
8 Hours |
STEL (short-term exposure
limit) that presents a short-term exposure value as the maximum concentration
in air of a chemical, biological or physical agent to which workers can be exposed, provided that the exposure is no more than 15
minutes and occurs no more than four times in a workday.
LTEL (Long Term Exposure Limit)
is presented as an exposure time-weighted average (TWA) value, which is the
time-weighted average concentration or levels of a chemical or
biological agent for an 8-hour
shift. or a 40-hour week to which it is believed that almost all workers can be exposed day after day, without suffering
harmful effects.
WHAT IS THE DIFFERENCE BETWEEN A PEL, TLV, weel AND REL?
The permissible exposure limit (PEL)
PELs are
established by the Occupational Safety and Health Administration (OSHA). PELs are exposure limits to hazardous
substances 8-hour period referenced in CFR 29 1910.1000.
Threshold Limit Value (TLV)
TLV is established by the American Conference of
Governmental Industrial Hygienists (ACGIH). TLV is not a regulatory requirement
but a recommended guideline. TLVs are exposure limits to hazardous
substance 8-hour period.
Workplace Environmental Exposure Limit (WEEL)
WEEL is established by the American Industrial
Hygiene Association (AIHA). WEEL is not a regulatory requirement but a
recommended guideline. WEELs are exposure limits to hazardous substance 8-hour
period.
Recommended Exposure Limit (REL)
REL are established by the National Institute
for Occupational Safety and Health (NIOSH). REL is not a regulatory
requirement, but a recommended guideline to exposure limits to hazardous
substances 8-hour period (40-hour workweek).
Other health risks by a specific agent in the workplace,
Asbestos: asbestos causes lung cancer, mesothelioma,
asbestosis and pleural plaques.
Bloodborne virus: bloodborne are hepatitis and
human immunodeficiency virus (HIV – the agent of Acquired Immune
Deficiency Syndrome (AIDS)). Coronavirus, Hepatitis B and C are great risks in the workplace.
Carbon Monoxide: colourless, odourless poisonous
gas
Bacteria: Legionella Bacteria cause “Legionnaires” the disease also called Legionellosis. Leptospira Bactria carriers of the disease Leptospirosis.
Silica: hazardous by inhalation causes Silicosis,
very similar to Asbestosis
Wood dust: hazardous by inhalation causes Asthma
Cement: irritant and corrosive causes dermatitis on skin contact and burn eye contact.
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Exposure to hazardous substances can be prevented by approach to the general hierarchy of control.
Elimination – eliminate
the process, or type of work,
Substitution – use
fewer hazards substance,
Exposure time reduction – reduce exposure time, establish job rotation,
Use of respiratory protection – use a respirator to avoid dust, fumes, vapours, mist inhalation
such as half mask, full face mask, breathing apparatus (BA - breathing air
supply from cylinders of air on a trolly, connected to a hose to facepiece),
Self-contained breathing apparatus (SCBA – pressurized small cylinder carry by the user on his/her back)
Use of personal protective equipment – PPE
- Hand protection: use
safety glove to protect from chemical, biological, physical hazards)
- Ear protection: use
safety goggle, face shield to protect from splashing, flying hazards.
- Body protection: fire resistance clothing (FRC), The chemical-resistant suit protects from chemical, biological, splashing, fire
hazards,
Personal hygiene:
personal hygiene is useful to protect against chemical ingestion. Hand washing before
eating, touching the nose or mouth can save cross-contaminated by hand contact.
Health surveillance: provision of health surveillance for those exposed to hazardous a substance to detection of ill health.
Instruction, information, training and supervision
