TOPIC 3 : CHEMICAL HAZARD ASSESSMENT AND PROTECTION
Outline of topic 3:
WORK PLACE AND PERSONAL MONITORING
EXPOSURE TO HAZARDOUS CHEMICALS IN LABORATORIES
PERSONAL PROTECTIVE EQUIPMENTS
EYE, FACE,HEAD,FOOT, HAND AND RESPIRATORY PROTECTION
CHEMICAL PROTECTING CLOTHING
WHAT IS YOUR UNDERSTANDING?
• Who are you ?
• What is your role?
• We have any ISSUES for these?
• Are you important for this ISSUES…….?
WHAT IS CHEMICAL HAZARD?
Chemical Hazard is the danger caused by chemicals to the environment and people.
A chemical hazard arises from contamination with harmful or potentially harmful chemicals.
Acetronitrile, Acids,Asbestos,Beryllium,Cadmium,Cyanide compounds,
Hydrogen Fluoride,Lead,Lithium compounds,Mercury,Methylene Chloride,
Extent to which a person may be safely exposed to a hazardous substance (typically a
gas or solvent vapor) without endangering his or her health. These limits are generally
discretionary and every country defines its own limits, resulting in a lack of widely
According to the circumstance of the exposure can be :
• Accidental: Unintentional and unexpected exposure. This
includes food poisoning.
• Intentional: Exposure with the intention of causing harm.
This includes suicide attempts, suicides, and homicides.
• Occupational: Exposure during the industrial processes of
manufacture, storage, transportation, application, and final
• Continuously (for short term)
- control strategy where the risk is high
• Intermittently (for long term)
- initial determination of hazard
- spot measurement in an established process
- routine check measurement
• harmful characteristics of the substance, energy or
• concentration, intensity or level of the exposure to
the harmful agent
• time duration of the exposure
• Elimination-most effective means of hazards control (involves
physical removal of hazards)
• Substitution- second effective way to control hazards (removing
something that produces hazards and replacing with something
that does not produce a hazard)
• Engineering control- third effective controlling hazards (not
eliminate hazards, but rather keep people isolated from hazards)
• Administrative control – changes to the way of people work (do
not remove hazards, but prevent people exposure to the hazards)
• Personal protective equipment – least effective way to control
hazards ( due to high potential of PPE to become ineffective due
• designed to control the absorption of airborne
contaminants into the body
• measured in:
- ppm (parts of vapour/gas per million parts of air)
- mg/m3 (milligrams of substance per cubic metre of
• expressed as the concentration of an airborne
substance averaged over a reference period
-15 minutes short term limit
- 8 hours long term limit
OCCUPATIONAL EXPOSURE LIMITS
Maximum Exposure Limit
has legal status
must not be exceeded
reduce exposure to as
far below the MEL as
concentration at which
no evidence of harm
represents good practice
if exceeded, take steps to
reduce down to OES
OES represents adequate
Two types of occupational exposure
* The key difference between this two types of limit is that an OES is set at a
level at which there is no indication of risk to health
Long term limits
conc. x exposure time
averaged over 8 hours
designed to control
Short term limits
conc. x exposure time
averaged over 15 mins
designed to control acute
OCCUPATIONAL EXPOSURE LIMITS-DURATION
Toxic effects may depend upon exposure duration:
For chemicals having long-term (chronic effects)
-The total dose is the important factor, regardless of
duration (what are the health problems at different
For chemicals having short-term (acute) effects
-Shorter exposure durations must be evaluated
Other routes of exposure
Biological Exposure Indices (BEI)
- BEI limits are established for chemicals having with significant
skin or ingestion exposures
- Exposure are determined using biological specimens
i) Blood, urine, exhaled air
ii) Also used to verify the efficacy of workplace controls
- BEI limits are intended to correspond to other exposure limits
i) Measurements below the BEI show exposures are below
the applicable OEL
Workplace monitoring is carried out for a number of reasons, they are:
Assessing possible health risks resulting from work activities
Assessing the need for and the effectiveness of exposure control measures
Determining compliance with permissible exposure levels of toxic substances
Assessing the effect of changes in processes, materials or controls
Identifying hazardous areas or work tasks that give rise to the most exposure
Investigating complaints concerning alleged health effects
Reassuring employees who may be exposed to toxic airborne contaminants
*Under the Factories Act Section 59(6), regular workplace monitoring is required in any
factory in which toxic chemicals are used or given off.
Monitoring or sampling methods
The method of sampling will depend on the chemical being monitored.
The common air sampling methods are:
a) Sample bag method
- used to collect gases and vapors when the concentration is above the
- these bag are made of inert plastic film.
- air is pumped into the bag and analyzed directly from the bag by
detector tubes, gas chromatography or other instruments.
b) Sorbent tube method
- used for sampling of many gases and hydrocarbon vapors.
- the tube contains a bed of adsorbent such as charcoal or silica gel.
- when air is pulled through the tube, airborne chemicals are trapped by the
-After sampling, the sorbent is removed and the trapped chemicals are
extracted, identified and quantified using gas chromatography or other
c) Impinger method
- used to collect certain inorganic chemicals and some organic chemicals.
- a known volume of air is bubbled through the impinger which contains a
- the liquid will physically dissolve or chemically react with the chemical of
- the liquid is then analyzed by colorimetric, volumetric or other analytical
methods to determine the airborne contaminant concentration.
d) Badge method
- many gases and hydrocarbon vapors can be sampled passively without a
pump, using gas monitoring badges.
- badges are available with a variety of collection media including solid
adsorbent and reagent-filled tubes.
- the air sample comes into contact with the adsorbent by diffusion.
- analysis methods vary with the badge type or chemical sampled and
include color change and gas chromatography.
e) Filter method
- used to collect particulates matters such as dusts, fumes and mists.
- air is pulled through a filter of a specific type and pore size.
- the collected contaminants can be analyzed by gravimetric, microscopic or
atomic absorption technique.
f) Direct reading instruments
- such as detector tube, electrochemical sensors and solid state gas
detector, photo ionizers and infrared analyzer.
- types of direct reading instruments available for measuring gases, vapours
and particulates in air using different principles.
- most direct reading instruments allow for continuous monitoring of the
contaminant level, some have data logging features and alarm settings to
warn users of hazardous conditions.
Selection of measurement techniques/equipment
A number of factors need to be considered prior to selecting an air monitoring
technique / equipment for any particular application are:
Specificity – ability to detect one compound in presence of other contaminants
Accuracy – closeness of result to actual concentration present
Sensitivity – amount of substance that must be present to give a response
Calibration – verify that an instrument is performing acceptably at the
concentration of interest
Interference – reaction of other substances other than the compound of interest
Warning alarm – signals to alert personnel that higher than acceptable average
concentration are present
Data logging features – ability to store monitoring data for time-weighted
average concentration determination
Cost – expense associated with purchase of equipment or supplies
Intrinsic safe – characteristic of equipment required so that it can be used in
Location of sampling
- depends on the objective of sampling or the type of information required
- to maximize the effectiveness of monitoring for assessing exposure
Duration and volume of sampling
- total volume of sampled depends on duration of sampling
- frequency of monitoring depends on the exposure level
What to sample
- type of chemicals to sample will depend on basically two factors:
i) The risk to the workers- depending on chemical are likely to be liberated
into workplace atmosphere
ii) The toxic effects of the chemicals
Permissible exposure levels (PEL)
Assessing risks of exposure to contaminants in working environment, the
result of concentration measurements are compare with their PELs. Two
types of PELs are specified in the Factories (Permissible Exposure Levels of
Toxic Substances) Order:
PEL (Long Term) is the maximum time-weighted average (TWA)
concentration of a toxic substance to which persons may be exposed over
8-hour workday or a 40-hour workweek
PEL (Short Term) is the maximum TWA concentration to which persons
may be exposed over a period of 15 minutes during the workday.
TYPES OF HAZARDOUS CHEMICALS
PRESENT IN LABORATORIES
Hazardous chemicals present physical or health threats to
workers in clinical, industrial and academic laboratories such
The potential that a chemical can cause harmful health effects
depends on two factors:
i) The toxicity of the chemical
- the toxicity of a chemical is an inherent property. However,
a chemical will produce injury or disease only if a worker is
actually exposed to it.
i) The degree of exposure
- the degree of exposure of workers to a chemical will
depend on how it is used and the availability and
effectiveness of the control measures in the workplace.
ROUTES OF ENTRY INTO THE BODY
A chemical may enter into the body through three routes:
- the main route of entry of chemicals into the body.
- excessive exposure may cause direct irritation or local damage to the
respiratory system or injury to tissues within the body.
ii) Skin absorption
- direct contact of the skin with certain chemical may result in primary
irritation or a sensitization reaction similar to an allergic type of response.
- some can penetrate through skin and enter the bloodstream .
- may occur as a result of poor personal hygiene (eating with
- ingested materials may be absorbed into the blood from the intestine.
TOXIC EFFECTS OF CHEMICALS
The effects of exposure to chemicals may be classified in the following ways:
Acute effect- a short-term exposure to usually very high concentration of toxic
chemicals resulting in immediate illness, irritation and even death.
Chronic effect- prolonged or repeated exposure to low concentrations of
noxious substances resulting in certain diseases which may take some time to
Reversible (temporary) effect- an effect that disappears if exposure to the
Irreversible (permanent) effect- an effect that has a lasting, damaging effect
on the body, even if exposure to the chemical ceases.
Local effect- the chemical causes harm at the point of contact or entry.
Systemic effect- the chemical enters the body, is absorbed and transported to
the various organs of the body where harm is effected.
Where the risk of exposure to chemicals is found not acceptable, suitable
control measures must be implemented to minimize the exposure so as to
safeguard the safety and health of the workers.
Point of Control Control measure
At the source Substituting with a less toxic/harmful substance
Changing to a less hazardous process
Installing effective local exhaust ventilation
Along the path Applying dilution ventilation
Increasing the distance between the source and receiver
Practicing good housekeeping
At the receiver Rotation of workers
Training and education of workers
Wearing suitable personal protective equipment
• Changing of processes
• Isolation / Segregation
• Local exhaust ventilation
• Personal protective equipment
• Administrative measures
• Education and training
Some examples of material substitution and their applications are listed in
the following table:
PREVENTING EXPOSURE TO HAZARDOUS
CHEMICALS IN LABORATORIES
Employee information and training
Medical examinations and consultation
Methods of control and personal protective
Safeguards for particularly hazardous substances
What is PPE………?
Personal Protective Equipment (PPE)
PPE means the equipment that is worn to
limit exposure to potentially harmful
substances or conditions.
DEFINITIONS OF PERSONAL PROTECTIVE
Equipment (devicesor clothing) worn to help isolate a worker from
direct exposure to hazardous material / condition / environment
Clothing, equipment and or substance which, when worn or used by
people as a barrier between themselves and the hazard correctly, it may
protect part or all of the body from foreseeable risks of injury or disease at
work or in a workplace
Note: The success of this control is dependent on the protective equipment being chosen correctly,
as well as fitted correctly and worn at all times when required
PRINCIPLES OF PPE PROTECTION
“Prevent contact between
the hazards and the internal
or external parts of the
body to be protected”.
PPE - INTRODUCTION
The significant of PPE
To protect an employee against
hazards including impact, heat or
cold, harmful chemicals, dust and
Mr safety…the figure is too blur…
I can understand it!
Later, I will explain one by one….
Now I want you to Know……
PPE can protect you from head to Toe!
PPE - TYPES
May causes for head injuries if:-
Objects falling from above such as tools.
Bumping head against objects such as pipe or beam.
Direct contact with exposed electrical wiring or components
May causes for eye injuries if:-
Dust and other flying particles such as metal shavings or sawdust.
Corrosive gasses, vapors and liquids.
Molten metal that may splash.
Intense light from welding and lasers.
May causes for body injuries if:
Impact from radiation, hazardious chemical, etc.
Types of control – Last Resort Approach
Other methods not feasible or practicable.
Its use cannot be substituted by any other means.
i. Emergency situation or rescue work.
ii. Close or direct contact is necessary to carry out work.
iii. During cleaning or maintenance operations.
As a back-up or complement.
Correct usage of PPE
Suitability (Fitting, size)
Compatibility of PPE
Ergonomic and other factors
As a final line of defense
“ PPE should not be the first option of control”
May not provide the degree of protection obtained
during laboratory testing
May not be comfortable
May create a new hazard in itself
Protection offered is difficult to measure
Effectiveness often depends on `good fit’ with
If PPE is used as the first option without
reducing hazard at source:
Risk to workers if PPE fails and failure not detected.
Cause employees to believe they are "safe“ and may take
Result in worse consequences if people fail or forget to wear
Will shift the responsibility for safe working condition from
the employer to the employee.
2 Main reasons why employees are required
to be provided with and to use PPE on a
Hazard and risk control
OCCUPATIONAL SAFETY AND HEALTH ACT, 1994(Act 139)
Part IV –General duties of employee & self-employed personSection 15 (1) –it
shall be the duty of employer & every self-employed person to ensure, so
far as practicable, the safety, health & welfare at work of all his employees
OCCUPATIONAL SAFETY AND HEALTH ACT, 1994(Act 139)Part VI –General
duties of employees24. (1) It shall be the duty of every employee while at
work-(c) to wear or use at all times any protective equipment or clothing
provided by the employer for the purpose of preventing risks to his safety
and health; and
OCCUPATIONAL SAFETY AND HEALTH ACT, 1994(Act 139)
Occupational Safety and Health (Use and Standard of Exposure of
Chemicals Hazardous to Health) Regulations 2000 or (USECHH 2000).
TYPES OF PPE
Classification of personal protective equipment
a. Based on protection of body parts/system
-e.g: head, eye and face, hearing
b. Based on type of hazards
- Protection against hazards -chemical, biological,
heat & cold
- Protection against accidents - falls (safety belt);
splash protection (goggles)
Classification of PPE
PPE SELECTION CRITERIA
Selection of PPE is dependent on: i. the hazard identification,
ii. risk assessment, and
iii. control measures implemented
PPE is used to:
i. complement/combination of other control measure
PPE selected must be carried out under a PPE program
PPE must be certified products to ensure acceptable level of
protection from hazards
Limitations of PPE must be identified and adhered to
THE ELEMENTS OF PPE PROGRAM
Training on PPE
Hazard recognition in the work environment
What control measures can be taken
The type of PPE suitable for use
The limitations of PPE
Demonstration of correct use
Practicing using the PPE
Cleaning, storing and maintaining PPE
Use of PPE in dealing with emergencies
May causes for hear injuries if:-
Too expose with noise enviroment.
May causes for foot injuries if:-
Hot or wet surface.
Sharp object such as nails that might be pierce ordinary shoes.
May causes for hand injuries if:-
Punctures, cutting activities, etc
PPE-General Control Measures
At early stage, the identification to assess the workplace to
determine if hazards are present, or are likely to be present, which
necessitate the use of PPE.
This determination need to define because to avoid any wastage.
Cont…PPE-General Control Measures
After selecting PPE, providing the training to the employees who are
required to used it. THEN, PLEASE MAKE SURE what kind of
training that might help them.
…..Why it necessary to our work activities….
….How it will protect us…..
….What are the limitations….
…How to clean and disinfect…
…What is its useful life & how is it disposed….
Implementation during work progress
During the construction daily work, employee need to wear suitable PPE
and have to properly maintained and store it after used.
Cont…PPE-General Control Measures
PPE - SUMMARY
Before selecting appropriate PPE, a careful hazard
assessment should be performed to ensure that the PPE
selected will protect against all relevant hazards.
When worn properly, PPE effectively
reduces risk of injury or death due to
exposure to workplace hazards.
Good implementations of PPE
give a good effect to
construction site safety…..
Eye, face, head, foot, hand and
Eye or face protection must be worn when exposed to hazards from flying
particles, liquid chemicals,dusts, fumes or vapors.
Note that specialized eye protection is required for protection against hazards such
as laser beams and welding
EYE AND FACE PROTECTION
Safety glasses Safety goggles Full-face shields
Hard hats are made of rigid, impact-resistant, non-flammable materials
such as fiberglass and thermoplastics.
Protective helmets designed to reduce electrical shock hazard should be
worn if you are working near exposed electrical conductors.
Thermal liners may be required if you work in extremely cold
To keep your protective headwear in top condition, check it before and
after each use to make sure there are no cracks, signs of wear or
Ensure that the straps are secure and working properly and that the hard
hat fits your head securely.
Always wear gloves that are made of material that is resistant to the
hazards in your workplace.
Before using gloves inspect for holes, tears signs of wear or other defects
and replace if necessary.
You should also replace gloves periodically, depending on the frequency of
use and in accordance with manufacturer’s recommendations.
After use, be sure to remove gloves before handling objects such as
doorknobs, telephones, etc.
Disposable glove Fabric glove Laminate glove
If you need respiratory protection to prevent overexposure to
inhalation hazards you need to:
Select an appropriate respirator based on the specific chemical(s) you may
be exposed to and the conditions under which that exposure occurs.
Have a medical evaluation to ensure that you are capable of wearing
respiratory protection safely.
Attend training in the use, maintenance and limitations of the particular
respirator that you will be using.
Have a fit test to ensure that the respirator fits properly.
The purpose of chemical protective
clothing and equipment is to shield or
isolate individuals from the chemical,
physical and biological hazards that may
be encountered during hazardous
During chemical operations, it is not
always apparent when exposure occurs.
Many chemicals pose invisible hazards
and offer no warning properties
PROTECTIVE CLOTHING APPLICATIONS
Protective clothing must be worn whenever the wearer faces potential
hazards arising from chemical exposure, such as:
Chemical manufacturing and
Hazardous waste site cleanup
Asbestos removal and other
Agricultural application of pesticides
“Within each application, there are several operations which require chemical
protective clothing”. . .
Rescue: entering a hazardous materials area for the purpose of removing
an exposure victim
(special consideration on selected protective clothing may affect the
ability of the wearer to carry out the rescue )
Spill mitigation: entering a hazardous material area to prevent a potential
spill or to reduce the hazards from existing spill
(protective clothing must accommodate the required tasks without
sacrificing adequate protection)
Decontamination: applying decontamination procedures to personnel or
equipment leaving the site
(a lower level of protective clothing is used by personnel involved in
THE CLOTHING ENSEMBLE
Checklist of components that may form the chemical protective ensemble:
Protective clothing (suit, coveralls, hoods, gloves, boots)
Respiratory equipment (SCBA, combination SCBA/SAR, air purifying
Cooling system (ice vest, air circulation, water circulation)
Outer protection (overgloves, overboots, flashcover).
Factors that affect the selection of ensemble components include:
How each item accommodates the integration of other ensemble
components. Some ensemble components may be incompatible due to
how they are worn (e.g., some SCBA's may not fit within a particular
chemical protective suit or allow acceptable mobility when worn).
The ease of interfacing ensemble components without sacrificing required
performance (e.g. a poorly fitting over glove that greatly reduces wearer
Limiting the number of equipment items to reduce donning time and
complexity (e.g. some communications devices are built into SCBA's which
as a unit are NIOSH certified).
CLASSIFICATION OF PROTECTIVE CLOTHING
Personal protective clothing includes the following:
Fully encapsulating suits (protects against splashes, dust, gases, vapors)
Non-encapsulating suits (protects against splashes, dust and other
materials but not against gases and vapors)
Gloves, boots, and hoods (protects against heat, hot water some particles)
Firefighter's protective clothing
Proximity garment, or approach clothing (protects against splashes, dust,
gases and vapors)
Blast or fragmentation suits (provides protection against very small
Radiation-protective suits (protects against alpha and beta particles but
not against gamma radiation)
Heat stress - full body chemical protective clothing puts the wearer at
considerable risk of developing heat stress. This can result in health effects
ranging from transient heat fatigue to serious illness or death.
Heart rate - Count the radial pulse during a 30-second period as early as
possible in any rest period. If the heart rate exceeds 110 beats per minute at
the beginning of the rest period, the next work cycle should be shortened
Oral temperature - Do not permit an end user to wear protective clothing and
engage in work when his or her oral temperature exceeds 100.6°F (38.1°C).
Body water loss- The body water loss should not exceed 1.5% of the total
body weight loss from a response.
- explanation for each part in a group-
submit report during class