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Class notes topic 3

  1. 1. TOPIC 3 : CHEMICAL HAZARD ASSESSMENT AND PROTECTION Outline of topic 3: EXPOSURE LIMITS 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
  2. 2. Introduction WHAT IS YOUR UNDERSTANDING? • Who are you ? • What is your role? • We have any ISSUES for these? • Are you important for this ISSUES…….?
  3. 3. INTRODUCTION 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. EXAMPLES: Acetronitrile, Acids,Asbestos,Beryllium,Cadmium,Cyanide compounds, Hydrogen Chloride, Hydrogen Fluoride,Lead,Lithium compounds,Mercury,Methylene Chloride, Nickel,PCBs,Sodium,Uranium.
  4. 4. CONTINUE
  5. 5. 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 accepted standards. EXPOSURE LIMITS
  6. 6. EXPOSURE 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 disposal.
  7. 7. OCCUPATIONAL EXPOSURE
  8. 8. • 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 MEASUREMENT
  9. 9. • harmful characteristics of the substance, energy or condition involved • concentration, intensity or level of the exposure to the harmful agent • time duration of the exposure EVALUATION
  10. 10. • 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 to damage) CONTROL
  11. 11. • 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 air) • 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
  12. 12. Maximum Exposure Limit (MEL)  maximum permissible concentration  has legal status  must not be exceeded  reduce exposure to as far below the MEL as possible Occupational Exposure Standard (OES)  concentration at which no evidence of harm  represents good practice  if exceeded, take steps to reduce down to OES  OES represents adequate control Two types of occupational exposure limits * 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 confirmation awareness
  13. 13. Long term limits  time-weighted average concentration  conc. x exposure time averaged over 8 hours  designed to control chronic effects Short term limits  time-weighted average concentration  conc. x exposure time averaged over 15 mins  designed to control acute effects
  14. 14. 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 exposure)  For chemicals having short-term (acute) effects -Shorter exposure durations must be evaluated
  15. 15. 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
  16. 16. WORK PLACE AND PERSONAL MONITORING
  17. 17. WORKPLACE MONITORING 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.
  18. 18. 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 detection limits. - 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.
  19. 19. 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 adsorbent. -After sampling, the sorbent is removed and the trapped chemicals are extracted, identified and quantified using gas chromatography or other analytical methods.
  20. 20. 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 liquid medium. - the liquid will physically dissolve or chemically react with the chemical of interest. - the liquid is then analyzed by colorimetric, volumetric or other analytical methods to determine the airborne contaminant concentration.
  21. 21. 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.
  22. 22. 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.
  23. 23. 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.
  24. 24. 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 certain area
  25. 25. Sampling strategies  Location of sampling - depends on the objective of sampling or the type of information required  Personal sampling - to maximize the effectiveness of monitoring for assessing exposure hazard  Duration and volume of sampling - total volume of sampled depends on duration of sampling  Frequency - 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
  26. 26. 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.
  27. 27. TYPES OF HAZARDOUS CHEMICALS PRESENT IN LABORATORIES Hazardous chemicals present physical or health threats to workers in clinical, industrial and academic laboratories such as: Carcinogens Toxins Irritants Corrosives Sensitizers Hepatotoxins Nephrotoxins Neurotoxins
  28. 28. TOXIC CHEMICALS 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.
  29. 29. ROUTES OF ENTRY INTO THE BODY A chemical may enter into the body through three routes: i) Inhalation - 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 . iii) Ingestion - may occur as a result of poor personal hygiene (eating with contaminated hands) - ingested materials may be absorbed into the blood from the intestine.
  30. 30. 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 develop.  Reversible (temporary) effect- an effect that disappears if exposure to the chemical ceases.  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.
  31. 31. CONTROL MEASURES 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
  32. 32. Engineering Control • Substitution/Elimination • Changing of processes • Enclosure • Isolation / Segregation • Local exhaust ventilation • Housekeeping • Personal protective equipment • Administrative measures • Education and training
  33. 33. Some examples of material substitution and their applications are listed in the following table:
  34. 34. PREVENTING EXPOSURE TO HAZARDOUS CHEMICALS IN LABORATORIES  Chemical-hygiene plan  Employee information and training  Medical examinations and consultation  Methods of control and personal protective equipment  Safeguards for particularly hazardous substances  Hazard identification  Recordkeeping
  35. 35. PPE- INTRODUCTION What is PPE………? Personal Protective Equipment (PPE) PPE means the equipment that is worn to limit exposure to potentially harmful substances or conditions.
  36. 36. DEFINITIONS OF PERSONAL PROTECTIVE EQUIPMENT (PPE)  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
  37. 37. PRINCIPLES OF PPE PROTECTION “Prevent contact between the hazards and the internal or external parts of the body to be protected”.
  38. 38. PPE - INTRODUCTION The significant of PPE To protect an employee against hazards including impact, heat or cold, harmful chemicals, dust and others. Mr safety…the figure is too blur… I can understand it! Don’t worry…. Later, I will explain one by one…. Now I want you to Know…… PPE can protect you from head to Toe!
  39. 39. PPE - TYPES Hard hat Safety glasses, goggles Gloves Earplugs, earmuffs Safety and shoes boots Face shield Respirators
  40. 40. PPE-Typical Hazards  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: Intense heat. Impact from radiation, hazardious chemical, etc.
  41. 41. 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.  Temporary measure.  As a back-up or complement.
  42. 42. Correct usage of PPE  Suitability (Fitting, size)  Consistent  Compatibility of PPE  Ergonomic and other factors  Maintenance  As a final line of defense
  43. 43. “ PPE should not be the first option of control” Limitation  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 workers
  44. 44. 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 higher risks.  Result in worse consequences if people fail or forget to wear equipment.  Will shift the responsibility for safe working condition from the employer to the employee.
  45. 45. 2 Main reasons why employees are required to be provided with and to use PPE on a certain task; Hazard and risk control Legal requirement
  46. 46. REGULATORY REQUIREMENTS 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).
  47. 47. 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)
  48. 48. Classification of PPE  Head protection  Eye protection  Hearing protection  Foot protection Body protection  Respiratory protection
  49. 49. 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
  50. 50. 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
  51. 51. Cont..PPE-Typical Hazards  May causes for hear injuries if:- Too expose with noise enviroment.  May causes for foot injuries if:-  Slippery surfaces. Hot or wet surface. Sharp object such as nails that might be pierce ordinary shoes.  May causes for hand injuries if:-  Chemical exposers.  Burning activities.  Punctures, cutting activities, etc
  52. 52. 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. WHY?.............................. This determination need to define because to avoid any wastage.
  53. 53. 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….
  54. 54. 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
  55. 55. 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…..
  56. 56. Eye, face, head, foot, hand and respiratory protection
  57. 57. 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
  58. 58. HEAD PROTECTION  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 temperatures.  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 discoloration.  Ensure that the straps are secure and working properly and that the hard hat fits your head securely.
  59. 59. FOOT PROTECTION  Reinforced Safety-Toe Shoes  Reinforced Safety Boots  Neoprene or Nitrile Boots  Electrical Hazard Boots
  60. 60. HAND PROTECTION  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
  61. 61. RESPIRATORY PROTECTION 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.
  62. 62. Chemical protective clothing
  63. 63. INTRODUCTION  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 material operations.  During chemical operations, it is not always apparent when exposure occurs.  Many chemicals pose invisible hazards and offer no warning properties
  64. 64. PROTECTIVE CLOTHING APPLICATIONS Protective clothing must be worn whenever the wearer faces potential hazards arising from chemical exposure, such as:  Emergency response  Chemical manufacturing and process industries  Hazardous waste site cleanup and disposal  Asbestos removal and other particulate operations  Agricultural application of pesticides
  65. 65. “Within each application, there are several operations which require chemical protective clothing”. . . Emergency response  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 decontamination)
  66. 66. 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 respirators)  Cooling system (ice vest, air circulation, water circulation)  Communications device  Head protection  Eye protection  Ear protection  Inner garment  Outer protection (overgloves, overboots, flashcover).
  67. 67. 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 dexterity).  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).
  68. 68. 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 detonations)  Radiation-protective suits (protects against alpha and beta particles but not against gamma radiation)
  69. 69. RISKS  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 by one-third.  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.
  70. 70. DISCUSSION summary - explanation for each part in a group- submit report during class

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