Industrial Hygiene Fundamentals

Industrial Hygiene Fundamentals

• Industrial hygiene is the science and art of anticipating, recognizing, evaluating, and controlling environmental factors or stresses in the workplace

Scope of Industrial Hygiene

• The field addresses environmental factors and stresses that can cause sickness, impaired health, discomfort among workers, or among community citizens

Industrial Hygiene vs. Safety

• Safety focuses on preventing accidents and incidents
• Industrial Hygiene (IH) focuses on the prevention of occupational illnesses

Basics of Industrial Hygiene

• IH involves a continuous cycle of:
  • Identification of risks
  • Evaluation through exposure assessment, measurement strategies, monitoring, and reporting.
  • Control via respecting the hierarchy of controls

Types of Hazards

• Chemical agents include gases, vapors, and dust (API & IP)
• Physical agents include noise, vibration, IR, NIR, and climate factors
• Ergonomics address repetition, posture, and workforce-related issues
• Biological agents include biohazards, fungi, allergens, and toxins

Chemical Hazards Examples

• Dusts
• Mists
• Fumes
• Vapors
• Gases

Physical Hazards Examples

• Noise
• Vibrations
• Ionizing Radiation (Alpha, Beta, Gamma)
• Non-ionizing Radiation (UV light, visible light, infrared, radio waves, microwaves)

Biological Hazards Examples

• Viruses
• Fungi or Molds
• Bacteria
• Plants
• Insects
• Animals

Occupational Diseases

• Occupational diseases can result from exposure to chemical, physical, or biological hazards
• Reactions can be acute or chronic (gradual or delayed)

Occupational Health Hazards: Reaction Types

• Immediate or acute reactions: Shortness of breath or nausea from a chemical spill, usually without permanent reactions
• Gradual reactions: Asthma or dermatitis from prolonged exposure
• Delayed reactions: Lung cancer or hearing loss from long-term exposure

Examples of Occupational Diseases

• Acute poisoning
• Occupational cancer
• Chronic poison
• Interstitial lung disease
• Skin disease
• Hearing loss
• Muscular disorders
• Lower-back morbidity and trauma of the spine

Hazardous substances

• Hazardous substances can have harmful effects on health
• Examples include:
  • Chemicals such as organic solvents and acids
  • Dust such as metal and wood particles
  • Fumes from welding and soldering
  • Fibers such as asbestos

Routes of Entry for Hazardous Substances

• Inhalation
• Dermal (skin) absorption
• Ingestion

Type of Health Effects

• Acute - Immediate reaction
• Chronic - Develop over years

Toxicity

• All substances are toxic; the dose differentiates a poison from a medicine -- Paracelsus (1493-1541)
• The intrinsic possibility of a chemical substance to cause irreversible effects into a biological system

Describing Hazards & OEL

• The Occupational Exposure Limit (OEL) indicates how much of a substance a worker can breathe without harm

Occupational Exposure Limits (OELs)

• Represents the airborne concentration nearly all workers can be repeatedly exposed to without adverse health effects

Threshold Limit Value (TLV)

• The TLV is defined by ACGIH (American Conference of Governmental Industrial Hygienists)

OEL Reference Periods

• 8-hour reference period: Expressed as TLV-TWA (Time-Weighted Average)
• 15-minute reference period: Called Short Term Exposure Limit (STEL), not to be exceeded even if the 8-hour TWA is within TLV-TWA; Excursions above the TLV-TWA but below the TLV-STEL should not more than 4 times a day, with 60 minutes between
• Ceiling (TLV-C): Concentration not to be exceeded during any part of the working exposure

Authority for common hazardous substances

• Your national health and safety authority
• ACGIH, which is also know as Threshold Limit Value, or TLV

Setting OEL's

• The OEL set by your health and safety authority and ACGIH might be different so it is crucial to use to LOWER OEL

Setting an OEL – what to consider

• Animal studies, Pharmaceutical trials – These indicate the lowest active dose, or the dose where there is no observed adverse effect

Factors Influencing the Effect on the Body

• Breathing rate
• Body weight
• Chemical retention time
• Absorption rate
• Hazardous substances formed

OEL Calculation

• OEL = (LAD x BW) / (V x T x SF x α)
  • LAD = Lowest Active Dose
  • BW = Body Weight (50 kg)
  • V = Volume Inhaled Air (10 m^3)
  • T = Time to Reach Steady State in Plasma
  • SF = Safety Factor
  • α = Absorption (Assumed = 100%)

Notes given with OEL's

• Carcinogenic, mutagenic, or reproductive toxin
• Substances that penetrate intact skin
• Skin or respiratory sensitization could occur where intense response occurs to low concentrations after a person has become sensitised
• BEI is recommended for the substance

Acceptable Surface Limits

• A surface limit is sometimes set and it is helpful:
  • If there might be significant exposure through the skin
  • If potent substances might be re-suspended and inhaled to indicate contamination of surfaces
• It is the acceptable mass on a specified surface area, about 10 x 10 cm
• Often set to 10x the OEL
• It is less frequently used as OEL
• It is not typically set by ACGIH

Using OEL and ASL Values

• Compare exposure monitoring results with the OEL
• When using respiratory protection, compare the exposure inside the mask with the OEL to gauge effectiveness
• Compare measured surface concentrations with the ASL

Cumulative Effect

• Exposure to multiple substances requires assessing cumulative effects
• Σ (Cn / GWn) < 1, where Cn is the measured concentration and GWn is the OEL of each substance

Odor as Indicator

• Odor is not a reliable detection system
• Some substances have no odor (CO, nitrogen)
• With some substances, the odor level is above the OEL
• Odor habituation can occur

Risk Assessment

• Risk management includes.
  • Hazard Identification
  • Dose-Response Relationship
  • Exposure Assessment
  • Risk Characterisation

Risk Assessment Steps

• Hazard identification, dose-response assessment, exposure assessment, and risk characterization

Hazardous Substances Identification: Processes

• CHA/PHA/PHR (Process Hazard Analysis / Review) is a theoretical exposure evaluation

Hazardous Substances Identification: Raw Materials

• Examining chemical & toxicological properties and user information

Evaluation of Risks

• Workplace monitoring evaluates exposure, it is stationary, personal, portable, fixed, short term / 8 hours
• Bio monitoring evaluates effects on individual employee through:
  • Blood and urine tests
  • Long function tests
  • Clinical evaluation

Hazardous substances Evaluation

• Different measuring principles on gases and vapors can done through use of Long term leak detection, Bio monitoring, and Stationary monitoring

Installations: Control Measures

• Include Engineering controls, Administrative controls, and Personal protective equipment.
• Engineering controls: Includes Closed transfer, Isolators, Compartments, and Local & overall ventilation
• Administrative controls: Procedures, and Safe behaviour analyses
• Personal protective equipment

Engineering Controls

• Includes High integrity transfer, Isolator technology, Closed Transfer, Direct Laminar Flow, Laminar Flow and Local ventilation

Hierarchy of Controls

• Elimination
• Substitution
• Local / General Ventilation
• Contained Installations
• Administrative Controls
• Personal Protective Equipment

Elimination - Control :

• Elimination control measures is to removing asbestos

Substitution - Control

• Substitution control measures involves choloroform, benzene, and 1,2-DCE

Encapsulation - Control

• Encapsulation control measures involves isolators

Overall - Control

• Overall and local ventilation controls are applied to reduce exposure

Procedures - Control

• Procedures and instructions includes work instructions

Hazard Substances contorl

• Hazardous substances can be controlled through Elimination, Substitution, Encapsulation, Overall & local ventilation, Procedures & instructions and Personal protective equipment

Biological Hazards

• The 'biological agents' are micro-organisms, including those which have been genetically modified, cell cultures and human endoparasites, which may be able to provoke any infection, allergy or toxicity.
• Biological hazards: Bacteria, Viruses, fungi, plants, insects, animals

Exposure to Biological Hazards

• Activities where there is a possible exposure to biological hazards include: food production, activities involving animals and/or products of animal origin, health care, refuse disposal plants, and sewage purification installations.

Biological Agents: Risk Groups

• Risk groups of biological agents are classified by their level of risk of infection levels.
  • Group 1: Unlikely to cause human disease.
  • Group 2: Can cause human disease and might be a hazard to workers; unlikely to spread to the community; and there is usually effective prophylaxis or treatment available.
  • Group 3: It may present a risk of spreading to the community, but there is usually effective prophylaxis or treatment available
  • Group 4: Causes severe human disease and is a serious hazard to workers; it may present a high risk of spreading to the community; there is usually no effective prophylaxis or treatment available.

Risk Management with Biological agents :

• It is crucial to prevent exposire harmful biological agents with other safer agent.
• Risk protection measures are needed
  • These protection measures should respect : construction of the workplace, registrations of exposures, notification of the Government, training programs and collective protection

Risk Reduction Procedures of a Biologocial Hazard

• H&S of the workers must be kept in mind
  • Work processes and engineering controls to avoid or minimize the release of biological agents;

Hygiene and Individual Protection

• Crucial for preventing biological contamination like: -Protective equipment properly stored, checked cleaned and replaced if needed -Work clothes and protective equipment and must be decontaminated, removed and kept separately

Physical Hazards: Noise

• Noise is defined as unwanted sound
• Noise is measured in decibels (dB)
• A-weighting: Used to measure average noise levels
• C-weighting: Used to measure peak, impact or explosive noises
• Every 3 dB doubles the noise.

Noise: Physical Hazards

• To evaluate the physical parameter of the noise hazard it is defined as risk noise exposure level (LEX,8h) (dB(A) re, the time-weighted average of noise exposure levels, for a nominal 8-hour working day

Noise: Effects

• Hearing impairment and hearing disorders.
• Noise and pregnant workers
• Risk prevention means assessment + consultation training and information
  • Prevention of exposure and health surveillance

Noise: Risk Assessment-

• Effects on the noise levels are a concern, also effects caused by warning signals

Noise: Risk Reduction

• Risk reducation should include use of PPE, and reduction by technical means
  • Techincal means are shields, enclosures of the noise

Noise: Organizational & Administrative Control

• Work methods that produce less noise, and should be an evaluation factor in the procurement factors and procurement policy of noise levels

Hearing Protection

• Protectors should be selected so that technical noise control is ineffective, and make sure that the exposure limit values are not exceeded;

Types of Hearing Protection Devices

• Earplugs: Inserts a noise blocking seal.
• Earmuffs: Enclose the outer ear and seal.
• Earmuffs With incorporated active noise cancellation

Noise: Instructions and Training

• There should be instructions and training to the workers on potential hazard, what is being done to protect them, how to use ppe, and safe work practices

Physical Hazards: Vibrations

• Vibration is mechanical oscillation about a reference position.
• It is is an everyday phenomenon.
• Both hand-arm and whole-body vibrations exposures are concerns.

Vibrations: Hand-Arm

• Transmitted to the human hand-arm system, entails risks to the health and safety of workers,
• Assessment is based on the measurement of average daily value normalized and is measured around the orthogonal axes
• hand-arm: OEL- 5m/s, Action- 2,5m/s

Reduction: Vibration

• Implementation of new techniques with less exposure and equipment with auxiliary support is recommended

Radiation: Types

• There are two types of Radiation: Ionizing radiation (high energy), and Non-ionizing radiation (low energy), or microwaves

Ionizing Radiation:

• There are 3 types of ionizing radiation; alpha, beta & gamma radiation
• Radiation sickness occurs after exposure to a very high dose of radiation, Exposure to a radiation can lead to tumors and cancer

Non-Ionizing Radiation:

• There are different types and include: -UV: Welding arcs, lasers or Visible light TL-tubes -Infrared heaters, and Microwaves sealers or heaters

Prolonged Exposure to low levels - Radiation

• Prolonged exposure to low levels could cause health damage
• Prolong exposure can be inflammatory