Industrial Safety and Hazard Management
Key Takeaways
- Industrial hygiene identifies, evaluates, and controls workplace hazards to protect worker health.
- OSHA (Occupational Safety and Health Administration) sets and enforces workplace safety standards.
- Permissible Exposure Limits (PELs) and Threshold Limit Values (TLVs) set maximum safe exposure levels.
- Safety Data Sheets (SDS, formerly MSDS) provide comprehensive hazard information for every chemical in the workplace.
- The hierarchy of controls: elimination > substitution > engineering controls > administrative controls > PPE.
- Confined space entry requires atmospheric testing, ventilation, attendant, and rescue procedures.
Industrial Safety and Hazard Management
FE Exam Weight: Safety, Health, and Environment accounts for 6-9 questions (~7% of the exam). This section tests your knowledge of workplace safety regulations and hazard control.
Industrial Hygiene
Industrial hygiene is the science of anticipating, recognizing, evaluating, and controlling workplace environmental factors that may cause illness, impaired health, or significant discomfort to workers.
Types of Workplace Hazards
| Category | Examples |
|---|---|
| Chemical | Toxic gases, fumes, vapors, dusts, solvents |
| Physical | Noise, vibration, radiation, temperature extremes |
| Biological | Bacteria, viruses, molds, bloodborne pathogens |
| Ergonomic | Repetitive motion, awkward postures, heavy lifting |
| Psychosocial | Stress, workplace violence, fatigue |
Exposure Limits
| Term | Acronym | Definition |
|---|---|---|
| Permissible Exposure Limit | PEL | OSHA legal limit — 8-hour time-weighted average (TWA) |
| Threshold Limit Value | TLV | ACGIH recommended limit — 8-hour TWA |
| Short-Term Exposure Limit | STEL | Maximum 15-minute exposure |
| Ceiling | C | Never-to-be-exceeded concentration |
| Immediately Dangerous to Life/Health | IDLH | Maximum concentration for 30-minute escape |
Time-Weighted Average (TWA)
where Ci = concentration during period i, ti = duration of period i.
Example: A worker is exposed to 50 ppm for 3 hours, 80 ppm for 2 hours, and 20 ppm for 3 hours: TWA = (50×3 + 80×2 + 20×3)/8 = (150+160+60)/8 = 370/8 = 46.25 ppm
Hierarchy of Controls
From most effective to least effective:
- Elimination — Remove the hazard entirely (redesign the process)
- Substitution — Replace hazardous material/process with less hazardous one
- Engineering Controls — Isolate workers from the hazard (ventilation, guards, enclosures)
- Administrative Controls — Change work practices (training, job rotation, scheduling)
- PPE (Personal Protective Equipment) — Last resort (respirators, gloves, goggles, hard hats)
Exam Key: PPE is always the LAST resort, not the first. Engineering controls are preferred over administrative controls.
Safety Data Sheets (SDS)
Formerly called Material Safety Data Sheets (MSDS). Required for ALL hazardous chemicals in the workplace.
16 SDS Sections (GHS Format)
- Identification
- Hazard identification
- Composition/ingredients
- First aid measures
- Firefighting measures
- Accidental release measures
- Handling and storage
- Exposure controls/PPE
- Physical/chemical properties
- Stability and reactivity
- Toxicological information
- Ecological information
- Disposal considerations
- Transport information
- Regulatory information
- Other information
Gas Detection and Monitoring
| Gas | Common Sources | Hazard |
|---|---|---|
| O₂ | Atmosphere | < 19.5% = deficient, > 23.5% = enriched (fire risk) |
| CO | Combustion | Toxic — replaces O₂ in hemoglobin |
| CO₂ | Respiration, combustion | Displaces O₂; > 5,000 ppm is TLV |
| H₂S | Decaying organic matter, petroleum | Toxic; deadens sense of smell at high conc. |
| CH₄ | Natural gas, anaerobic decomposition | Explosive at 5-15% in air (LEL-UEL) |
| Radon | Soil, rock, groundwater | Radioactive; lung cancer risk |
Explosive/Flammable Limits
- LEL (Lower Explosive Limit): Minimum concentration for ignition
- UEL (Upper Explosive Limit): Maximum concentration for ignition
- Between LEL and UEL = explosive range
Confined Space Entry
A confined space: (1) large enough to enter, (2) limited entry/exit, (3) not designed for continuous occupancy.
Required Precautions
- Atmospheric testing before and during entry (O₂, combustibles, toxic gases)
- Ventilation — continuous mechanical ventilation
- Attendant — stationed outside at all times
- Communication — between entrant and attendant
- Rescue plan — retrieval system, trained rescue team
- Entry permit — documenting conditions and controls
- Lockout/Tagout — all energy sources isolated
Electrical Safety
| Voltage | Hazard Level |
|---|---|
| < 50 V | Generally safe |
| 50-600 V | Potentially lethal (most common electrocutions) |
| > 600 V | High voltage — arc flash risk |
Lockout/Tagout (LOTO): De-energize equipment and lock the energy isolation device before maintenance. Tag indicates who locked it out and why.
Personal Protective Equipment (PPE)
| Hazard | PPE |
|---|---|
| Head impact | Hard hat (ANSI Z89.1) |
| Eye/face | Safety glasses, goggles, face shields |
| Hearing | Earplugs, earmuffs (when > 85 dBA) |
| Respiratory | N95, half-face, full-face, SCBA |
| Hands | Chemical gloves (material depends on chemical) |
| Feet | Steel-toe boots |
| Fall | Harness and lanyard (> 6 ft height) |
According to the hierarchy of controls, which control method is MOST effective?
A worker is exposed to a chemical at 40 ppm for 4 hours and 80 ppm for 4 hours. What is the 8-hour TWA?
What is the minimum oxygen concentration considered safe for a normal work atmosphere?
Before entering a confined space, what must be done FIRST?
What does the GHS hazard communication system require for every hazardous chemical in the workplace?
A workplace has noise levels at 95 dBA. At what level must hearing protection be provided by the employer?